Showing papers in "Journal of Medical Genetics in 1997"

Spectrum of clinical features associated with interstitial chromosome 22q11 deletions: a European collaborative study.

Abstract: We present clinical data on 558 patients with deletions within the DiGeorge syndrome critical region of chromosome 22q11. Twenty-eight percent of the cases where parents had been tested had inherited deletions, with a marked excess of maternally inherited deletions (maternal 61, paternal 18). Eight percent of the patients had died, over half of these within a month of birth and the majority within 6 months. All but one of the deaths were the result of congenital heart disease. Clinically significant immunological problems were very uncommon. Nine percent of patients had cleft palate and 32% had velopharyngeal insufficiency, 60% of patients were hypocalcaemic, 75% of patients had cardiac problems, and 36% of patients who had abdominal ultrasound had a renal abnormality. Sixty-two percent of surviving patients were developmentally normal or had only mild learning problems. The majority of patients were constitutionally small, with 36% of patients below the 3rd centile for either height or weight parameters.

Global prevalence of putative haemochromatosis mutations.

Abstract: Haemochromatosis is a genetic disease associated with progressive iron overload, and is common among populations of northern European origin HLA-H is a recently reported candidate gene for this condition Two mutations have been identified, a substitution of cysteine for tyrosine at amino acid 282 (C282Y, nucleotide 845) and of histidine for aspartate at amino acid 63 (H63D, nucleotide 187) Over 90% of UK haemochromatosis patients are homozygous for the C282Y mutation We have examined 5956 chromosomes (2978 people) for the presence of HLA-H C282Y and H63D by PCR followed by restriction enzyme analysis We have found world wide allele frequencies of 19% for C282Y and 81% for H63D The highest frequencies were 10% for C282Y in 90 Irish chromosomes and 304% for H63D in 56 Basque chromosomes C282Y was most frequent in northern European populations and absent from 1042 African chromosomes, 484 Asian chromosomes, and 644 Australasian chromosomes The distribution of the C282Y mutation coincides with that of populations in which haemochromatosis has been reported and is consistent with the theory of a north European origin for the mutation The H63D polymorphism is more widely distributed and its connection with haemochromatosis remains unclear

Intelligence and psychosocial adjustment in velocardiofacial syndrome: a study of 37 children and adolescents with VCFS.

Abstract: We report data on a group of 37 VCFS patients with specific reference to their intelligence, behaviour, and social competence. Fifty five percent of the children had a borderline to normal IQ. Mental retardation (defined as IQ -2 SD below the mean) was found in 45%. In the majority, the mental retardation was mild (38%) and only two patients had moderate mental retardation. Severe mental retardation seems to be rare in VCFS. The present study shows also that the incidence of mental retardation is much higher in the familial than the de novo group. Intelligence is not correlated with the presence or absence of a heart defect. Significantly higher verbal IQs than performance IQs (probably related to deficits in visuospatial-perceptual functioning) were found. Problems in social-emotional functioning and attention were also found. Further longitudinal studies are necessary to provide an accurate prognosis and appropriate intervention for VCFS children.

Peutz-Jeghers syndrome.

Abstract: Peutz-Jeghers syndrome (PJS, MIM 175,2000) is a disease of autosomal dominant inheritance that is characterised by hamartomatous gastrointestinal polyps and mucocutaneous pigmentation. In addition to problems such as intussusception, PJS predisposes to cancers of several sites. The unusual combination of clinical features makes the identification of the defect underlying PJS particularly interesting. Recently, the PJS gene has been mapped to chromosome 19p13.

Methylenetetrahydrofolate reductase polymorphism and pre-eclampsia.

Abstract: A common missense mutation in the methylenetetrahydrofolate reductase (MTHFR) gene, a C to T substitution at nucleotide 677, is responsible for reduced MTHFR activity and associated with modestly increased plasma homocysteine concentrations. Since underlying maternal vascular disease increases the risk of pre-eclampsia, we had the working hypothesis that pre-eclampsia patients would have an increased T677 allele frequency compared with controls. The MTHFR genotypes were determined in 67 pre-eclampsia patients, 98 normal pregnant women, and 260 healthy adults by the PCR/RFLP method. The T677 allele and the genotype homozygous for the T677 allele were significantly increased in the pre-eclamptic group compared with the controls (p < 0.02 and p < 0.004, respectively). The data indicate that the T677 variant of the MTHFR gene is one of the genetic risk factors for pre-eclampsia.

Wolfram (didmoad) syndrome

Abstract: Wolfram syndrome (MIM 222300) is the association of juvenile onset diabetes mellitus and optic atrophy, also known as DIDMOAD (Diabetes Insipidus, Diabetes Mellitus, Optic Atrophy, and Deafness). Patients present with diabetes mellitus followed by optic atrophy in the first decade, cranial diabetes insipidus and sensorineural deafness in the second decade, dilated renal outflow tracts early in the third decade, and multiple neurological abnormalities early in the fourth decade. Other abnormalities include primary gonadal atrophy. Death occurs prematurely, often from respiratory failure associated with brainstem atrophy. Most patients eventually develop all complications of this progressive, neurodegenerative disorder. The pathogenesis is unknown, but the prevalence is 1 in 770000 in the UK and inheritance is autosomal recessive. A Wolfram gene has recently been mapped to chromosome 4p16.1, but there is evidence for locus heterogeneity, and it is still possible that a minority of patients may harbour a mitochondrial genome deletion. The best available diagnostic criteria are juvenile onset diabetes mellitus and optic atrophy, but there is a wide differential diagnosis which includes other causes of neurodegeneration.

Bardet-Biedl syndrome: a molecular and phenotypic study of 18 families.

Abstract: The autosomal recessive disorder Bardet-Biedl syndrome is characterised by retinal degeneration, polydactyly, obesity, mental retardation, hypogenitalism, renal dysplasia, and short stature. It is heterogeneous with at least four gene loci (BBS1-4) having been mapped to date. We have studied 18 multiply affected families noting the presence of both major and minor manifestations. Using a fluorescently based PCR technique, we genotyped each family member and assigned linkage to one of the four loci. Given this degree of heterogeneity we hoped to find phenotypic differences between linkage categories. We found 44% of families linked to 11q13 (BBS1) and 17% linked to 16q21 (BBS2). Only one family was linked to 15q22 (BBS4) and none to 3p12. We conclude that BBS1 is the major locus among white Bardet-Biedl patients and that BBS3 is extremely rare. Only subtle phenotypic differences were observed, the most striking of which was a finding of taller affected offspring compared with their parents in the BBS1 category. Affected subjects in the BBS2 and 4 groups were significantly shorter than their parents. Twenty eight percent of pedigrees did not show linkage to any known locus, evidence for at least a fifth gene. We conclude that the different genes responsible for Bardet-Biedl syndrome may influence growth characteristics such as height.

Nemaline myopathy: Current concepts

Abstract: *ENMC International Consortium on Nemaline Myopathy: Dr Anthony Akkari, USA; Prof Richard Barohn, USA; Prof Peter Barth, The Netherlands; Dr Alan Beggs, USA; Prof Albert de la Chapelle, Finland; Prof Marianne de Visser, The Netherlands; Prof Victor Dubowitz, UK; Dr Marc Fiszman, France; Prof Hans Goebel, Germany; Prof Susan lannaccone, USA; Dr Bharat Jasani, UK; Dr Siegfried Labeit, Germany; Dr Nigel Laing, Australia; Dr Martin Lammens, Belgium; Dr Carmen Navarro, Spain; Dr Geoffrey Newman, UK; Dr Kathryn North, Australia; Dr Katrina Pelin, Finland; Dr Norma Romero, France; Dr Caroline Sewry, UK; Dr Avril Sloane, Canada; Dr Carina Wallgren-Pettersson, Finland. Definition Nemaline (rod) myopathy, first described in 1963 by Shy et al' and Conen et al,' is assigned to the group of congenital myopathies. These muscle disorders are defined on the basis of structural abnormalities of the muscle fibres, visible after staining of muscle biopsy sections with histochemical methods. The histological definition of nemaline myopathy is based on the presence of threador rod-like bodies, the nemaline (rod) bodies in the muscle fibres of patients. (7Med Genet 1997;34:705-713)

Maternal uniparental disomy 7 in Silver-Russell syndrome.

Abstract: Silver-Russell syndrome (SRS) is characterised by intrauterine and postnatal growth failure accompanied by a variable number of dysmorphic features. It is usually sporadic although a few familial cases have been described. In a prospective study of 33 patients with sporadic SRS, we have studied the parent of origin of chromosome 7 using variable number tandem repeat (VNTR) or microsatellite repeat markers and have identified two patients with maternal uniparental disomy of chromosome 7 (mUPD7). In one family, inconsistent inheritance of paternal alleles of markers on chromosomes other than 7 led to their exclusion from further study. The probands were clinically mild and symmetrical, but showed no gross clinical differences from the 30 patients with chromosome 7 derived from both parents.

Mutation in the mitochondrial 12S rRNA gene in two families from Mongolia with matrilineal aminoglycoside ototoxicity.

Abstract: Irreversible hearing loss is a catastrophic complication of treatment with aminoglycoside antibiotics such as streptomycin, gentamycin, and kanamycin. Many kindreds showing a matrilineal pattern of inheritance of this trait have been described in China where the widespread use of aminoglycoside antibiotics accounts for approximately 25% of profound deafness in some districts. Because of the characteristic inheritance pattern, mitochondrial DNA (mtDNA) mutations were postulated to be the cause of the deafness in these pedigrees. In 1993 it was shown that an A to G substitution at base pair 1555 of the mitochondrial 12S ribosomal RNA gene was the only mutation common to all the families with aminoglycoside ototoxicity. We ascertained three Mongolian pedigrees from the School for the Deaf and Blind in Ulaanbaatar, all of which contained multiple affected subjects with streptomycin induced deafness in a pattern consistent with matrilineal transmission. Amplified mtDNA, obtained from transformed lymphoblastoid cell lines using previously described primers, showed the A to G point mutation in the 12S rRNA gene in two of the three families by restriction analysis as well as direct sequencing. No other example of this substitution was found among 400 control samples from Mongolians with normal hearing. We have thus confirmed the clinical relevance of the 1555 A to G mitochondrial mutation in the 12S rRNA gene by identifying it in affected subjects with familial aminoglycoside ototoxicity in another ethnic group. In countries where aminoglycosides are widely used, genetic counselling and screening of high risk families before the use of these drugs could have a dramatic effect on the incidence of deafness.

The genetics of primary nocturnal enuresis: inheritance and suggestion of a second major gene on chromosome 12q.

Abstract: Primary nocturnal enuresis (PNE), or bedwetting at night, affects approximately 10% of 6 year old children. Genetic components contribute to the pathogenesis and recently one locus was assigned to chromosome 13q. We evaluated the genetic factors and the pattern of inheritance for PNE in 392 families. Dominant transmission was observed in 43% and an apparent recessive mode of inheritance was observed in 9% of the families. Among the 392 probands the ratio of males to females was 3:1 indicating sex linked or sex influenced factors. Linkage to candidate regions was tested in 16 larger families segregating for autosomal dominant PNE. A gene for PNE was excluded from chromosome 13q in 11 families, whereas linkage to the interval D13S263-D13S291 was suggested (Zmax = 2.1) in three families. Further linkage analyses excluded about 1/3 of the genome at a 10 cM resolution except the region around D12S80 on chromosome 12q that showed a positive two point lod score in six of the families (Zmax = 4.2). This locus remains suggestive because the material was not sufficiently large to give evidence for heterogeneity. Our pedigree analysis indicates that major genes are involved in a large proportion of PNE families and the linkage results suggest that such a gene is located on chromosome 12q.

Genetic counselling: the psychological impact of meeting patients' expectations.

Abstract: We know little about patients' expectations of genetic counselling, the extent to which these are met, and whether meeting expectations is associated with improved patient outcome. This study describes 131 consultations of patients referred to a regional genetics centre, and documents their expectations, the extent to which these are met, and the predictors and consequences of expectations being met. The outcomes assessed were state anxiety, concern about the problem for which the patient was referred, and satisfaction with information given. Patients came to genetic counselling expecting information (79%), explanation (63%), reassurance (50%), advice (50%), and help in making decisions (30%). The majority got what they were expecting: 74% had their expectation for information met, 56% had their expectation for explanation met, 60% had their expectation for reassurance met, 61% had their expectation for advice met, and 73% had their expectation for help with making decisions met. Patient expectations, and whether or not these were met, were not predicted by any of the patient or counsellor variables measured. When patients' expectations for reassurance and advice were met, patients were less concerned and their anxiety level was more reduced than when such expectations were not met. Meeting patients' expectations for information, explanation, or help with decision making were not associated with better outcomes. Explanations for these results and implications for the practice of genetic counselling are discussed.

Mutational diversity and hot spots in the alpha-sarcoglycan gene in autosomal recessive muscular dystrophy (LGMD2D).

Abstract: Sarcoglycanopathies are a genetically heterogeneous group of autosomal recessive muscular dystrophies in which the primary defect may reside in any of the genes coding for the different partners of the sarcolemmal sarcoglycan (SG) complex: the alpha-SG (LGMD2D at 17q21.2), the beta-SG (LGMD2E at 4q12), the gamma-SG (LGMD2C at 13q12), and the delta-SG (LGMD2F at 5q33). We report a series of 20 new unrelated families with 14 different mutations in the alpha-SG gene. Along with the mutations that we previously reported this brings our cohort of patients with alpha-sarcoglycanopathy to a total of 31 unrelated patients, carrying 25 different mutations. The missense mutations reside in the extracellular domain of the protein. Five of 15 missense mutations, carried by unrelated subjects on different haplotype backgrounds and of widespread geographical origins, account for 58% of the mutated chromosomes, with a striking prevalence of the R77C substitution (32%). The severity of the disease varies strikingly and correlates at least in part with the amount of residual protein and the type of mutation. The recurrent R284C substitution is associated with a benign disease course.

Multiple lentigines syndrome (LEOPARD syndrome or progressive cardiomyopathic lentiginosis).

Abstract: The multiple lentigines syndrome is an autosomal dominant condition which has many similarities to Noonan syndrome, except in the most striking feature from which its name is derived. The less neutral but very apt mnemonic, LEOPARD syndrome, was first used by Gorlin et al to whom the major debt in the definition of this syndrome lies, that is, Lentigines, ECG abnormalities, Ocular hypertelorism/Obstructive cardiomyopathy, Pulmonary valve stenosis, Abnormalities of genitalia in males, Retardation of growth, and Deafness. Not previously included in the mnemonic is cardiomyopathy which is an important feature because it is associated with significant mortality.

A simplified assay for the arylamine N-acetyltransferase 2 polymorphism validated by phenotyping with isoniazid.

Abstract: Human arylamine N-acetyltransferase (NAT) activity is determined by two distinct genes, NAT1 and NAT2, and the classical acetylation polymorphism in NAT2 has been associated with a variety of disorders, including lupus erythematosus and arylamine induced cancers. Over 50% of the white population exhibit a slow acetylator phenotype. The genetic basis of the defect has been identified and several DNA based assays are available for genotyping studies. We present here a simplified, rapid PCR based assay for the identification of the major slow acetylator genotypes and validate it using isoniazid as probe drug. This assay was 100% predictive of phenotype. The three genotypes (homozygous mutated, heterozygous, and homozygous rapid) corresponded to a trimodal distribution of Ac-INH/INH metabolic ratios (slow, intermediate, and rapid) without overlapping.

Genetic epidemiology of muscular dystrophies resulting from sarcoglycan gene mutations.

Abstract: BACKGROUND: The autosomal recessive limb-girdle muscular dystrophies (LGMDs) are a group of genetically heterogeneous muscle diseases characterised by progressive proximal limb muscle weakness. Six different loci have been mapped and pathogenetic mutations in the genes encoding the sarcoglycan complex components (alpha-, beta-, gamma-, and delta-sarcoglycan) have been documented. LGMD patients affected with primary "sarcoglycanopathies" are classified as LGMD2D, 2E, 2C, and 2F, respectively. METHODS: A geographical area in north east Italy (2,319,147 inhabitants) was selected for a genetic epidemiological study on primary sarcoglycanopathies. Within the period 1982 to 1996, all patients living in this region and diagnosed with muscular dystrophy were seen at our centre. Immunohistochemical and immunoblot screening for alpha-sarcoglycan protein deficiency was performed on all muscle biopsies from patients with a progressive muscular dystrophy of unknown aetiology and normal dystrophin. Sarcoglycan mutation analyses were conducted on all patient muscle biopsies shown to have complete or partial absence of alpha-sarcoglycan immunostaining or a decreased quantity of alpha-sarcoglycan protein on immunoblotting. RESULTS: Two hundred and four patient muscle biopsies were screened for alpha-sarcoglycan protein deficiency and 18 biopsies showed a deficiency. Pathogenetic mutations involving one gene for sarcoglycan complex components were identified in 13 patients: alpha-sarcoglycan in seven, beta-sarcoglycan in two, gamma-sarcoglycan in four, and none in the delta-sarcoglycan gene. The overall prevalence of primary sarcoglycanopathies, as of 31 December 1996, was estimated to be 5.6 x 10(-6) inhabitants. CONCLUSION: The prevalence rate estimated in this study is the first to be obtained after biochemical and molecular genetic screening for sarcoglycan defects.

Fragile X syndrome is less common than previously estimated.

Abstract: In 1986, a population study of school children in the city of Coventry gave an overall prevalence in males and females for fragile X syndrome of 1/952 The 29 children diagnosed as having fragile X syndrome in this study have been re-evaluated with molecular diagnostic techniques Eighteen of the original 29 children have been found not to have the expansion of the FMR1 gene associated with fragile X syndrome Revised prevalence figures have been calculated giving rise to an overall prevalence figure of 1/2720 (range 1/2198-1/3089) If the four children lost to follow up are also assumed not to have the fragile X syndrome, the revised prevalence figure was 1/5714 (range 1/4762-1/6349) Clinical review of boys with severe mental retardation from this and a subsidiary study show that the clinical features of head circumference greater than the 50th centile, testicular volume greater than the 50th centile, and IQ between 35 and 70 remain helpful in distinguishing boys with fragile X syndrome from those who have non-specific mental retardation

Epigenetic modification and uniparental inheritance of H19 in Beckwith-Wiedemann syndrome.

Abstract: Beckwith-Wiedemann syndrome (BWS) is a congenital overgrowth syndrome associated with a characteristic pattern of visceromegaly and predisposition to childhood tumours. BWS is a genetically heterogeneous disorder; most cases are sporadic but approximately 15% are familial and a small number of BWS patients have cytogenetic abnormalities involving chromosome 11p15. Genomic imprinting effects have been implicated in familial and non-familial BWS. We have investigated the molecular pathology of 106 sporadic BWS cases; 17% (14/83) of informative cases had uniparental disomy (UPD) for chromosome 11p15.5. In each case UPD appeared to result from a postzygotic event resulting in mosaicism for segmental paternal isodisomy. The critical region for isodisomy was refined to a 25 cM interval between D11S861 and D11S2071 which contained the IGF2, H19, and p57(KIP2) genes. In three cases isodisomy for 11q markers was detected but this did not extend further than 11q13-q21 suggesting that complete chromosome 11 disomy may not produce a BWS phenotype. The allele specific methylation status of the H19 gene was investigated in 80 sporadic BWS cases. All 13 cases with UPD tested displayed hypermethylation consistent with an excess of paternal H19 alleles. In addition, five of 63 (8%) cases with normal biparental inheritance had H19 hypermethylation consistent with an "imprinting centre" mutation (ICM) or "imprinting error" (IE) lesion. The phenotype of patients with putative ICM/IE mutations was variable and overlapped with that of non-UPD sporadic BWS cases with normal H19 methylation. However, exomphalos was significantly (p < 0.05) more common in the latter group. These findings may indicate differential effects on the expression of imprinted genes in chromosome 11p15 according to the precise molecular pathology. Analysis of H19 methylation is useful for the diagnosis of both UPD or altered imprinting in BWS and shows that a variety of molecular mechanisms may cause relaxation of IGF2 imprinting in BWS.

Craniosynostosis associated with FGFR3 pro250arg mutation results in a range of clinical presentations including unisutural sporadic craniosynostosis.

Abstract: Several mutations involving the fibroblast growth factor receptor (FGFR) gene family have been identified in association with phenotypically distinct forms of craniosynostosis. One such point mutation, resulting in the substitution of proline by arginine in a critical region of the linker region between the first and second immunoglobulin-like domains, is associated with highly specific phenotypic consequences in that mutation at this point in FGFR1 results in Pfeiffer syndrome and analogous mutation in FGFR2 results in Apert syndrome. We now show that a much more variable clinical presentation accompanies analogous mutation in the FGFR3 gene. Specifically, mental retardation, apparently unrelated to the management of the craniosynostosis, appears to be a variable clinical consequence of this FGFR3 mutation.

Psychological distress in applicants for predictive DNA testing for autosomal dominant, heritable, late onset disorders. The Rotterdam/Leiden Genetics Workgroup.

Abstract: In a comparative study on the effects of predictive DNA testing for late onset disorders, pre-test psychological distress was assessed in people at risk for Huntington's disease (HD, n = 41), cerebral haemorrhage (HCHWA-D, n = 9), breast and ovarian cancer (HBOC, n = 24), and polyposis coli (FAP, n = 45). Partners, if available, also participated in the study. Distress was measured with the subscales Intrusion and Avoidance of the Impact of Event Scale. People at risk for the neurodegenerative disorders reported more avoidance than those at risk for the cancer syndromes. People at risk for FAP and partners of those at risk for HBOC reported less intrusion than the others at risk and the other partners. Subjects who were more distressed reported more experiences with the disease in close relatives, the disease having a great impact on their lives, having considerations against predictive testing, expecting that being identified as a gene carrier would have adverse effects, and expecting relief after being identified as a non-carrier. Test candidates who expected an increase of personal problems showed higher avoidance, whereas those who could better anticipate future life as a carrier had higher intrusion levels. Generally, subjects with high distress levels are of more concern to the healthcare professional than those with low distress levels. However, high distress may reflect worrying as a mental preparation for the test result, whereas low distress may indicate denial-avoidance behaviour and poor anticipation of the test outcome. In pre-test counselling sessions, this should be acknowledged and addressed.

De Lange syndrome: subjective and objective comparison of the classical and mild phenotypes.

Abstract: Classical de Lange syndrome presents with a striking face, pronounced growth and mental retardation, and variable limb deficiencies. Over the past five years, a mild variant has been defined, with less significant psychomotor retardation, less marked pre- and postnatal growth deficiency, and an uncommon association with major malformations, although mild limb anomalies may be present. We have evaluated 43 subjects with de Lange syndrome, 30 with classical features, aged from birth to 21 years, and 13 with the mild phenotype, aged from 18 months to 30 years. In addition to assessment of gestalt and facial change with time, detailed craniofacial measurements have been obtained on each subject and composite pattern profiles compiled. The characteristic face of classical de Lange syndrome is present at birth and changes little throughout life, although there is some lengthening of the face with age and the jaw becomes squared. In mild de Lange syndrome, the characteristic classical appearance may be present at birth, but in some subjects it may be two or three years before the typical face is obvious. In general, the overall impression is less striking, perhaps because of increased facial expression and greater alertness. With age, the face loses the characteristic appearance, the nasal height increases, the philtrum does not seem as long, and the upper vermilion is full and everted, although the crescent shaped mouth with downturned corners remains. Eyebrows may be full and bushy. Objective comparison of the face in mild and classical de Lange syndrome, through the use of craniofacial pattern profiles, shows marked similarity of patterns at 4 to 9 years; both groups have microbrachycephaly, but the individual dimensions of the mild group are slightly closer to normal than their classical counterparts. The correlation coefficient is high (0.83). In the adult groups, similarity of patterns remains but is less marked. The normalisation of scores in the mild group is more dramatic. The correlation coefficient is lower (0.71). These objective findings substantiate clinical impressions of a phenotypic dichotomy. Early in life, the craniofacial features in mild de Lange syndrome may be indistinguishable from the classical phenotype and alternative discriminators must be sought in order to identify those subjects in whom the prognosis is more optimistic. Birth weight of more than 2500 g and absence of major limb anomalies may help in this regard.

Pure hereditary spastic paraplegia.

Abstract: Pure hereditary spastic paraplegia (pHSP) The first clear description of pHSP was by Strumpell in 1880,2 who reported a family in which two brothers were affected by a late onset spastic paraplegia. Autosomal dominant inheritance was likely, since their mother was \"a little lame\". Subsequent reports have described autosomal dominant, autosomal recessive, and X linked recessive patterns of inheritance.' 3-12 Autosomal dominant inherit-

Menkes disease: recent advances and new aspects.

Abstract: Copper is the third most abundant trace element in the body, after iron and zinc, and it is required for the normal function of several important copper enzymes. However, the same element in excess is highly toxic and has detrimental effects. Fine regulation of intracellular copper homeostasis is therefore vitally important and disturbance of this balance is reflected in two hereditary disorders, Menkes disease and Wilson disease. In recent years, remarkable progress has been made in this field following the isolation of the defective gene in Menkes disease (MD), which will be the main focus of this review. Progressive neurodegeneration and connective tissue disturbances are the main manifestations ofX linked recessive Menkes disease and

Uptake of genetic testing for cancer predisposition.

Abstract: Although there has been much debate about the uptake and effects of predictive testing for common cancers, such as breast and colon cancer, little has been published on the more classical tumour predisposing conditions, such as von Hippel-Lindau disease and familial adenomatous polyposis. Since 1990 the genetics departments in Manchester and Cambridge have had a genetic register for cancer predisposing syndromes and presymptomatic testing for these conditions has been offered once this has become possible. To investigate the factors that might influence uptake of genetic testing in familial cancer syndromes we have reviewed our experience. Demand for predictive testing has generally been high, but men had a lower uptake (77%) than a comparable group of women (93%) (p < 0.01).

Analysis of spinocerebellar ataxia types 1, 2, 3, and 6, dentatorubral-pallidoluysian atrophy, and Friedreich's ataxia genes in spinocerebellar ataxia patients in the UK.

Abstract: Accurate clinical diagnosis of the spinocerebellar ataxias (SCAs) can be difficult because of overlap in phenotype with other disorders and variation in clinical manifestations. Six SCA loci have been mapped and four disease causing genes identified, in addition to the causative gene for Friedreich's ataxia (FA). All of the identified mutations are expansions of trinucleotide repeat tracts. The SCA2 and SCA6 genes were published recently. The extent of the normal CAG size ranges at these loci and the relative frequencies of the known causes of SCA in the UK are not known. This study first investigated the normal size ranges of the SCA2 and SCA6 loci by genotyping control populations of West African and South African subjects, since African populations generally show the greatest allelic diversity. We found one allele larger than the previously determined normal range for SCA2, and our results at the SCA6 locus agreed with the previously reported normal range. The second component of the study assessed the relative frequencies of the SCA1, 2, 3, and 6, DRPLA, and FA trinucleotide repeat mutations in 146 patients presenting with SCA-like symptoms referred to genetic diagnostic laboratories in the UK. We detected mutations in 14% of patients referred with a diagnosis of autosomal dominant SCA, and in 15% of patients referred with spinocerebellar ataxia where we did not have sufficient family history data available to allow categorisation as familial or sporadic cases. Friedreich's ataxia accounted for 3% of the latter category of cases in our sample, but the most common causes of SCA were SCA2 and SCA6.

RDS/peripherin gene mutations are frequent causes of central retinal dystrophies.

Abstract: Patients from 76 independent families with various forms of mostly central retinal dystrophies were screened for mutations in the RDS/peripherin gene by means of SSCP analysis and direct DNA sequencing. Two nonsense mutations (Gln239ter, Tyr285ter), five missense mutations (Arg172Trp, Lys197Glu, Gly208Asp, Trp246Arg, Ser289Leu), and one single base insertion (Gly208insG), heterozygous in all cases, were detected. Only one of these mutations, Arg172Trp, has been reported previously. Cosegregation of the mutation with the disease phenotype could be established in selected families. Other missense mutations were excluded from a panel of 55-75 control subjects. The patients showed remarkable variation in phenotype and disease expression not only between cases with different mutations but also between affected members of the same family. This study indicates that RDS/peripherin mutations are a frequent cause of various types of central retinal dystrophies and that the RDS/peripherin gene exhibits a broad spectrum of allelic mutations. Comparative analysis of known mutations allowed us to hypothesise that the deleterious effect of RDS/peripherin gene mutations is the result of different molecular mechanisms.

Paternally inherited duplications of 11p15.5 and Beckwith-Wiedemann syndrome.

Abstract: We present a three generation family in which a father and son have a balanced chromosome translocation between the short arms of chromosomes 5 and 11 (karyotype 46,XY,t(5;11)(p15.3;p15.3)). Two family members have inherited the unbalanced products of this translocation and are trisomic for chromosome 11p15.3-->pter and monosomic for chromosome 5p15.3-->pter (karyotype 46,XY,der(5)t(5;11)(p15.3;p15.3)pat). Paternally derived duplications of 11p15.5 are associated with Beckwith-Wiedemann syndrome (BWS) and both family members trisomic for 11p15.5 had prenatal overgrowth (birth weights >97th centile), macroglossia, coarse facial features, and broad hands. We review the clinical features of BWS patients who have a paternally derived duplication of 11p15.5 and provide evidence for a distinct pattern of dysmorphic features in those with this chromosome duplication. Interestingly, our family is the fifth unrelated family to be reported with a balanced reciprocal translocation between the short arms of chromosomes 5 and 11. The apparently non-random nature of this particular chromosome translocation is suggestive of sequence homology between the two chromosome regions involved in the translocation.

Nasu-Hakola syndrome: polycystic lipomembranous osteodysplasia with sclerosing leucoencephalopathy and presenile dementia.

Abstract: Presenile dementia of genetic origin is often attributed to Alzheimer's disease. This disorder remains by far the commonest cause of early dementia. Pick disease and prion protein disorders are usually discussed in the differential diagnosis. We review here Nasu-Hakola syndrome (OMIM 221770), another unusual cause of presenile intellectual deterioration, in which neurological impairment occurs together with impressive destructive changes of the skeleton. (7 Med Genet 1997;34:753-757)