F. Giannelli

Bio: F. Giannelli is an academic researcher from Guy's Hospital. The author has contributed to research in topics: Haemophilia B & Haemophilia. The author has an hindex of 7, co-authored 9 publications receiving 458 citations. Previous affiliations of F. Giannelli include Lund University & Guy's and St Thomas' NHS Foundation Trust.

Haemophilia B mutations in a complete Swedish population sample: a test of new strategy for the genetic counselling of diseases with high mutational heterogeneity.

Abstract: Carrier and prenatal diagnosis based on the identification of the gene defect (direct diagnosis) increases the proportion of haemophilia B families that can be offered precise genetic counselling from the 50-60% attainable by DNA markers, to 100%, and they also provide information on the molecular biology of the disease. We propose that in order to maximize the practical and scientific benefits of direct diagnosis the gene defect of complete (possibly national) populations of patients should be characterized and the information stored in appropriate confidential databases. We demonstrate the feasibility of such a strategy by characterizing the mutations of all the patients registered with the Malmo haemophilia centre. These patients (44♂ and 1♀) are from 45 unrelated families and 24 (53%) have negative family history. The 25 patients with similar reduction of factor IX:C and factor IX:Ag (24♂ + 1♀) have: two gross deletions, three frameshifts, four translation stops, six mutations expected to affect pre-mRNA splicing and 10 amino acid substitutions. The six patients with greater reduction of factor IX:C than factor IX:Ag and the seven with reduced IX:C and normal IX:Ag have only amino acid substitutions. Patients with inhibitors have: one complete deletion, one frameshift and three translation stops. One patient has both a translation stop and a functionally neutral amino acid substitution (His257→Tyr). Characterization of the factor IX mutation was successful in every case, usually entailed 4 person-days work, and has led to the identification of 12 amino acid residues essential for the factor IX structure and function. (Less)

Direct estimate of the haemophilia B (factor IX deficiency) mutation rate and of the ratio of the sex-specific mutation rates in Sweden.

Abstract: Mutation rates for X-linked recessive diseases have so far been estimated indirectly by postulating an equilibrium between the loss of defective genes caused by the low reproductive fitness of affected males and the gain resulting from new mutations. Here, for the first time, we directly estimate both the overall and sex-specific mutation rates for haemophilia B by detecting the gene defect of the families registered at the Malmo Haemophilia Centre. These represent a complete sample of the Swedish haemophilia B population (45 out of 77 pedigrees) and contain 23 families with a single affected male. Fifteen of these males had mothers available for study, and of these mothers, 13 had parents available for study. We show that 3 of the above patients and 10 of their mothers carry new mutations, and by extrapolation calculate that 8 males and 98 females should carry new haemophilia B mutations in the Swedish population (8.52 × 106 individuals). This leads to the following estimate of the mutation rates: overall μ = 4.1 × 10-6; male specific v = 2.1 × 10-5; and female specific u = 1.9 × 10-6. The ratio of such male to female specific mutation rates is thus v/u = 11.

Moderate haemophilia B in a female carrier caused by preferential inactivation of the paternal X chromosome.

Abstract: The case of a female with moderate haemophilia B is reported. She is the only affected member of her family, and factor IX RFLP analysis shows her to have inherited no maternal markers for polymorphisms located in the first intron and 8 Kb 3' of the polyadenylation signal (DdeI and HhaI, respectively). This clearly indicates a deletion involving at least the last 7 exons of the factor IX gene. Her other factor IX gene inherited from her healthy father is normal as her son is also healthy. This suggests the patient's haemophilia to be due to gross bias in the proportion of factor IX-producing cells with an inactive paternal X chromosome. Methylation studies on the 5' region of the PGK gene show that virtually all the patient's lymphocytes carry a hypermethylated and presumably an inactive paternal X chromosome. The reason for this bias in the activity of her two X chromosomes is not clear, as no chromosomal alterations were found.

Haplotype analysis of identical factor IX mutants using PCR.

Abstract: We have detected the mutations in the factor IX genes from all of the haemopllilia B patients registered at Malmo haemophilia centre (45) and are currently examining the entire UK haemophilia B population. From these studies we have found 13 base substitutions which have recurred in 1-6 other, presumably unrelated, patients. In order to determine the minimum number of independent repeats of each mutation we have used PCR to examine the five factor IX polymorphisms forming the most informative combinations and we have characterised thc haplotype of each patient. Patients with different haplotypes are assumed to be unrelated and thus to carry independent mutations. All but one of thc 13 mutations occur in at least 2 haplotypes thus pinpointing 12 mutational hotspots and mutations that can be clearly considered detrimental. Two of the 13 substitutions occur at non-CpG sites. (Less)

The origins, patterns and implications of human spontaneous mutation

Abstract: The germline mutation rate in human males, especially older males, is generally much higher than in females, mainly because in males there are many more germ-cell divisions. However, there are some exceptions and many variations. Base substitutions, insertion-deletions, repeat expansions and chromosomal changes each follow different rules. Evidence from evolutionary sequence data indicates that the overall rate of deleterious mutation may be high enough to have a large effect on human well-being. But there are ways in which the impact of deleterious mutations can be mitigated.

WFH Guidelines for the Management of Hemophilia, 3rd edition

Abstract: Alok Srivastava 1 | Elena Santagostino 2 | Alison Dougall 3 | Steve Kitchen 4 | Megan Sutherland 5 | Steven W. Pipe 6 | Manuel Carcao 7 | Johnny Mahlangu 8 | Margaret V. Ragni 9 | Jerzy Windyga 10 | Adolfo Llinás 11 | Nicholas J. Goddard 12 | Richa Mohan 13 | Pradeep M. Poonnoose 14 | Brian M. Feldman 15 | Sandra Zelman Lewis 16 | H. Marijke van den Berg 17 | Glenn F. Pierce 18 | on behalf of the WFH Guidelines for the Management of Hemophilia panelists and co-authors*

Epidemiology of neurofibromatosis type 1

Abstract: The prevalence of neurofibromatosis type 1 (NF1) is about 1/3,000. There are no known ethnic groups in which NF1 does not occur or is unusually common. The prevalence is somewhat higher in young children than in adults, a difference that probably results at least in part from the early death of some NF1 patients. NF1 is fully penetrant in adults, but many disease features increase in frequency or severity with age. The reproductive fitness of NF1 patients is reduced by about one-half. About half of all cases result from new mutations. The estimated rate of new NF1 mutations is unusually high, but the basis for this high mutation rate is not known. Am. J. Med. Genet. (Semin. Med. Genet.) 89:1-6, 1999.

The high spontaneous mutation rate: Is it a health risk?

Abstract: The human mutation rate for base substitutions is much higher in males than in females and increases with paternal age. This effect is mainly, if not entirely, due to the large number of cell divisions in the male germ line. The mutation-rate increase is considerably greater than expected if the mutation rate were simply proportional to the number of cell divisions. In contrast, those mutations that are small deletions or rearrangements do not show the paternal age effect. The observed increase with the age of the father in the incidence of children with different dominant mutations is variable, presumably the result of different mixtures of base substitutions and deletions. In Drosophila, the rate of mutations causing minor deleterious effects is estimated to be about one new mutation per zygote. Because of a larger number of genes and a much larger amount of DNA, the human rate is presumably higher. Recently, the Drosophila data have been reanalyzed and the mutation-rate estimate questioned, but I believe that the totality of evidence supports the original conclusion. The most reasonable way in which a species can cope with a high mutation rate is by quasi-truncation selection, whereby a number of mutant genes are eliminated by one “genetic death.”