Showing papers by "Wellcome Trust Centre for Human Genetics published in 2003"

Twin concordance and sibling recurrence rates in multiple sclerosis

Abstract: Size and ascertainment constraints often limit twin studies to concordance comparisons between identical and fraternal twins. Here we report the final results of a longitudinal, population-based study of twins with multiple sclerosis (MS) in Canada. Bias was demonstrably minimized, and an estimated 75% of all Canadian MS twin pairs were ascertained, giving a sample sufficiently large (n = 370) to permit additional informative comparisons. Twinning was not found to affect prevalence, and twins with MS did not differ from nontwins for DR15 allele frequency nor for MS risk to their siblings. Probandwise concordance rates of 25.3% (SE ± 4.4) for monozygotic (MZ), 5.4% (±2.8) for dizygotic (DZ), and 2.9% (±0.6) for their nontwin siblings were found. MZ twin concordance was in excess of DZ twin concordance. The excess concordance in MZ was derived primarily from like-sexed female pairs with a probandwise concordance rate of 34 of 100 (34 ± 5.7%) compared with 3 of 79 (3.8 ± 2.8%) for female DZ pairs. We did not demonstrate an MZ/DZ difference in males, although the sample size was small. We observed a 2-fold increase in risk to DZ twins over nontwin siblings of twins, but the difference was not significant.

Structural organization of authentic, mature HIV-1 virions and cores.

Abstract: Mature, infectious HIV-1 particles contain a characteristic cone-shaped core that encases the viral RNA and replication proteins. The architectures of mature virions and isolated cores were studied using cryo-electron microscopy. The average size ( approximately 145 nm) of the virion was unchanged during maturation. Most virions contained a single core but roughly one-third contained two or more cores. Consideration of the capsid protein concentration during core assembly indicated that core formation in vivo is template-mediated rather than concentration-driven. Although most cores were conical, 7% were tubular. These displayed a stacked-disc arrangement with 7-, 8-, 9- or 10-fold axial symmetry. Layer line filtration of these images showed that the capsid subunit arrangement is consistent with a 9.6 nm hexamer resembling that previously seen in the helical tubes assembled from purified capsid protein. A common reflection (1/3.2 nm) shared between the tubular and conical cores suggested they share a similar organization. The extraordinary flexibility observed in the assembly of the mature core appears to be well suited to accommodating variation and hence there may be no single structure for the infectious virion.

The Genetic Legacy of the Mongols

Abstract: We have identified a Y-chromosomal lineage with several unusual features. It was found in 16 populations throughout a large region of Asia, stretching from the Pacific to the Caspian Sea, and was present at high frequency: ∼8% of the men in this region carry it, and it thus makes up ∼0.5% of the world total. The pattern of variation within the lineage suggested that it originated in Mongolia ∼1,000 years ago. Such a rapid spread cannot have occurred by chance; it must have been a result of selection. The lineage is carried by likely male-line descendants of Genghis Khan, and we therefore propose that it has spread by a novel form of social selection resulting from their behavior.

Genetic polymorphisms and personality in healthy adults: a systematic review and meta-analysis.

Abstract: A meta-analysis was conducted on studies reporting data on associations between candidate genes and human personality. Studies reporting data for psychiatric populations (including organic disease and substance abuse) were excluded. A total of 46 studies contributed to the analysis. Pooled data using a fixed-effects model suggested significant associations between the 5HTT LPR, DRD4 c>t, DRD4 length, DRD2 A1/A2, DRD3 A1/A2 polymorphisms and personality traits. A multivariate analysis using a mixed-effects model and including age, sex and predominant ethnicity as covariates was applied to the analyses of 5HTT LPR and DRD4 length polymorphism data. Only the association between the 5HTT LPR polymorphism and avoidance traits remained significant (P=0.038). However, sensitivity analyses excluding data from studies reporting allele frequencies not in Hardy-Weinberg equilibrium and unpublished data resulted in this association no longer being significant. Implications for the design of future association studies of human personality are discussed, including the likely sample sizes that will be required to achieve sufficient power and the potential role of moderating variables such as sex.

FOXP2 expression during brain development coincides with adult sites of pathology in a severe speech and language disorder.

Abstract: Disruption of FOXP2, a gene encoding a forkhead-domain transcription factor, causes a severe developmental disorder of verbal communication, involving profound articulation deficits, accompanied by linguistic and grammatical impairments. Investigation of the neural basis of this disorder has been limited previously to neuroimaging of affected children and adults. The discovery of the gene responsible, FOXP2, offers a unique opportunity to explore the relevant neural mechanisms from a molecular perspective. In the present study, we have determined the detailed spatial and temporal expression pattern of FOXP2 mRNA in the developing brain of mouse and human. We find expression in several structures including the cortical plate, basal ganglia, thalamus, inferior olives and cerebellum. These data support a role for FOXP2 in the development of corticostriatal and olivocerebellar circuits involved in motor control. We find intriguing concordance between regions of early expression and later sites of pathology suggested by neuroimaging. Moreover, the homologous pattern of FOXP2/Foxp2 expression in human and mouse argues for a role for this gene in development of motor-related circuits throughout mammalian species. Overall, this study provides support for the hypothesis that impairments in sequencing of movement and procedural learning might be central to the FOXP2-related speech and language disorder.

Pathogenic bacteria attach to human fibronectin through a tandem beta-zipper.

Abstract: Staphylococcus aureus and Streptococcus pyogenes, two important human pathogens, target host fibronectin (Fn) in their adhesion to and invasion of host cells1, 2. Fibronectin-binding proteins (FnBPs), anchored in the bacterial cell wall, have multiple Fn-binding repeats3 in an unfolded4, 5 region of the protein. The bacterium-binding site in the amino-terminal domain (1–5F1) of Fn contains five sequential Fn type 1 (F1) modules. Here we show the structure of a streptococcal (S. dysgalactiae) FnBP peptide (B3)6, 7 in complex with the module pair 1F12F1. This identifies 1F1- and 2F1-binding motifs in B3 that form additional antiparallel -strands on sequential F1 modules—the first example of a tandem -zipper. Sequence analyses of larger regions of FnBPs from S. pyogenes and S. aureus reveal a repeating pattern of F1-binding motifs that match the pattern of F1 modules in 1–5F1 of Fn. In the process of Fn-mediated invasion of host cells, therefore, the bacterial proteins seem to exploit the modular structure of Fn by forming extended tandem -zippers. This work is a vital step forward in explaining the full mechanism of the integrin-dependent2, 8 FnBP-mediated invasion of host cells.

Positional cloning of a novel gene influencing asthma from Chromosome 2q14

Abstract: Asthma is a common disease in children and young adults. Four separate reports have linked asthma and related phenotypes to an ill-defined interval between 2q14 and 2q32 (refs. 1-4), and two mouse genome screens have linked bronchial hyper-responsiveness to the region homologous to 2q14 (refs. 5,6). We found and replicated association between asthma and the D2S308 microsatellite, 800 kb distal to the IL1 cluster on 2q14. We sequenced the surrounding region and constructed a comprehensive, high-density, single-nucleotide polymorphism (SNP) linkage disequilibrium (LD) map. SNP association was limited to the initial exons of a solitary gene of 3.6 kb (DPP10), which extends over 1 Mb of genomic DNA. DPP10 encodes a homolog of dipeptidyl peptidases (DPPs) that cleave terminal dipeptides from cytokines and chemokines, and it presents a potential new target for asthma therapy.

Positional cloning of a quantitative trait locus on chromosome 13q14 that influences immunoglobulin E levels and asthma.

Abstract: Atopic or immunoglobulin E (IgE)-mediated diseases include the common disorders of asthma, atopic dermatitis and allergic rhinitis. Chromosome 13q14 shows consistent linkage to atopy and the total serum IgE concentration. We previously identified association between total serum IgE levels and a novel 13q14 microsatellite (USAT24G1; ref. 7) and have now localized the underlying quantitative-trait locus (QTL) in a comprehensive single-nucleotide polymorphism (SNP) map. We found replicated association to IgE levels that was attributed to several alleles in a single gene, PHF11. We also found association with these variants to severe clinical asthma. The gene product (PHF11) contains two PHD zinc fingers and probably regulates transcription. Distinctive splice variants were expressed in immune tissues and cells.

Chromosome-wide distribution of haplotype blocks and the role of recombination hot spots.

Abstract: Recent studies of human populations suggest that the genome consists of chromosome segments that are ancestrally conserved ('haplotype blocks'; refs. 1-3) and have discrete boundaries defined by recombination hot spots(4,5). Using publicly available genetic markers(6), we have constructed a first-generation haplotype map of chromosome 19. As expected for this marker density(7), approximately one-third of the chromosome is encompassed within haplotype blocks. Evolutionary modeling of the data indicates that recombination hot spots are not required to explain most of the observed blocks, providing that marker ascertainment and the observed marker spacing are considered. In contrast, several long blocks are inconsistent with our evolutionary models, and different mechanisms could explain their origins.

In vivo characterization of regulatory polymorphisms by allele-specific quantification of RNA polymerase loading.

Abstract: In vivo characterization of regulatory polymorphisms is a key requirement for next-generation human genetic analysis. Here we describe haploChIP, a method that uses chromatin immunoprecipitation (ChIP) and mass spectrometry to identify differential protein-DNA binding in vivo associated with allelic variants of a gene. We demonstrate this approach with the imprinted gene SNRPN. HaploChIP showed close correlation between the level of bound phosphorylated RNA polymerase II at the SNRPN locus and allele-specific expression. Application of the approach to the TNF/LTA locus identified functionally important haplotypes that correlate with allele-specific transcription of LTA. The haploChIP method may be useful in high-throughput screening for common DNA polymorphisms that affect gene regulation in vivo.

Polymorphisms in interferon-induced genes and the outcome of hepatitis C virus infection: roles of MxA, OAS-1 and PKR

Abstract: Interferon stimulates the expression of a number of genes encoding enzymes with antiviral activities, including myxovirus resistance-1 (MxA), 2-5-oligoadenylate synthetase 1 (OAS-1) and double-stranded RNA-dependent protein kinase (PKR). We examined whether polymorphisms in these genes influenced the outcome of hepatitis C virus (HCV) infection. We observed a lower frequency of the GG genotype at position −88 in the MxA gene promoter in self-limiting HCV infection (OR=0.56; 95% CI: 0.35–0.8; P=0.010) and in nonresponders to therapy (OR=0.49; 95% CI: 0.25–0.95; P=0.020). This genotype predominantly influenced the outcome of treatment in patients with viral genotype 1 (OR=0.22 95% CI: 0.07–0.67; P=0.002). A polymorphism in the 3′-untranslated region of the OAS-1 gene was associated with outcome of infection (GG genotype less frequent in self-limiting infection: OR=0.43; 95% CI: 0.21–0.86; P=0.010). A polymorphism at position −168 in the promoter region of the PKR gene was associated with self-limiting infection (CT genotype: OR=2.75; 95% CI: 1.45–5.24; P=0.002). Further associations were found with a CGG trinucleotide repeat in the 5′UTR region of the PKR gene. Polymorphisms in the interferon-induced genes, MxA, OAS-1 and PKR appear thus associated with HCV outcome.

A genomewide scan for attention-deficit/hyperactivity disorder in an extended sample: suggestive linkage on 17p11.

Abstract: Attention-deficit/hyperactivity disorder (ADHD [MIM 143465]) is a common, highly heritable neurobehavioral disorder of childhood onset, characterized by hyperactivity, impulsivity, and/or inattention. As part of an ongoing study of the genetic etiology of ADHD, we have performed a genomewide linkage scan in 204 nuclear families comprising 853 individuals and 270 affected sibling pairs (ASPs). Previously, we reported genomewide linkage analysis of a “first wave” of these families composed of 126 ASPs. A follow-up investigation of one region on 16p yielded significant linkage in an extended sample. The current study extends the original sample of 126 ASPs to 270 ASPs and provides linkage analyses of the entire sample, using polymorphic microsatellite markers that define an ∼10-cM map across the genome. Maximum LOD score (MLS) analysis identified suggestive linkage for 17p11 (MLS=2.98) and four nominal regions with MLS values >1.0, including 5p13, 6q14, 11q25, and 20q13. These data, taken together with the fine mapping on 16p13, suggest two regions as highly likely to harbor risk genes for ADHD: 16p13 and 17p11. Interestingly, both regions, as well as 5p13, have been highlighted in genomewide scans for autism.

Analysis of Quantitative Trait Loci That Influence Animal Behavior

Abstract: Behavioral differences between inbred strains of mice and rats have a genetic basis that can now be dissected using quantitative trait locus (QTL) analysis. Over the last 10 years, a large number of genetic loci that influence behavior have been mapped. In this article I review what that information has revealed about the genetic architecture of behavior. I show that most behaviors are influenced by QTL of small effect, each contributing to less than 10% of the variance of a behavioral trait. The small effect of each QTL on behavioral variation suggests that the mutational spectrum is different from that which results in Mendelian disorders. Regions of DNA should be appropriately prioritized to find the molecular variants, for instance by looking at sequences that control the level of gene expression rather than variants in coding regions. While the number of allelic loci that can contribute to a trait is large, this is not necessarily the case: the analysis of selected strains shows that a remarkably small number of QTL can explain the bulk of the genetic variation in behavior. I conclude by arguing that genetic mapping has more to offer than a starting point for positional cloning projects. With advances in multivariate analyses, mapping can also test hypotheses about the psychological processes that give rise to behavioral variation.

Efficient selective screening of haplotype tag SNPs.

Abstract: Haplotypes defined by common single nucleotide polymorphisms (SNPs) have important implications for mapping of disease genes and human traits. Often only a small subset of the SNPs is sufficient to capture the full haplotype information. Such subsets of markers are called haplotype tagging SNPs (htSNPs). Although htSNPs can be identified by eye, efficient computer algorithms and flexible interactive software tools are required for large datasets such as the human genome haplotype map. We describe a java-based program, SNPtagger, which screens for minimal sets of SNP markers to represent given haplotypes according to various user requirements. The program offers several options for inclusion/exclusion of specific markers and presents alternative panels for final selection.

Linkage Analysis of Extremely Discordant and Concordant Sibling Pairs Identifies Quantitative-Trait Loci That Influence Variation in the Human Personality Trait Neuroticism

Abstract: Several theoretical studies have suggested that large samples of randomly ascertained siblings can be used to ascertain phenotypically extreme individuals and thereby increase power to detect genetic linkage in complex traits. Here, we report a genetic linkage scan using extremely discordant and concordant sibling pairs, selected from 34,580 sibling pairs in the southwest of England who completed a personality questionnaire. We performed a genomewide scan for quantitative-trait loci (QTLs) that influence variation in the personality trait of neuroticism, or emotional stability, and we established genomewide empirical significance thresholds by simulation. The maximum pointwise P values, expressed as the negative logarithm (base 10), were found on 1q (3.95), 4q (3.84), 7p (3.90), 12q (4.74), and 13q (3.81). These five loci met or exceeded the 5% genomewide significance threshold of 3.8 (negative logarithm of the P value). QTLs on chromosomes 1, 12, and 13 are likely to be female specific. One locus, on chromosome 1, is syntenic with that reported from QTL mapping of rodent emotionality, an animal model of neuroticism, suggesting that some animal and human QTLs influencing emotional stability may be homologous.

Meta-analysis and a large association study confirm a role for calpain-10 variation in type 2 diabetes susceptibility.

Abstract: To the Editor: Variation in the calpain-10 gene (CAPN10 [MIM 605286]) was recently linked and associated with type 2 diabetes mellitus (T2DM) susceptibility (Horikawa et al. 2000). The initial linkage of T2DM to chromosome 2 was found in a population of Mexican Americans from Starr County, Texas (Hanis et al. 1996). Specific combinations of three intronic variants, designated “SNP-43,” “SNP-19,” and “SNP-63,” that capture most of the haplotype diversity at CAPN10 were associated with a three-fold increased risk of T2DM in this population and could account for the observed linkage (Horikawa et al. 2000). Subsequent association and linkage studies of these three polymorphisms in other populations have produced conflicting results, with association being observed in some populations (Baier et al. 2000 [Pima Indian]; Cassell et al. 2002 [South Indian]; Garant et al. 2002 [African American]; Malecki et al. 2002 [Polish]; Orho-Melander et al. 2002 [Finnish/Botnia]), but not others (Evans et al. 2001 [British]; Hegele et al. 2001 [Oji-Cree Indians]; Tsai et al. 2001 [Samoan]; Xiang et al. 2001 [Chinese]; Daimon et al. 2002 [Japanese]; Elbein et al. 2002 [whites from Utah]; Fingerlin et al. 2002 [Finnish]; Rasmussen et al. 2002 [Danish and Swedish]; Horikawa et al. 2003 [Japanese]). We previously reported that another variant, SNP-44 (designated “CAPN10-g4841T→C”; minor allele frequency 16%), located in intron 3 and 11 bp from SNP-43, was independently associated with T2DM in whites from the United Kingdom (Evans et al. 2001). Further studies have provided tentative support for a role of SNP-44 in T2DM and related traits: associations with polycystic ovary syndrome (Gonzalez et al. 2002) and with measures of oral glucose tolerance (Wang et al. 2002; Tschritter et al. 2003) have been reported. Functional studies suggest that SNP-44 is located in an enhancer element and might affect CAPN10 expression (Horikawa et al. 2000). Also, in the U.K., German, Japanese, and South Indian populations, SNP-44 is in perfect linkage disequilibrium (r2=1) with a missense mutation Thr504Ala (SNP-110) and two polymorphisms in the 5′-UTR (SNP-134 and SNP-135) (Evans et al. 2001; Cassell et al. 2002; Y. Horikawa and P. E. Schwarz, unpublished data). To assess the association of SNP-44 with T2DM more comprehensively, we performed a meta-analysis of all published SNP-44/T2DM association study data. To identify all relevant published studies, we searched PubMed using the keywords “calpain 10,” “diabetes,” “44,” “SNP 44,” “CAPN10,” and “type 2,” in different combinations. When necessary, authors were contacted to obtain exact genotype numbers, so that precise odds ratios (ORs) from each study could be calculated. Our search identified 10 published case/control studies, consisting of 3,303 subjects. The studies were spread across a number of ethnic groups: British (three studies, Evans et al. 2001); Chinese (Wang et al. 2002); Japanese (Daimon et al. 2002; Horikawa et al. 2003); Finnish/Botnia (two studies, Orho-Melander et al. 2002); South Indian (Cassell et al. 2002); and Mexican American (Horikawa et al. 2000). The frequency of the T2DM-associated SNP-44 C allele (allele 2) ranged from 6% in Mexican Americans to 25% in the Botnia I control population. There was no evidence for OR heterogeneity (Q test P=.27), and, although these studies are only a small sample from the many existing T2DM genetic resources, a funnel-plot analysis (Egger et al. 1997) suggested an absence of publication bias (P=.44). A Mantel-Haenszel meta-analysis of these studies showed that the C allele was associated with increased risk of T2DM (OR 1.17 [1.02–1.34], P=.02). Three transmission/disequilibrium tests (TDT) had been performed (Evans et al. 2001; Cassell et al. 2002; Orho-Melander et al. 2002). The combined TDT results demonstrated that the C allele was significantly overtransmitted (117 transmitted vs. 77 not transmitted, P=.004) from heterozygous parents to diabetic offspring. Although this result cannot be considered independent replication, as proband data was included in the case/control meta-analysis from two of the TDT studies (Evans et al. 2001; Cassell et al. 2002), it provides evidence that the association is not due to population stratification. Of the 10 studies in the meta-analysis, only 1 reported a significant (P<.05) association (Evans et al. 2001). However, these studies were small and the mean power to detect an OR of 1.17 at P<.05 was ∼11% (range 5%–14%). In the context of genetic association studies, which test many polymorphisms in numerous candidate genes, a P value of .02 can only be considered evidence suggestive of a real association. We therefore genotyped SNP-44 in an additional 4,213 subjects: 3,274 white European subjects from four case/control studies (one British, two German, and one Czech); 691 Japanese subjects from two case/control studies; and 248 Mexican (mestizo) subjects from Mexico City and Orizaba City from one case/control study. Overall, this provided 2,056 subjects with T2DM and 2,157 controls, and a power of ∼80% to detect an OR of 1.17. Clinical details of the study subjects are presented in table 1; further details are available as supplementary information from the authors. All studies were approved by the relevant ethics committee, and all subjects gave their informed consent. Table 1 Clinical Characteristics of Subjects in Study[Note] When all the studies were combined, there was no evidence for between-studies OR heterogeneity (Q test P=.23); a Mantel-Haenszel fixed-effects model was therefore used for subsequent analysis. Meta-analysis of the new studies gave an OR for the SNP-44 C allele of 1.18 (1.04–1.34), P=.01 (fig. 1). A combined meta-analysis of all previously published data and our new data gave an OR of 1.17 (1.07–1.29), P=.0007. All study populations were in Hardy-Weinberg equilibrium except the T2DM cohort of Horikawa et al. 2003 (P=.005) and the control population of the third Japanese study (P=.02). Although these deviations may be due to random fluctuation and multiple-hypothesis testing, they contributed a large amount to heterogeneity (27% of the Q statistic); excluding these studies, the SNP-44 C allele OR for the new studies was 1.23 (1.07–1.40), P=.003; the overall OR was 1.19 (1.08–1.31), P=.0005. This OR is of similar magnitude to that of E23K (Gloyn et al. 2003; Love-Gregory et al. 2003; Nielsen et al. 2003) and Pro12Ala (Altshuler et al. 2000), the other common variants confirmed as T2DM-susceptibility polymorphisms. An OR of 1.17 is low and may help explain why there is little evidence for linkage of the CAPN10 region to T2DM in most populations. The haplotypes responsible for the CAPN10 linkage seen in the Mexican American population were associated with a higher T2DM OR (∼3.0) and were more likely to be detected by linkage analysis (Horikawa et al. 2000). These haplotypes are less common in other populations. Figure 1 Mantel-Haenszel OR meta-analysis plot (fixed effects) for SNP-44 association with T2DM. Point estimates and 95% CLs for each previously published, new, and combined case/control study. SNP-44 is in perfect linkage disequilibrium (r2=1) with the missense mutation, Thr504Ala, and two SNPs (SNP-134 and SNP-135) in the 5′-UTR and therefore may not be the causal variant. Further haplotype and functional analyses are required to confirm which of these polymorphisms contribute to T2DM susceptibility. In conclusion, our results have confirmed that a CAPN10 haplotype defined by the SNP-44 polymorphism predisposes to T2DM. Meta-analyses of published genetic associations, combined with large replication studies, are a powerful approach to detecting susceptibility variants in common disease.

LEKTI proteolytic processing in human primary keratinocytes, tissue distribution and defective expression in Netherton syndrome

Abstract: SPINK5, encoding the putative multi-domain serine protease inhibitor LEKTI, was recently identified as the defective gene in the severe autosomal recessive ichthyosiform skin condition, Netherton syndrome (NS). Using monoclonal and polyclonal antibodies, we show that LEKTI is a marker of epithelial differentiation, strongly expressed in the granular and uppermost spinous layers of the epidermis, and in differentiated layers of stratified epithelia. LEKTI expression was also demonstrated in normal differentiated human primary keratinocytes (HK) through detection of a 145 kDa full-length protein and a shorter isoform of 125 kDa. Both proteins are N-glycosylated and rapidly processed in a post-endoplasmic reticulum compartment into at least three C-terminal fragments of 42, 65 and 68 kDa, also identified in conditioned media. Processing of the 145 and 125 kDa precursors was prevented in HK by treatment with a furin inhibitor. In addition, in vitro cleavage of the recombinant 145 kDa precursor by furin generated C-terminal fragments of 65 and 68 kDa, further supporting the involvement of furin in LEKTI processing. In contrast, LEKTI precursors and proteolytic fragments were not detected in differentiated HK from NS patients. Defective expression of LEKTI in skin sections was a constant feature in NS patients, whilst an extended reactivity pattern was observed in samples from other keratinizing disorders, demonstrating that loss of LEKTI expression in the epidermis is a diagnostic feature of NS. The identification of novel processed forms of LEKTI provides the basis for future functional and structural studies of fragments with physiological relevance.

Deciphering the genetic basis of speech and language disorders

Abstract: A significant number of individuals have unexplained difficulties with acquiring normal speech and language, despite adequate intelligence and environmental stimulation. Although developmental disorders of speech and language are heritable, the genetic basis is likely to involve several, possibly many, different risk factors. Investigations of a unique three-generation family showing monogenic inheritance of speech and language deficits led to the isolation of the first such gene on chromosome 7, which encodes a transcription factor known as FOXP2. Disruption of this gene causes a rare severe speech and language disorder but does not appear to be involved in more common forms of language impairment. Recent genome-wide scans have identified at least four chromosomal regions that may harbor genes influencing the latter, on chromosomes 2, 13, 16, and 19. The molecular genetic approach has potential for dissecting neurological pathways underlying speech and language disorders, but such investigations are only just beginning.

Carbonic anhydrase XII is a marker of good prognosis in invasive breast carcinoma

Abstract: Hypoxia and pH influence gene expression in tumours, and it is becoming increasingly clear that the pattern of genes expressed by a tumour determines its growth and survival characteristics. Hypoxia-inducible factor-1 (HIF-1) is a key mediator of the cellular response to hypoxia and high HIF-1 expression has been identified as a poor prognostic factor in tumours. Recently, we identified the tumour-associated carbonic anhydrases (CA), CA9 and CA12 as hypoxia-inducible in tumour cell lines. Furthermore, we identified CA IX to be a poor prognostic factor in breast cancer. The aim of this study was to assess the prognostic significance of CA XII. CA XII expression was studied by immunohistochemistry in a series of 103 cases of invasive breast cancer and any association with recognised prognostic factors or relation with the outcome was examined. CA XII expression was present in 77 out of 103 (75%) cases and was associated with lower grade (P=0.001), positive estrogen receptor status (P<0.001), and negative epidermal growth factor receptor status (P<0.001). Furthermore, although CA XII expression was associated with an absence of necrosis (P<0.001), expression of CA XII in some high-grade tumours was induced in regions directly adjacent to morphological necrosis. Additionally, using univariate analysis, CA XII positive tumours were associated with a lower relapse rate (P=0.04) and a better overall survival (P=0.01). In conclusion, CA XII expression is influenced both by factors related to differentiation and hypoxia in breast cancer in vivo and CA XII expression is associated with a better prognosis in an unselected series of invasive breast carcinoma patients.