Biomedical subjects

Anita L DeStefano

Publications and source records attributed to Anita L DeStefano.

18 recordsLinked to original sources

PubMed2025

Domain mapping of disease mutations reveals pathogenic SORL1 variants in Alzheimer's disease.

BACKGROUND: Protein truncating variants (PTVs) in SORL1 are observed almost exclusively in Alzheimer’s Disease (AD) cases, but the effect of rare SORL1 missense variants is unclear. METHODS: To identify high-priority missense variants (HPVs), we applied ‘domain mapping of disease mutations’ for the 637 unique coding SORL1 variants detected in 18,959 AD-cases and 21,893 non-demented controls. RESULTS: In this sample, PTVs and HPVs associated with respectively a 35- and 10-fold increased risk of early onset AD and 17- and 6-fold increased risk of overall AD. The median age at onset (AAO) of PTV- and HPV-carriers was 62 and 64 years, and APOE-genotype contributed to AAO-variability. The median AAO of PTV- and HPV-carriers is ~8–10 years earlier than wild-type SORL1 carriers, matched for APOE-genotype. Specific HPVs are highly penetrant and lead to earlier AAOs than PTVs, suggesting possible dominant negative effects. CONCLUSION: Our results justify a debate on whether HPV carriers should be considered for clinical counseling.

Humans↗

PubMed2025

Frequency of variants in Mendelian Alzheimer's disease genes within the Alzheimer's Disease Sequencing Project.

BackgroundPrior studies examined variants within presenilin-2 (PSEN2), presenilin-1 (PSEN1), and amyloid precursor protein (APP) genes. However, previously-reported clinically-relevant variants and other predicted damaging missense (DM) variants have not been characterized in a newer release of the Alzheimer's Disease Sequencing Project (ADSP).ObjectiveTo characterize previously-reported clinically-relevant variants and DM variants in PSEN2, PSEN1, APP within the participants from the ADSP.MethodsWe identified rare variants (MAF < 1%) in PSEN2, PSEN1, and APP in 14,641 individuals with whole genome sequencing and 16,849 individuals with whole exome sequencing available (Ntotal = 31,490). We additionally curated variants from ClinVar, OMIM, and Alzforum and report carriers of variants in clinical databases as well as predicted DM variants in these genes.ResultsWe detected 31 previously-reported clinically-relevant variants with alternate alleles observed within the ADSP: 4 variants in PSEN2, 25 in PSEN1, and 2 in APP. The overall variant carrier rate for the 31 clinically-relevant variants in the ADSP was 0.3%. We observed that 79.5% of the variant carriers were cases compared to 3.9% were controls. In those with AD, the mean age of onset of AD among carriers of these clinically-relevant variants was 19.6 ± 1.4 years earlier compared with noncarriers (p = 7.8 × 10-57). Additionally, we identified 197 rare variants (MAF < 1%) within ADSP participants not reported in known clinical databases.ConclusionsA small proportion of individuals in the ADSP are carriers of a previously-reported clinically-relevant variant allele for AD and these participants have significantly earlier age of AD onset compared to noncarriers.

Humans↗

PubMed2007

Informative-transmission disequilibrium test (i-TDT): combined linkage and association mapping that includes unaffected offspring as well as affected offspring.

To date, there is no test valid for the composite null hypothesis of no linkage or no association that utilizes transmission information from heterozygous parents to their unaffected offspring as well as the affected offspring from ascertained nuclear families. Since the unaffected siblings also provide information about linkage and association, we introduce a new strategy called the informative-transmission disequilibrium test (i-TDT), which uses transmission information from heterozygous parents to all of the affected and unaffected offspring in ascertained nuclear families and provides a valid chi-square test for both linkage and association. The i-TDT can be used in various study designs and can accommodate all types of independent nuclear families with at least one affected offspring. We show that the transmission/disequilibrium test (TDT) (Spielman et al. [1993] Am. J. Hum. Genet. 52:506-516) is a special case of the i-TDT, if the study sample contains only case-parent trios. If the sample contains only affected and unaffected offspring without parental genotypes, the i-TDT is equivalent to the sibship disequilibrium test (SDT) (Horvath and Laird [1998] Am. J. Hum. Genet. 63:1886-1897. In addition, the test statistic of i-TDT is simple, explicit and can be implemented easily without intensive computing. Through computer simulations, we demonstrate that power of the i-TDT can be higher in many circumstances compared to a method that uses affected offspring only. Applying the i-TDT to the Framingham Heart Study data, we found that the apolipoprotein E (APOE) gene is significantly linked and associated with cross-sectional measures and longitudinal changes in total cholesterol.

Apolipoproteins E↗

PubMed2006

Influence of heterozygosity for parkin mutation on onset age in familial Parkinson disease: the GenePD study.

BACKGROUND: The PARK2 gene at 6q26 encodes parkin, whose inactivation is implicated in an early-onset autosomal recessive form of Parkinson disease (PD). OBJECTIVE: To evaluate the influence of heterozygosity for parkin mutation on onset age in a sample of families with at least 2 PD-affected members. DESIGN: Clinical and genetic study. SETTING: Twenty collaborative clinical sites. PATIENTS: Patients with familial PD collected in the GenePD study. Studied families were selected for (1) affected sibling pairs sharing 2 alleles identical by state at PARK2 (D6S305) or (2) 1 or more family members with onset age younger than 54 years, regardless of D6S305 status. At least 1 member from each of 183 families underwent comprehensive screening for deletion/insertion variants and point mutations in PARK2. MAIN OUTCOME MEASURES: Mutations in the parkin gene were screened by means of single-stranded conformation polymorphism and sequencing in all 12 coding exons and flanking intronic sequences for point mutations and duplex quantitative polymerase chain reaction in all exons for rearrangement, duplication, and deletion. RESULTS: Mutations were found in 23 families (12.6% of those screened). Among the mutation-positive families, 10 (43%) contained compound heterozygotes; 3 (13%), homozygotes; and 10 (43%), heterozygotes. The onset age in patients with parkin gene mutations ranged from 20 to 76 years. Patients with 1 parkin mutation had an 11.7-year age at onset than did patients with none (P = .04), and patients with 2 or more parkin mutations had a 13.2-year decrease in age at onset compared with patients with 1 mutation (P = .04). CONCLUSIONS: These data indicate that parkin mutations are not rare in multiply affected sibships, and that heterozygous mutation carrier status in PARK2 significantly influences age at onset of PD.

Adult↗

PubMed2005

Genome-wide scan for white matter hyperintensity: the Framingham Heart Study.

BACKGROUND AND PURPOSE: White matter hyperintensity (WMH) volume is associated with aging and cerebrovascular disease and has been demonstrated to have a high heritability in the Framingham Heart Study as well as in other studies. We performed a genome-wide linkage analysis to identify chromosomal regions that may harbor genes influencing WMH in a family-based sample of the Framingham Heart Study. METHODS: Brain magnetic resonance scans were performed, and WMH and total cranial volume (TCV) were quantified as previously described on 2259 cohort and offspring participants. The outcome used for linkage analysis was an age specific (within 10-year age groups) z-score for the natural logarithm of the ratio of WMH to TCV. This z-score was based on 2230 individuals after excluding 26 participants with neurological conditions other than stroke and 3 individuals whose ages were out of range. Variance component linkage analysis included 747 individuals (mean age=62.16+/-12.43 years) with both magnetic resonance measure and genotype information in 237 families. Mean percent WMH to TCV was 0.098+/-0.175 with a range of 0.00025% to 1.37% in the linkage analysis subjects. RESULTS: A maximum multipoint logarithm of the odds (LOD) score=3.69, which indicates significant evidence of linkage, was observed at 4 cM on chromosome 4. A suggestive peak with LOD=1.78 was observed at 95 cM on chromosome 17. CONCLUSIONS: We have significant evidence that a gene influencing WMH volume is located on chromosome 4 of the human genome.

Adult↗

PubMed2005

Association of NEDD4L ubiquitin ligase with essential hypertension.

NEDD4L is a ubiquitin ligase that controls cell surface expression of kidney epithelial Na+ channels by ubiquitin-mediated endocytosis and lysosome targeting. Thus, it is a significant determinant of Na+ reabsorption in the distal nephron. The NEDD4L gene is located on human chromosome 18q21 within several blood pressure quantitative trait loci, including those for familial orthostatic hypotension, essential hypertension, pulse pressure, and systolic blood pressure response to postural challenge. Because of the importance of NEDD4L to Na+ balance, many of these studies have proposed that mutations in NEDD4L may be responsible for these blood pressure phenotypes. To test this hypothesis, we fine-mapped the NEDD4L region in 2 families with orthostatic hypotension, which we previously reported to be linked to human chromosome 18q21 but failed to implicate NEDD4L in these families. We also typed multiple NEDD4L single-nucleotide polymorphisms (SNPs) in a collection of US whites, Greek whites, and African-Americans individuals with essential hypertension. A significant association between several SNPs and hypertension was observed in all 3 populations. One of the SNPs associated in African Americans is known to result in premature truncation of the NEDD4L protein. Thus, genetic variation in NEDD4L may play a role in the development or progression of some forms of abnormal blood pressure.

Black or African American↗

PubMed2005

Heritability and a genome-wide linkage scan for arterial stiffness, wave reflection, and mean arterial pressure: the Framingham Heart Study.

BACKGROUND: Arterial stiffness and mean arterial pressure variably contribute to systolic hypertension and increased cardiovascular risk. However, few prior community-based studies have evaluated the genetics of arterial stiffness and separate mean and pulsatile components of blood pressure. METHODS AND RESULTS: Using arterial tonometry, we evaluated heritability and linkage of forward and reflected wave amplitude, mean arterial pressure, and carotid-femoral pulse wave velocity (CFPWV) in 1480 participants representing 817 pedigrees in the Framingham Study offspring cohort. In 204 families with tonometry data, a genome-wide scan was performed with microsatellite markers that covered the genome at 10-cM intervals. Heritability estimates were moderate for reflected wave amplitude (h2=0.48), forward wave amplitude (h2=0.21), CFPWV (h2=0.40), and mean arterial pressure (h2=0.33). Variance components linkage analysis identified 2 regions of linkage for reflected wave amplitude: chromosome 4 at 181 cM (logarithm of odds [LOD]=4.93, permuted P=0.002) and chromosome 8 at 33 cM (LOD=3.27, permuted P=0.058). There was 1 region of linkage for forward wave amplitude on chromosome 7 at 174 cM (LOD=2.88, permuted P=0.017). There were several regions of suggestive linkage for CFPWV: chromosome 2 at 94 cM (LOD=2.46), chromosome 7 at 29 cM (LOD=2.50), chromosome 13 at 108 cm (LOD=2.10), and chromosome 15 at 108 cM (LOD=2.48). There was 1 region of suggestive linkage for mean arterial pressure on chromosome 1 at 192 cM (LOD=2.18). CONCLUSIONS: Arterial stiffness measures and mean and pulsatile components of blood pressure are heritable and appear to have genetic determinants that may be linked to separate genetic loci in humans.

Aged↗

PubMed2005

Expectation maximization algorithm based haplotype relative risk (EM-HRR): test of linkage disequilibrium using incomplete case-parents trios.

The Haplotype Relative Risk (HRR) was first proposed [Falk et al., Ann Hum Genet 1987] to test for Linkage Disequilibrium (LD) between a marker and a putative disease locus using case-parent trios. Spurious association does not appear in such family-based studies under population admixture. In this paper, we extend the HRR to accommodate incomplete trios via the Expectation-Maximization (EM) algorithm [Dempster et al., J R Stat Soc Ser B, 1977]. In addition to triads and dyads (parent-offspring pair), the EM-HRR easily incorporates individuals with no parental genotype information available, which is excluded from the one parent Transmission/Disequilibrium Test (1-TDT) [Sun et al., Am J Epidemiol 1999]. Due to the data structure of EM-HRR, transmitted alleles are always available regardless of the number of missing parental genotypes. As a result of having a larger sample size, computer simulations reveal that the EM-HRR is more powerful in detecting LD than the 1-TDT in a population under Hardy-Weinberg Equilibirum (HWE). If admixture is not extreme, the EM-HRR remains more powerful. When a large degree of admixture exists, the EM-HRR performs better the 1-TDT when the association is strong, though not as well when the association is weak. We illustrate the proposed method with an application to the Framingham Heart Study.

Algorithms↗

PubMed2005

Polymorphisms in the promoter region of catalase gene and essential hypertension.

Genetic variations that predispose individuals to complex disorders, such as essential hypertension, may be found in gene coding regions, intronic regions or in gene promoter regions. Most studies have focused on gene variations that result in amino acid substitutions because they result in different isoforms of the protein, presumably resulting in differences in protein properties. Less attention has been placed on the role of intronic or promoter mutations. In this report, we examined two single nucleotide polymorphisms (SNPs) in the catalase (CAT) gene prompter region in a cohort of hypertensive Caucasians and African Americans with a Mass Spec based Homogenous MassEXTEND assay. We found an association when a specific combination of the two promoter SNPs was examined in Caucasians. No association was observed in African Americans. Our data suggest that genetic variations in the promoter region of catalase gene influence the susceptibility to essential hypertension. In addition, the genetic factors that contribute to hypertension maybe different between ethnic groups.

Aged↗

PubMed2004

Genome-wide scan for pulse pressure in the National Heart, Lung and Blood Institute's Framingham Heart Study.

The objective of this study was to assess heritability and identify chromosomal regions showing evidence of linkage to pulse pressure (PP), a simple indicator of proximal conduit vessel stiffness. Blood pressure data were analyzed for 8478 members of the National Heart, Lung and Blood Institute's (NHLBI) Framingham Heart Study. Long-term PP was defined using 2-stage analysis. First, the difference between systolic and diastolic blood pressure was averaged over all qualifying clinic examinations. In the second stage, mean PP was adjusted for mean age, time period of examination, and body mass index by regression analysis. PP values were available for 6421 individuals in 1593 families for heritability estimation and for 2492 individuals in 330 families for linkage analysis. Microsatellite markers covering the genome at 10 cM intervals were typed by the NHLBI Mammalian Genotyping Service; genome scan data were available on 1585 individuals with PP data. Heritability estimates of long-term PP accounting for hypertension treatment and for ignoring treatment were 0.52 and 0.51, respectively. Variance component linkage analysis identified several locations with suggestive evidence of linkage: chromosome 15 at 122 cM (logarithm of odds [LOD]=2.94), chromosome 7 at 71 cM (LOD=2.42), chromosome 5 at 53 cM (LOD=2.03), and chromosome 10 at 81 cM (LOD=1.83) for PP accounting for treatment. LOD scores were slightly lower when ignoring treatment, with the exception of a peak on chromosome 10 at 81 cM (LOD=2.58). In conclusion, we have demonstrated a substantial genetic component to PP and have identified 4 chromosomal regions that may harbor genes influencing vascular stiffness.

Blood Pressure↗

PubMed2003

Genetic analyses of longitudinal phenotype data: a comparison of univariate methods and a multivariate approach.

BACKGROUND: We explored three approaches to heritability and linkage analyses of longitudinal total cholesterol levels (CHOL) in the Genetic Analysis Workshop 13 simulated data without knowing the answers. The first two were univariate approaches and used 1) baseline measure at exam one or 2) summary measures such as mean and slope from multiple exams. The third method was a multivariate approach that directly models multiple measurements on a subject. A variance components model (SOLAR) was employed in the univariate approaches. A mixed regression model with polynomials was employed in the multivariate approach and implemented in SAS/IML. RESULTS: Using the baseline measure at exam 1, we detected all baseline or slope genes contributing a substantial amount (0.08) of variance (LOD > 3). Compared to the baseline measure, the mean measures yielded slightly higher LOD at the slope genes, and a lower LOD at the baseline genes. The slope measure produced a somewhat lower LOD for the slope gene than did the mean measure. Descriptive information on the pattern of changes in gene effects with age was estimated for three linked loci by the third approach. CONCLUSION: We found simple univariate methods may be effective to detect genes affecting longitudinal phenotypes but may not fully reveal temporal trends in gene effects. The relative efficiency of the univariate methods to detect genes depends heavily on the underlying model. Compared with the univariate approaches, the multivariate approach provided more information on temporal trends in gene effects at the cost of more complicated modelling and more intense computations.

Adult↗

PubMed2003

Linkage and association with pulmonary function measures on chromosome 6q27 in the Framingham Heart Study.

Spirometric measures of pulmonary function have been shown to be highly heritable and evidence for major genes influencing forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) have been reported. A genome scan of pulmonary traits in the Framingham Heart Study identified a region on chromosome 6qter with evidence for linkage to FEV1 and the FEV1/FVC ratio. For this study, additional markers were genotyped in the region to refine the location of linkage and test for association. Variance component linkage analysis was performed using GENEHUNTER, and family-based association tests were performed using FBAT. The chromosome 6 telomeric region provided significant evidence of linkage with the additional markers, resulting in a maximum multipoint LOD score of 5.0 for FEV1 at 184.5 cM. LOD scores for FVC and the FEV1/FVC ratio were also above 1.0 in this region. Evidence for association with FEV1 and FVC was observed with D6S281 at 190 cM. The strongest effect was seen with the 224 allele, which was associated with higher levels of FEV1 and FVC in allele carriers compared with those carrying other alleles. This study supports the presence of a gene influencing pulmonary function on the q-terminus of chromosome 6 in the region of 184 cM (D6S503) to 190 cM (D6S281).

Adult↗

PubMed2003

Genetic variants of WNK4 in whites and African Americans with hypertension.

Human chromosome 17q has been implicated to contain a gene that influences hypertension susceptibility. This region contains the WNK4 gene that causes the mendelian disorder pseudohypoaldosteronism type II, characterized by high potassium levels and hypertension. The goal of this study was to identify genetic variants in all exons of WNK4 in hypertensive individuals and to examine the association of these variants with essential hypertension. Single-nucleotide polymorphims (SNPs) were identified by sequencing the entire coding region in 32 whites and 32 African Americans with hypertension. A single SNP in whites and 8 SNPs in African Americans were genotyped in a larger cohort of whites (165 hypertensives; 91 normotensives) and African Americans (120 hypertensives; 98 normotensives). The frequency of the rare allele differed significantly between hypertensive whites (13.0%) and normotensive whites (7.1%, P=0.040) for the single intronic SNP (bp 1 156 666). This difference remained significant after adjusting for body mass index and sex (P=0.035). Genotypic frequencies differed significantly between hypertensive and normotensive individuals when a dominant model either with (P=0.027) or without (P=0.028) covariate adjustment was assumed. The odds ratio for hypertension was 2.28 for AA or AG individuals vs those with the GG genotype (95% confidence interval, 1.09 to 4.75). No significant differences in allelic or genotypic frequencies were observed in African Americans for any SNPs. The finding in whites is consistent with the hypothesis that polymorphisms in WNK4 influence the risk of hypertension. However, because the associated SNP does not appear to be a functional variant and the limitations of case/control association studies, confirmation of these results in additional cohorts is warranted.

Africa↗

PubMed2003

A genome-wide scan of pulmonary function measures in the National Heart, Lung, and Blood Institute Family Heart Study.

Spirometric measures of pulmonary function exhibited high heritability in the National Heart, Lung, and Blood Institute Family Heart Study. A genome scan of FEV1, FVC, and the ratio of FEV1/FVC was performed to identify chromosomal regions influencing these measures. The pulmonary traits were adjusted through multiple linear regression techniques for the effects of age, age2, body mass index, height, smoking status, and pack-years of smoking. The distribution of FEV1/FVC was transformed to account for nonnormality, and standardized residuals were used as the quantitative trait for variance component linkage analysis in GENEHUNTER (Whitehead Institute, Cambridge, MA). The genome scan identified regions on chromosomes 4 and 18 with logarithm of the odds favoring linkage (LOD) scores above 2.5, and these two chromosomes were further evaluated by incorporating additional marker genotyping. The FEV1/FVC ratio was linked to chromosome 4 around 28 centimorgans (cM; D4S1511) with a LOD score of 3.5, and the transformed ratio was linked to the same region with a LOD of 2.0. FEV1 and FVC were suggestively linked to regions on chromosome 18 with multipoint LOD scores of 2.4 for FEV1 and 1.5 for FVC at 31 cM (D18S843) and a LOD of 2.9 for FVC at 79 cM (D18S858).

Chromosomes, Human, Pair 18↗

PubMed2003

Genomewide linkage analysis to presbycusis in the Framingham Heart Study.

OBJECTIVE: To identify chromosomal regions that show evidence of linkage to age-associated hearing impairment (presbycusis) in humans. DESIGN: We evaluated the genetic linkage between quantitative measures from audiometric examinations and markers from a genomewide scan in a population-based sample ascertained without respect to hearing status. PARTICIPANTS: Audiometric examinations were conducted on 2263 original cohort members and 2217 offspring cohort members of the National Heart, Lung, and Blood Institute's Framingham Heart Study. Of these, 1789 individuals were members of 328 extended pedigrees used for linkage analysis. The outcome traits for linkage analysis were pure-tone average at medium (0.5, 1.0, and 2.0 kHz) and low (0.25, 0.5, and 1.0 kHz) frequencies adjusted for cohort, sex, age, age squared, and age cubed. RESULTS: We found heritability (proportion of variance due to genes) of age-adjusted pure-tone average at medium and low frequencies to be 0.38 and 0.31, respectively. Genomewide linkage analysis identified several locations with suggestive evidence of linkage. Of particular interest are the regions 11p (maximum multipoint logarithm of odds [MLOD], 1.57), 11q13.5 (MLOD, 2.10), and 14q (MLOD, 1.55), which overlap with genes known to cause congenital deafness. CONCLUSIONS: There is evidence that genetic and environmental factors contribute to hearing loss in the mature human population. Several of the chromosomal locations identified overlap with loci known to cause congenital hearing loss. Further studies are needed to determine whether the same genes cause presbycusis and congenital hearing loss.

Aged↗

PubMed2003

Association of polymorphisms in the promoter region of the PNMT gene with essential hypertension in African Americans but not in whites.

BACKGROUND: Several studies have indicated that a region on human chromosome 17 may influence blood pressure. Our group reported positive linkage for hypertension to the region on human chromosome 17, between D17S1814 and D17S800 in white sibling pairs. In this study, we further investigated this result by examining the phenylethanolamine N-methyltransferase (PNMT) gene, which is located at 17q21 within the region where we found linkage. METHODS: A case/control association study was conducted to evaluate the relationship between genetic variants of the PNMT gene and risk for essential hypertension. Two single nucleotide polymorphisms (SNPs) in the promoter region of the gene were genotyped, PNMT-148 and PNMT-353, in three ethnic samples: African American (117 hypertensive, 96 normotensive), American white (91 hypertensive, 80 normotensive), and Greek white (99 hypertensive, 90 normotensive), using the homogeneous mass extend reaction (Sequenom) and RFLP for genotyping. RESULTS: A significant difference in allelic frequency of SNP-353 between hypertensives (38.02%) and normotensives (27.35%) in African Americans (P =.019) was found; however, no significant differences were observed for this SNP for the other ethnic groups. No association was found with SNP PNMT-148 in any of the ethnic groups. Frequencies of haplotypes based on the two SNPs were also compared between hypertensive and normotensive individuals. No significant difference was found in estimated haplotype frequencies between hypertensive and control subjects in the three ethnic groups. CONCLUSIONS: These results suggest that genetic variants of PNMT may play a role in the development of essential hypertension.

Black or African American↗

PubMed2002

PARK3 influences age at onset in Parkinson disease: a genome scan in the GenePD study.

Parkinson disease (PD) is a late-onset neurodegenerative disorder. The mean age at onset is 61 years, but the disease can range from juvenile cases to cases in the 8th or 9th decade of life. The parkin gene on chromosome 6q and loci on chromosome 1p35-36 and 1p36 are responsible for some cases of autosomal recessive early-onset parkinsonism, but they do not appear to influence susceptibility or variability of age at onset for idiopathic PD. We have performed a genomewide linkage analysis using variance-component methodology to identify genes influencing age at onset of PD in a population of affected relatives (mainly affected sibling pairs) participating in the GenePD study. Four chromosomal loci showed suggestive evidence of linkage: chromosome 2p (maximum multipoint LOD [MaxLOD] = 2.08), chromosome 9q (MaxLOD = 2.00), chromosome 20 (MaxLOD = 1.82), and chromosome 21 (MaxLOD = 2.21). The 2p and 9q locations that we report here have previously been reported as loci influencing PD affection status. Association between PD age at onset and allele 174 of marker D2S1394, located on 2p13, was observed in the GenePD sample (P=.02). This 174 allele is common to the PD haplotype observed in two families that show linkage to PARK3 and have autosomal dominant PD, which suggests that this allele may be in linkage disequilibrium with a mutation influencing PD susceptibility or age at onset of PD.

Adult↗

PubMed2002

Is DFNA5 a susceptibility gene for age-related hearing impairment?

A mutation in DFNA5 leads to a type of hearing loss that closely resembles the frequently observed age-related hearing impairment (ARHI). The hearing loss is sensorineural, progressive and starts at the high frequencies. As DFNA5 was considered an excellent candidate ARHI susceptibility gene, we performed linkage analysis to a quantitive measure of high frequency hearing loss. However, no significant linkage between ARHI and microsatellite markers from the DFNA5 region could be detected. Subsequently, the DFNA5 coding region was analysed for single nucleotide polymorphisms (SNPs). Two SNPs leading to amino-acid substitutions (P142H and V207M) were selected for further analysis. Using these SNPs, an association study based on a collection of random individuals, and a case-control association study were performed. No significant differences in genotypes between good hearing and hearing impaired individuals could be detected in either study design. We conclude that there exists no strong association between DFNA5 and ARHI.

Aging↗