Connexin26 mutations associated with the most common form of non-syndromic neurosensory autosomal recessive deafness (DFNB1) in Mediterraneans

Non-syndromic neurosensory autosomal recessive deafness (NSRD) is the most common form of genetic hearing loss. Previous studies defined at least 15 human NSRD loci. Recently we demonstrated that DFNB1, located on the long arm of chromosome 13, accounts for approximately 80% of cases in the Mediterranean area. Further analysis with additional markers now identifies several recombinants which narrow the candidate region to approximately 5 cM, encompassed by markers D13S141 and D13S232 and including several ESTs and candidate genes, including the connexin26 (GJB2) gene. Analysis of PCR products from our affected patients' DNA shows two frameshift mutations in the connexin26 gene. Deletion of a G within a stretch of six Gs at position 35 of the GJB2 cDNA (mutation 35delG) leads to premature chain termination and is present in 63% of NSRD chromosomes, demonstrating linkage to chromosome 13. Deletion of a T at position 167 of GJB2 (mutation 167delT), also resulting in premature chain termination, was detected in another patient. Four neutral sequence polymorphisms were also identified. These findings are in agreement with a recent study showing that mutations in the connexin26 gene are associated with genetic forms of deafness in three Pakistani families and that GJB2 is DFNB1. Connexin26 is a member of a large family of proteins involved in formation of gap junctions, which are involved in electrical synapses and the direct transfer of small molecules and ionic currents between neighboring cells. The identification of GJB2 as the DFNB1 gene should provide a better understanding of the biology of normal and abnormal hearing, help form the basis for diagnosis and may facilitate development of strategies for treatment of this common genetic disorder.     

An alpha-tectorin gene defect causes a newly identified autosomal recessive form of sensorineural pre-lingual non-syndromic deafness, DFNB21

In our efforts to identify new loci responsible for non-syndromic autosomal recessive forms of deafness, DFNB loci, we have pursued the analysis of large consanguineous affected families living in geographically isolated areas. Here, we report on the study of a Lebanese family comprising nine members presenting with a pre-lingual severe to profound sensorineural isolated form of deafness. Linkage analysis led to the characterization of a new locus, DFNB21, which was assigned to chromosome 11q23-25. Already mapped to this chromosomal region was TECTA. This gene encodes alpha-tectorin, a 2155 amino acid protein which is a component of the tectorial membrane. This gene recently has been shown to be responsible for a dominant form of deafness, DFNA8/12. Sequence analysis of the TECTA gene in the DFNB21-affected family revealed a G to A transition in the donor splice site (GT) of intron 9, predicted to lead to a truncated protein of 971 amino acids. This establishes that alpha-tectorin mutations can be responsible for both dominant and recessive forms of deafness. Comparison of the phenotype of the DFNB21 heterozygous carriers with that of DFNA8/12-affected individuals supports the hypothesis that the TECTA mutations which cause the dominant form of deafness have a dominant-negative effect. The present results provide genetic evidence for alpha-tectorin forming homo- or heteromeric structures.     

Linkage of congenital, recessive deafness (DFNB4) to chromosome 7q31 and evidence for genetic heterogeneity in the Middle Eastern Druze population

Clinically significant hearing loss affects 1 in 1000 infants and it is estimated that at least 50% of these cases are due to a genetic cause. Some forms of inherited deafness are syndromic and affected individuals have a specific pattern of additional features while in other families the deafness is non-syndromic and there is no other recognizable phenotype. Analysis of several large families with syndromic and non-syndromic forms of deafness have been used in genetic linkage analysis to identify genes or gene locations that cause deafness. Here, we describe a large Middle-Eastern Druze family with recessive non-syndromic deafness and demonstrate linkage between deafness in this family and human chromosome 7q31 with a lod score exceeding 5.5. This is the first evidence for a gene at this location that causes deafness. In addition, we found that deafness in three other Druze pedigrees, one related to the linked family, is not linked to this chromosomal location. This suggests that there are multiple nonallelic mutations for deafness in this genetic isolate.     

Association of unconventional myosin MYO15 mutations with human nonsyndromic deafness DFNB3

DFNB3, a locus for nonsyndromic sensorineural recessive deafness, maps to a 3-centimorgan interval on human chromosome 17p11.2, a region that shows conserved synteny with mouse shaker-2. A human unconventional myosin gene, MYO15, was identified by combining functional and positional cloning approaches in searching for shaker-2 and DFNB3. MYO15 has at least 50 exons spanning 36 kilobases. Sequence analyses of these exons in affected individuals from three unrelated DFNB3 families revealed two missense mutations and one nonsense mutation that cosegregated with congenital recessive deafness.     

Dominant inheritance in two families with familial Mediterranean fever (FMF)

Familial Mediterranean fever (FMF) is an autosomal-recessive disease which affects almost exclusively people of Mediterranean and Middle Eastern origin. We examined the possibility of a dominant inheritance of FMF among our 3,000 patients in Israel. Two hundred forty FMF patients were members of 77 families in which the disease affected more than one generation. In 75 of these families the occurrence of FMF in more than one generation was found to be consistent with a recessive mode of inheritance due to a high gene frequency (q) and consanguinity among parents of the patients. In 2 families, one of Ashkenazi and the other of Georgian Iraqi origin, in which FMF occurred in 4 consecutive generations, the mode of inheritance could be explained only by autosomal-dominant inheritance.     

Genetic heterogeneity and penetrance analysis of the BRCA1 and BRCA2 genes in breast cancer families. The Breast Cancer Linkage Consortium

The contribution of BRCA1 and BRCA2 to inherited breast cancer was assessed by linkage and mutation analysis in 237 families, each with at least four cases of breast cancer, collected by the Breast Cancer Linkage Consortium. Families were included without regard to the occurrence of ovarian or other cancers. Overall, disease was linked to BRCA1 in an estimated 52% of families, to BRCA2 in 32% of families, and to neither gene in 16% (95% confidence interval [CI] 6%-28%), suggesting other predisposition genes. The majority (81%) of the breast-ovarian cancer families were due to BRCA1, with most others (14%) due to BRCA2. Conversely, the majority of families with male and female breast cancer were due to BRCA2 (76%). The largest proportion (67%) of families due to other genes was found in families with four or five cases of female breast cancer only. These estimates were not substantially affected either by changing the assumed penetrance model for BRCA1 or by including or excluding BRCA1 mutation data. Among those families with disease due to BRCA1 that were tested by one of the standard screening methods, mutations were detected in the coding sequence or splice sites in an estimated 63% (95% CI 51%-77%). The estimated sensitivity was identical for direct sequencing and other techniques. The penetrance of BRCA2 was estimated by maximizing the LOD score in BRCA2-mutation families, over all possible penetrance functions. The estimated cumulative risk of breast cancer reached 28% (95% CI 9%-44%) by age 50 years and 84% (95% CI 43%-95%) by age 70 years. The corresponding ovarian cancer risks were 0.4% (95% CI 0%-1%) by age 50 years and 27% (95% CI 0%-47%) by age 70 years. The lifetime risk of breast cancer appears similar to the risk in BRCA1 carriers, but there was some suggestion of a lower risk in BRCA2 carriers <50 years of age.     

Linkage relationships of the loci of the major histocompatibility complex in families with a recombination in the HLA region

A number of families with an established recombination in the major histocompatibility complex has been investigated for markers known to be coded by genes of this linkage group. The results provide further data on the relative position of the loci for HLA-A, HLA-B, HLA-C, HLA-D, Bf, Chido, Rodgers and PGM3 on chromosome 6. A positive lodscore for linkage between HLA and blood group P was found; lodscores between HLA and nineteen other markers were negative.     

Linkage of antisocial alcoholism to the serotonin 5-HT1B receptor gene in 2 populations

We examined the effects of repeated administration of (S)-alpha-fluoromethylhistidine (FMH), a specific inhibitor of histidine decarboxylase (HDC), on radial maze performance and brain contents of histamine and amino acids in rats. By daily subcutaneous (s.c.) administration of FMH (100 mg/kg), rats showed significant enhancement of a radial maze performance without changes in locomotion. Six days after FMH treatment, the histamine levels both in the cerebral cortex and diencephalon decreased significantly. However, the glutamate and glycine levels significantly increased in the cerebral cortex and hippocampus. These results suggest that FMH enhances the acquisition phase of radial maze study with the increases in glutamate and glycine levels in the cerebral cortex and hippocampus of rats.     

Genetics of vitamin D 1alpha-hydroxylase deficiency in 17 families

Vitamin D-dependent rickets type I (VDDR-I), also known as pseudo-vitamin D-deficiency rickets, appears to result from deficiency of renal vitamin D 1alpha-hydroxylase activity. Prior work has shown that the affected gene lies on 12q13.3. We recently cloned the cDNA and gene for this enzyme, mitochondrial P450c1alpha, and we and others have found mutations in its gene in a few patients. To determine whether all patients with VDDR-I have mutations in P450c1alpha, we have analyzed the P450c1alpha gene in 19 individuals from 17 families representing various ethnic groups. The whole gene was PCR amplified and subjected to direct sequencing; candidate mutations were confirmed by repeat PCR of the relevant exon from genomic DNA from the patients and their parents. Microsatellite haplotyping with the markers D12S90, D12S305, and D12S104 was also done in all families. All patients had P450c1alpha mutations on both alleles. In the French Canadian population, among whom VDDR-I is common, 9 of 10 alleles bore the haplotype 4-7-1 and carried the mutation 958DeltaG. This haplotype and mutation were also seen in two other families and are easily identified because the mutation ablates a TaiI/MaeII site. Six families of widely divergent ethnic backgrounds carried a 7-bp duplication in association with four different microsatellite haplotypes, indicating a mutational hot spot. We found 14 different mutations, including 7 amino acid replacement mutations. When these missense mutations were analyzed by expressing the mutant enzyme in mouse Leydig MA-10 cells and assaying 1alpha-hydroxylase activity, none retained detectable 1alpha-hydroxylase activity. These studies show that most if not all patients with VDDR-I have severe mutations in P450c1alpha, and hence the disease should be referred to as "1alpha-hydroxylase deficiency."     

Mutational analysis of the Jagged 1 gene in Alagille syndrome families

Alagille syndrome (AGS) is an autosomal dominant disease characterized by five major abnormalities in the liver, heart, face, vertebrae and eye. The responsible gene has been recently identified as the human Jagged 1 (JAG1) gene, which encodes a ligand for the Notch receptor. We analyzed the JAG1 gene in eight AGS families, including affected and unaffected individuals, at the genomic DNA level, mainly by single-strand conformational polymorphism (SSCP) and DNA sequencing analysis. Four categories of mutations were identified: (i) four frameshift mutations in exons 9, 22, 24 and 26 were exhibited respectively in affected individuals of four AGS families, which resulted in moving the translational frame of JAG1; (ii) one nonsense mutation, a 1 bp substitution in exon 5 of the EGF-like repeat domain, was detected in two unrelated AGS families, which altered codon 235 from arginine to stop; (iii) one acceptor splice site mutation of exon 5 was revealed in a sporadic patient; and (iv) a 1.3 Mb deletion, which included the entire JAG1 gene, was found in another patient. Our results further demonstrate that AGS is a dominant disease and suggest that the JAG1 gene exerts a fundamental role in regulating genes involved in development.     

Linkage analysis of susceptibility to ozone-induced lung inflammation in inbred mice

Through a survey of all departments of pediatrics, neurology and neuropathology in Germany, we calculated the incidence of all major forms of leukodystrophy. Only diagnoses based on specific biochemical tests in association with typical findings and/or neuroradiologically proven white matter involvement were accepted. In accordance with these strict criteria, 617 cases of leukodystrophy were found (incidence of all forms: app. 2.0/100,000). Minimal incidence was estimated at 0.8/100,000 for adrenoleukodystrophy/adrenomyeloneuropathy (ALD/AMN), 0.6/100,000 for metachromatic leukodystrophy (MLD), and 0.6/100,000 for Krabbe disease. Thus ALD/AMN is apparently underdiagnosed in Germany. A considerable proportion of leukodystrophies could not be classified in spite of adequate diagnostic procedures in experienced centers.     

Linkage assignment of eleven genes to the porcine genome

We report comparative linkage mapping of eleven genes in the swine genome by RFLP analysis. These genes include: Acid phosphatase type 5 (ACP5), Cholecystokinin Type B Receptor (CCKBR), Antibiotic Peptide (FALL39), Insulin-like Growth Factor 1 Receptor (IGF1R), Integrin Alpha M (ITGAM), Integrin Beta 2 (ITGbeta2), Opioid Receptor Mu-1 (OPRM1), Pro-hormone Converter (PC1/3), Retinol Binding Protein 3 (RBP3), Ribosomal DNA (RNR1), and Zona Pellucida Glycoprotein 1 (ZP1). The CCKBR and ITGbeta2 loci define the ends of the linkage groups on Chromosomes (Chro) (SSC) 9p and 13qter, respectively.     

Linkage of proximal myotonic myopathy to chromosome 3q

We performed genetic linkage analysis in nine German proximal myotonic myopathy (PROMM) families using DNA-markers D3S1541 and D3S1589 from the region of the recently discovered gene locus of myotonic dystrophy type 2 (DM2) on chromosome 3q. Two-point analysis supplied an lod score of 5.9. We conclude that a gene causing PROMM is located on chromosome 3q. PROMM and DM2 may be allelic disorders or may be caused by closely linked genes.     

Linkage of circulating eosinophils to markers on chromosome 5q

Although peripheral blood eosinophilia is strongly associated with the risk of developing asthma, genetic determinants of eosinophilia have not been extensively studied. We used sib-pair analysis to assess linkage of circulating eosinophils (as a percent of total white blood cells [WBC]) to nine markers located in chromosome 5q31-33. The study was divided into two phases. Of 246 sib pairs available for the first phase, 35 were classified as low concordant (LC) (both sibs had <= 2% circulating eosinophils), 18 were defined as high concordant (HC) (both sibs had 5% or more circulating eosinophils), and 26 were defined as discordant (one sib had <= 2% and the other sib had 5% or more circulating eosinophils). Significant evidence for linkage among low concordant sib pairs was found for several markers in the region under study, with a peak for marker D5S500 (proportion of alleles shared identical by descent [ibd] = 0.68 +/- 0.05 [mean +/- SE], p = 0.0004). A cross-validating study was done in which an additional 19 sib pairs that were low concordant for circulating eosinophils were studied. Evidence for linkage was also observed in this subset. Results were independent of current wheezing, total serum IgE levels, and other potential confounders. A multipoint analysis done for all low-concordant sib pairs available showed that the maximal logarithm of the odds favoring genetic linkage (LOD) score (2.4, p = 0.0004) was observed in correspondence with marker D5S658. We conclude that a locus or loci may be present in chromosome 5q31-33 that controls for circulating eosinophils as a proportion of total WBC.     

Family interactions in adoptive compared to nonadoptive families.

Despite the large and growing numbers of adoptive families, little research describes interactions in families with adopted adolescents. Yet, adopted adolescents' increased risk for adjustment problems, combined with the association between family interactions and adolescent adjustment in nonadoptive families, raises questions about differences in adoptive and nonadoptive family interactions. We compared observed and self-reported family interactions between 284 adoptive and 208 nonadoptive families and within 123 families with 1 adopted and 1 nonadopted adolescent. Adolescents averaged 14.9 years of age. Comparisons were made using analysis of variance incorporating hierarchical linear methods in SAS PROC MIXED to control family-related correlations in the data. Parents and children reported more conflict in adoptive families when compared with nonadoptive families. Families with 1 adopted and 1 nonadopted adolescent reported more conflict between parents and adopted adolescents. Observed parental behavior was similar across adoptive and nonadoptive children although adopted adolescents were less warm and, in families with 2 adopted children, more conflictual than nonadopted adolescents. These findings suggest a need for further investigation of the association between family interactions and adopted adolescent problem behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Linkage of posterior polymorphous corneal dystrophy to 20q11

Posterior polymorphous dystrophy (PPMD) is an autosomal dominant disorder of the cornea that is clinically recognized by the presence of vesicles on the endothelial surface of the cornea. The corneal endothelium is normally a single layer of cells that lose their mitotic potential after development is complete. In PPMD, the endothelium is often multi-layered and has several other characteristics of an epithelium including the presence of desmosomes, tonofilaments, and microvilli. These abnormal cells retain their ability to divide and extend onto the trabecular meshwork to cause glaucoma in up to 40% of cases. A large family with 21 members affected with PPMD was genotyped with short tandem repeat polymorphisms distributed across the autosomal genome. Linkage was established with markers on the long arm of chromosome 20. The highest observed LOD score was 5.54 (theta = 0) with marker D20S45. Analysis of recombination events in four affected individuals revealed that the disease gene lies within a 30cM interval between markers D20S98 and D20S108.     

A forced-choice technique to evaluate deafness in the hysterical or malingering patient.

Used the 2-alternative forced-choice technique, which has been used to examine hysterical blindness, to assess purported loss of hearing in a 27-yr-old male. The patient was asked to guess which of 2 temporal intervals contained a sound. Significant findings suggest that the patient heard sounds he claimed he was unable to hear. Results are discussed in terms of using the forced-choice technique as a strategy for assessing sensory deficits. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The cost of cancer home care to families

BACKGROUND: For the most part, previous research on costs of cancer care has focused on the formal medical care costs. Research on home care for patients with cancer has emphasized direct care costs (expenditures). Among indirect costs, only loss of income to family members has been studied. However, a major component of indirect costs, the family labor expended to care for the patient with cancer, needs to be included for a more realistic appreciation of home care costs. METHODS: The costs of family labor are estimated by imputing monetary values for the time spent caring for the patient with cancer. The assigned monetary cost either is equated with income losses of the helper in question or is based on a putative market value of the expended labor time. In addition, out-of-pocket expenditures examined in this study cover all cancer care-related expenses for which the patient was not reimbursed by third parties. Data were obtained from a convenience sample of 192 patients with cancer and their families in lower Michigan. RESULTS: When family labor is included in the cost calculations, average cancer home care costs for a 3-month period ($4563) are not much lower than the costs of nursing home care. The substantial variation in home care costs (standard deviation [SD] = $4313) appears to be unrelated to the type of cancer diagnosis, type of treatment, or time since diagnosis but seems to be driven by the functional status of the patient and the family living arrangements. CONCLUSIONS: Outpatient care for patients with cancer coupled with greater reliance on home care appear to be economically attractive because costs to families usually are underestimated.