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Biomedical subjects

W E Nance

Publications and source records attributed to W E Nance.

At least 19 recordsLinked to original sources
PubMed2000

Usher syndrome 1D and nonsyndromic autosomal recessive deafness DFNB12 are caused by allelic mutations of the novel cadherin-like gene CDH23.

Genes causing nonsyndromic autosomal recessive deafness (DFNB12) and deafness associated with retinitis pigmentosa and vestibular dysfunction (USH1D) were previously mapped to overlapping regions of chromosome 10q21-q22. Seven highly consanguineous families segregating nonsyndromic autosomal recessive deafness were analyzed to refine the DFNB12 locus. In a single family, a critical region was defined between D10S1694 and D10S1737, approximately 0.55 cM apart. Eighteen candidate genes in the region were sequenced. Mutations in a novel cadherin-like gene, CDH23, were found both in families with DFNB12 and in families with USH1D. Six missense mutations were found in five families with DFNB12, and two nonsense and two frameshift mutations were found in four families with USH1D. A northern blot analysis of CDH23 showed a 9.5-kb transcript expressed primarily in the retina. CDH23 is also expressed in the cochlea, as is demonstrated by polymerase chain reaction amplification from cochlear cDNA.

Alleles↗
PubMed1979

Effects of type of placentation on birthweight and its variability in monozygotic and dizygotic twins.

Birthweight was measured on 188 monochorionic monozygotic, 54 dichorionic monozygotic, 102 like-sexed dizygotic, and 94 unlike-sexed dizygotic liveborn twin pairs. Overall, males were found to be significantly heavier than females. These differences were not significant, however, when birthweights were compared within zygosity/chorion-type categories. Males were also characterized by a slightly greater overall total variance. Comparisons of intrapair variation of monochorionic and dichorionic monozygotic twins revealed significant differences between monochorionic pairs and dichorionic separate pairs and no significant differences between monochorionic pairs and dichorionic fused pairs. The results of this study suggest that placental proximity may have as important an influence on variation in birthweight as does the presence or absence of vascular anastomoses.

Birth Weight↗
PubMed1979

The human X-chromosome and the levels of serum immunoglobulin M.

The serum concentrations of immunoglobulins G, A and M were measured in a sample of 93 pairs of monozygotic twins, their spouses, and their offspring. The hypothesis that the human X-chromosome carries genes which control the levels of immunoglobulin M was tested with three different approaches. Our results indicate that environmental factors are primarily responsible for the observed variation in the levels of IgG and IgA. The variance of IgM seems to be mostly the result of X-linked gene effects, with women having higher IgM levels than men.

Female↗
PubMed1979

Linkage analysis using heterozygote detection in phenylketonuria.

This linkage investigation was undertaken utilizing an improved method for phenylketonuria (PKU) heterozygote detection. This method is based on studies of semi-fasting, noon-time, blood specimens obtained from 85 obligate heterozgotes and 45 controls who were neither pregnant nor on birth control medication. The best separation between heterozygotes and normals was achieved with a discriminant function involving the logarithms of the serum concentrations of phenylalanine, tyrosine and tryptophan. The theoretical overlap area between the distributions of heterozygotes and controls, based on the above function, was between the distributions of heterozygotes and controls, based on the above function, was 3.75%. In 19 obligate heterozygotes and 13 controls who were either pregnant or on birth control medication, the best separation was achieved with a discriminant function involving the logarithms of the serum concentrations of phenylalanine and tyrosine. The theoretical overlap area was 8.23%. These equations identified heterozygotes with sufficient accuracy to permit efficient genetic linkage analysis. We were unable to demonstrate genetic linkage between the PKU locus and 15 common blood, serum, and urinary markers. All but loose linkage (theta greater than 0.3) was excluded for Rh, ABO, Gc, Kidd, and AP. Moderate linkage exclusion (theta less than 0.2) was shown for PGM, Duffy, Hp, MNS, HL--A, and Kell. Close linkage (theta less than 0.1) was excluded for Amy2, 6PGD, P, and ADA. We were unable to find linkage heterogeneity between the Amish and non-Amish populations.

Chromosome Mapping↗
PubMed1978

Systemic membrane defect in the proximal muscular dystrophies.

We studied lymphocyte capping in 61 patients with Duchenne, Becker, limb-girdle, facioscapulohumeral and congenital muscular dystrophies. All showed a markedly diminished percentage of capped cells when compared with 86 normal controls, providing support for previous evidence that an alteration in membrane fluidity may be a common pathogenic feature in several genetically distinct forms of proximal muscular dystrophy. Heterozygous carriers of Duchenne muscular dystrophy showed diminished capping that was indistinguishable from that of afflicted males and was often present even when serum enzyme levels were normal. Studies in 25 families with 16 suspected sporadic cases indicated that no more than four out of 30 afflicted males may represent new mutations. These findings imply that most cases of Duchenne dystrophy might be prevented by a population screening program for carrier females combined with prenatal detection of afflicted males.

Adolescent↗
PubMed1978

Branchio-oto-renal dysplasia and branchio-oto dysplasia: two distinct autosomal dominant disorders.

Three families are presented, one with branchio-oto-renal dysplasia (BOR) and two with branchio-oto dysplasia (BO). The former syndrome is characterized by external ear malformations, cervical fistulae, mixed hearing loss and renal anomalies of varying severity. The latter syndrome differs in that there are no renal anomalies and that the sensorineural component of the hearing loss may be absent. The external ear malformations are quite variable in both syndromes. Evidence is presented which supports the idea that these two syndromes are not phenotypic variants of the same autosomal dominant mutation but distinct disease entities. The BOR syndrome appears to belong to a larger group of hereditary ear dysplasia-renal adysplasia syndromes that must be carefully ruled out in all patients with familial branchial arch malformations as well as in the parents and siblings of infants with "Potter facies" in the presence of auricular malformation and renal adysplasia.

Abnormalities, Multiple↗