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J M Vance

Publications and source records attributed to J M Vance.

96 records · Page 6Linked to original sources
PubMed1981

Carrier detection in Sanfilippo syndrome type B: report of six families.

Serum samples from 175 individuals in six Sanfilippo syndrome type B (SFB) families and 360 White controls were assayed for serum alpha-N-acetyl-D-glucosaminidase (NAG) activity. Only minimal overlap was observed between the controls' NAG activity distribution and that of the 12 obligate heterozygotes. The distribution of NAG activity was log transformed to reduce skewness, and segregation of family members with a prior risk of being a SFB carrier was well within expected limits. However, in one consanguineous family the NAG activity of both parents of one SFB obligate heterozygote was within the normal range for NAG activity. Plausible explanations for this finding are discussed. Additionally, the serum NAG activity of one control and her mother were found to lie within one standard deviation of the obligate heterozygote mean. These individuals are most probably carriers for SFB.

Acetylglucosaminidase↗
PubMed1980

Evidence of genetic variation for alpha-N-acetyl-D-glucosaminidase in black and white populations: a new polymorphism.

Serum and/or plasma samples from 360 Whites and 126 Blacks were assayed for activity of the lysosomal hydrolase alpha-N-acetyl-D-glucosaminidase (NAG). The samples from the Blacks had an increased mean (0.50 nm/ml/min) and standard deviation (0.30 nm/ml/min) compared to those from the Whites (0.29 nm/ml/min and 0.10 nm/ml/min, respectively). After loge transformation and admixture analysis, it was possible to demonstrate the presence of 3 distributions of NAG activity in Blacks and at least 2 in Whites. Segregation analysis of the NAG activity of 29 White half-sib twin families indicated that a genetic model for the inheritance of NAG activity provided a better fit (P less than 0.01) with the data than the "environmental" model. Thus, the study suggests the presence of a genetic polymorphism for NAG activity in Black and White populations. The presence of alleles for high and low NAG activity in the normal population could lead to incorrect interpretation of serum carrier tests for Sanfilippo syndrome, type B.

Acetylglucosaminidase↗
PubMedDate not supplied

Exon 10b of the NF1 gene represents a mutational hotspot and harbors a recurrent missense mutation Y489C associated with aberrant splicing.

PURPOSE: To analyze the spectrum and frequency of NF1 mutations in exon 10b. METHODS: Mutation and sequence analysis was performed at the DNA and cDNA level. RESULTS: We identified nine exon 10b mutations in 232 unrelated patients. Some mutations were recurrent (Y489C and L508P), others were unique (1465-1466insC and IVS10b+2delTAAG). Surprisingly, at the RNA level, Y489C causes skipping of the last 62 nucleotides of exon 10b. Another recurrent mutation, L508P, is undetectable by the Protein Truncation Test. CONCLUSION: As exon 10b shows the highest mutation rate yet found in any of the 60 NF1 exons, it should be implemented with priority in mutation analysis.

Adolescent↗
PubMedDate not supplied

Exclusion of identified LGMD1 loci from four dominant limb-girdle muscular dystrophy families.

The limb-girdle muscular dystrophies are a clinically and genetically heterogeneous group of disorders. Recent linkage analyses and positional cloning studies have identified numerous loci responsible for the recessive and dominant forms, underscoring the inherent heterogeneity. In this report, we investigate four large autosomal dominant limb-girdle pedigrees and exclude these pedigrees from linkage to these loci. In addition, there is no evidence for linkage to any of the seven recessive LGMD loci.

Chromosomes, Human↗
PubMedDate not supplied

Evidence for genetic heterogeneity supports clinical differences in congenital myasthenic syndromes.

Congenital myasthenic syndromes (CMS) define a diverse group of disorders, all of which compromise neuromuscular transmission. Symptoms can be present at birth or appear during childhood, and can range in severity. Both autosomal dominant and recessive forms exist, and a number of clinical subtypes have been described. The cause of many cases of CMS has been traced to mutations in the genes for the acetylcholine receptor (AChR) subunits, previously mapped to chromosomes 2 and 17. Recently, an additional form of CMS known as familial infantile myasthenia (FIM) was linked to chromosome 17p. The gene for FIM has not yet been identified. We examined the DNA from 5 families of Iranian Jewish origin (6 affected individuals) who have been diagnosed with a phenotypically unique form of CMS. Four of the families are consanguinous, and all families originate from the same geographical region, thus it is highly likely that they would carry the same ancestral CMS mutation. We examined these families for linkage to the regions on chromosomes 2 and 17 containing the AChR subunit genes, and to the region on 17p to which FIM was localized. Our data excludes linkage to these regions, suggesting that the clinical differences seen among patients with CMS correlate with locus heterogeneity, and that a defect in a different gene is responsible for the CMS in these patients.

Female↗