Increased disomic homozygosity in the telomeric region of chromosome 21 among Down Syndrome individuals with duodenal atresia
- Emory Univ., Altanta, GA (United States)
Although duodenal atresia (DA) is present in only 4-7% of all Down Syndrome (DS) individuals, 30-50% of all congenital duodenal atresias occur in the DS population, suggesting the presence of gene(s) on chromosome 21 that play an important role in intestinal development. We recently proposed a chromosome 21 gene dosage model to explain the phenotypic variance seen among DS individuals and presented a strategy to map genes involved in these phenotypic traits. We suggest that {open_quote}hyper-dosage{close_quote} resulting from normal allelic differences explains the phenotypic variation. A proportion of trisomic genotypes would exceed some activity threshold and express the trait. In affected individuals, this increase in expression is due to the presence of two identical copies of {open_quote}susceptibility{close_quote} allele, inherited from a heterozygous parent of origin. Individuals with trisomy 21 and a specific phenotypic defect should exhibit increased levels of disomic homozygosity in the region containing the gene involved in the defect`s etiology. These data can be used to map these genes. Using this approach, we have examined markers along the long arm of chromosome 21 among DS individuals with DA and determined the degree of disomic homozygosity at each marker. This frequency was compared to the level of disomic homozygosity among our entire DS study population consisting of approximately 380 DS families to test for linkage between DA and each marker. Preliminary analysis of 13 DS cases with DA indicates an increase in disomic homozygosity along the distal region of the chromosome, from HMG14 to D21S171, the most telomeric marker analyzed. An additional 15 cases are currently being analyzed to confirm and better define this candidate region.
- OSTI ID:
- 134054
- Report Number(s):
- CONF-941009-; ISSN 0002-9297; TRN: 95:005313-0790
- Journal Information:
- American Journal of Human Genetics, Vol. 55, Issue Suppl.3; Conference: 44. annual meeting of the American Society of Human Genetics, Montreal (Canada), 18-22 Oct 1994; Other Information: PBD: Sep 1994
- Country of Publication:
- United States
- Language:
- English
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