Analysis of human chromosome 21 for a locus conferring susceptibility to Hirschsprung Disease
- Case Western Reserve Univ., Cleveland, OH (United States)
It has been estimated that approximately 5% of patients diagnosed with Hirschsprung disease (HSCR), or aganglionic megacolon, have trisomy 21. Since the incidence of Hirschsprung disease is 1/5000 live births and the incidence of trisomy 21 is approximately 1/1000 live births, the observed occurrence of HSCR in trisomy 21 is fifty times higher than expected. We propose that at least one locus on chromosome 21 predisposes to HSCR. Although at fifty times elevated risk, only 1% of Down Syndrome cases have HSCR. Thus additional genes or genetic events are necessary for HSCR to manifest in patients with trisomy 21. Based on segregation analysis, Badner et al. postulated that recessive genes may be responsible for up to 80% of HSCR. We postulate that at least one such gene is on chromosome 21 and increased homozygosity for common recessive HSCR mutations may be one cause for the elevated risk of HSCR in cases of trisomy 21. To map such a chromosome 21 locus, we are searching for segments of human chromosome 21 which are identical by descent from the parent in whom non-disjunction occurred. These segments will arise either from meiosis I (followed by a crossover between the centromere and the locus) or from meiosis II (followed by no crossovers). Nine nuclear families with a proband diagnosed with HSCR and Down Syndrome have been genotyped for 18 microsatellite markers spanning human chromosome 21q. In all nine cases analyzed thus far, trisomy 21 resulted from maternal non-disjunction at meiosis I. At this point no single IBD region is apparent. Therefore, additional families are being ascertained and additional markers at high density are being genotyped to map the HSCR locus.
- OSTI ID:
- 133988
- Report Number(s):
- CONF-941009-; ISSN 0002-9297; TRN: 95:005313-0723
- 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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