Molecular and cytogenetic analysis of familial Xp deletions
- Case Western Reserve, Cleveland, OH (United States); and others
Deletions involving the short arm of the X chromosome (del(Xp)) manifest phenotypes ranging from Turner syndrome to isolated short stature to normal. We have studied five familial cases of del(Xp), four with transmission over two generations and one over four generations, utilizing both high resolution chromosome banding and FISH with cosmid and YAC probes spanning the short arm of the X chromosome. Four of the families were ascertained because of short stature while the remaining family demonstrates normal stature and was ascertained through prenatal diagnosis. Consistent with existing data for a growth gene located within Xp22.33, the more terminal breakpoints in the female with normal stature is distal to CSF2RA. A correlation between genotype and phenotype amongst the families may reveal that this case is representative of an interstitial deletion and the other four cases have breakpoints distal to the growth gene locus possibly within the subtelomeric region of the chromosome. The proximal breakpoints are heterogenous; however, three of the families with short stature share a common proximal breakpoint which is located between two YAC probes 2-3 Mb apart in Xp22.12. The proximal break in the phenotypically normal female is in Xp11.4. Late replication studies in addition to methylation assays of the FMR1 locus reveal non-random X inactivation in these cases. This study shows the presence of a breakpoint distal to the CSF2RA locus in the family demonstrating normal stature confirming the location of a growth gene distal to this locus and within Xp22.33. The shared proximal breakpoint between the three families suggests a {open_quotes}hot spot{close_quotes} for chromatin breakage. The proximal breakpoint, Xp11.4, in the normal female patient excludes this region as an etiologic factor in Turner syndrome. Work is in progress using additional probes to further elucidate both the proximal and distal breakpoints.
- OSTI ID:
- 133779
- Report Number(s):
- CONF-941009--
- Journal Information:
- American Journal of Human Genetics, Journal Name: American Journal of Human Genetics Journal Issue: Suppl.3 Vol. 55; ISSN AJHGAG; ISSN 0002-9297
- Country of Publication:
- United States
- Language:
- English
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