A 4-Mb deletion in the region Xq27.3-q28 is associated with non-random inactivation of the non-mutant X chromosome
- Hospital for Sick Children, Toronto (Canada); and others
A girl with severe Hunter disease was found to have a submicroscopic deletion distrupting the IDS locus in the region Xq27.3-q28 together with non-random inactivation of the non-mutant X chromosome. Southern analysis of DNA from the parents and from hamster-patient somatic cell hybrids containing only the mutant X chromosome revealed that the deletion represented a de novo mutation involving the paternal X chromosome. Methylation-sensitive RFLP analysis of DNA from maternal fibroblasts and lymphocytes showed methylation patterns consistent with random X-inactivation, indicating that the non-random X-inactivation in the patient was not inherited and was likely a direct result of the Xq27.3-q28 deletion. A 15 kb EcoRI junction fragment, identified in patient DNA using IDS cDNA probes, was cloned from a size-selected patient DNA library. Clones containing the deletion junction were restriction mapped and fragments were subcloned and used to isolate normal sequence on either side of the deletion from normal X chromosome libraries. Comparison of the sequences from normal and mutant X chromosome clones straddling the deletion breakpoint showed that the mutation had occurred by recombination between Alu repeats. Screening of YAC contigs containing normal X chromosome sequence from the region of the mutation, using probes from either side of the deletion breakpoint, showed that the deletion was approximately 4 Mb in size. Probing of mutant DNA with 16 STSs distributed throughout the region of the deletion confirmed that the mutation is a simple deletion with no complex rearrangements of islands of retained DNA. A search for sequences at Xq27.3-q28 involved in X chromosome inactivation is in progress.
- OSTI ID:
- 134193
- Report Number(s):
- CONF-941009-; ISSN 0002-9297; TRN: 95:005313-0929
- 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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