X染色体短腕中部に想定される精神遅滞責任遺伝子の欠失マッピングとX染色体不活化解析

概要

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We report the deletion mapping and X-inactivation analysis of a gene for X-linked non-specific mental retardation (MRX) in the middle region of Xp, in three families with small Xp interstitial deletions. Mental evaluation by clinical assessment and/or IQ/DQ tests indicated that, irrespective of sex, members in families 1 and 3 had mental retardation (MR), whereas those in family 2 were free from MR. Polymerase chain reaction analysis of 23 loci in the middle part of Xp showed that the male patients of all three families were missing regions between DXS7182 and DXS1022, between DXS319 and DXS1022, and between DXS7182 and DXS6678, respectively. Fluorescence in situ hybridization (FISH) analysis of DAX-1 and DXZ1 revealed that the females of families 1 and 3 were heterozygous for the Xp deletion. X-inactivation analysis of the methylation status of the AR or the HPRT gene showed that the female heterozygotes had random X-inactivation. These results suggest that an MRX gene that is subject to X-inactivation is present in a roughly 4-Mb region between DXS7182 and DAX-1, and that reduced expression of the normal MRX gene caused by random X-inactivation results in MR in female heterozygotes.
東京女子医科大学の論文
2000-03-25