An Austrian family with nonsyndromic Xlinked mental retardation (MRX) is reported in which the obligatory carrier females are normal, and 5 affected males have mild to moderate mental retardation. Linkage analysis indicated an X pericentromeric localization, with flanking markers DXS989 and DXS1111
X-linked mental retardation: Evidence for a recent mutation in a five-generation family (MRX65) linked to the pericentromeric region
β Scribed by Yntema, Helger G.; van den Helm, Bellinda; Knoers, Nine V.A.M.; Smits, Arie P.T.; van Roosmalen, Tanja; Smeets, Dominique F.C.M.; Mariman, Edwin C.M.; van der Burgt, Ineke; van Bokhoven, Hans; Ropers, Hans-Hilger; Kremer, Hannie; Hamel, Ben C.J.
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 40 KB
- Volume
- 85
- Category
- Article
- ISSN
- 0148-7299
- DOI
- 10.1002/(sici)1096-8628(19990730)85:3<305::aid-ajmg22>3.0.co;2-5
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β¦ Synopsis
We report linkage analysis in a new family with nonspecific X-linked mental retardation, using 27 polymorphic markers covering the entire X-chromosome. We could assign the underlying disease gene, denoted MRX65, to the pericentromeric region, with flanking markers DXS573 in Xp11.3 and DXS990 in Xq21.33. A maximum LOD score of 3.64 was found at markers ALAS2 (Xp11.22) and DXS453 (Xq12) at = 0. Twenty-five of the 58 reported MRX families are linked to a region that is partially overlapping with the region reported here. Extension of the pedigree showed a number of unaffected distant relatives with haplotypes corresponding to the disease locus. Apparently, a new mutation in a female is causative for the disease in the family reported here. Furthermore, we show the importance of combining clinical, cytogenetic, and molecular studies since one of the family members, expected to be affected by the same genetic defect, has a 48,XXXY karyotype. Am. J. Med. Genet.
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