Non-specific X-linked mental retardation: Linkage analysis in MRX2 and MRX4 families revisited
- Faculte de Medecine et Centre Hospitalier Regional Universitaire, Strasbourg (France)
- Genethon, Evry (France)
We have previously reported linkage analysis in 3 families with non-specific X-linked mental retardation (XLMR). This used RFLPs and was limited by the relatively low informativeness and density of markers available. We have performed a new linkage analysis using microsatellites (including new Genethon markers) in the two most informative families. In the MRX2 family, a lod score of 2.61 at {theta} = 0.05 had previously been obtained with DXS85 in Xp22.2. We now report a tighter linkage with AFM 135xe7 (DXS989, z = 4.62 at {theta} = 0.00) and established the order DXS85-DXS207-DXS999 (AFM234 yf12)-MRX2, DXS365, DXS1052 (AFM 163yh2), DXS989-DXS1065 (AFM224zf2), DMD 3{prime}. The localization of MRX2 in Xp22.2-p22.1 is thus clearly different from the more distal MRX gene defined by patients with contiguous gene syndromes. In the MRX4 family, a maximum lod score of 2.53 at {theta} = 0.00 had been obtained with DXS159 in Xq13. Our present study did not show recombination from ALAS2 in Xp11.21 to DXS441 in Xq13.3 (z = 3.38 at {theta} = 0.00 for the latter marker) and the closest flanking markers are DXS255 in Xp11.22 and DXYS1 in Xq21.3. Reduced recombination around the centromere prevents precise mapping. The localization of MRX4 overlaps with that of several other MRX families. 26 refs., 3 figs., 2 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 62057
- Journal Information:
- American Journal of Medical Genetics, Journal Name: American Journal of Medical Genetics Journal Issue: 4 Vol. 51; ISSN 0148-7299; ISSN AJMGDA
- Country of Publication:
- United States
- Language:
- English
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