Genetic analysis of a kindred with X-linked mental handicap and retinitis pigmentosa.
A kindred is described in which X-linked nonspecific mental handicap segregates together with retinitis pigmentosa. Carrier females are mentally normal but may show signs of the X-linked retinitis pigmentosa carrier state and become symptomatic in their later years. Analysis of polymorphic DNA markers at nine loci on the short arm of the X chromosome shows that no crossing-over occurs between the disease and Xp11 markers DXS255, TIMP, DXS426, MAOA, and DXS228. The 90% confidence limits show that the locus is in the Xp21-q21 region. Haplotype analysis is consistent with the causal gene being located proximal to the Xp21 loci DXS538 and 5'-dystrophin on the short arm of the X chromosome. The posterior probability of linkage to the RP2 region of the X chromosome short arm (Xp11.4-p11.23) is .727, suggesting the possibility of a contiguous-gene-deletion syndrome. No cytogenetic abnormality has been identified.
MRC Human Genetics Unit, Western General Hospital, Edinburgh, Scotland.
M A
MA
Aldred
K L
KL
Dry
E B
EB
Knight-Jones
L J
LJ
Hardwick
P W
PW
Teague
D H
DH
Lester
J
J
Brown
G
G
Spowart
A D
AD
Carothers
J A
JA
Raeburn
D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D008040:Genetic Linkage; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics*; D007621:Karyotyping; D008126:Lod Score; D008297:Male; D010375:Pedigree; D012174:Retinitis Pigmentosa / Q000235:genetics*; D014960:X Chromosome