[Gene mapping in 14 families with X-linked nonspecific mental retardation].
Mental retardation affects 2-3% of the population. The identification of nonspecific X-linked mental retardation genes represents a challenge of considerable medical and scientific importance.


OBJECTIVE
An attempt to identify new genes and mutations in known genes in 14 families with nonspecific X-linked mental retardation.


METHODS
Linkage analysis with microsatellite markers was performed in 14 families with mental retardation segregating as an X-linked feature. Significant lod score (> 2) was obtained only for 2 families, due to insufficient number of analyzed families' members. Known MRX genes located in the linkage intervals were analysed.


RESULTS
Analysis of selected known MRX genes enabled identification of pathogenic mutations in 3 out of 14 families. Sequencing of further candidate genes is in progress. In all families the critical region and the number of genes to analyze was significantly narrowed.


CONCLUSIONS
Linkage analysis in families with mental retardation segregating as an X-linked feature is still a considerable approach leading to identification of new genes, and mutations in known genes. It is a first step of identification of disease background, even in small families with lod score < 2.
Nawara
Magdalena
M
Zakład Genetyki Medycznej, Instytut Matki i Dziecka, ul. Kasprzaka 17a, 01-211 Warszawa. magdalena.nawara@imid.med.pl
Jurek
Marta
M
Bal
Jerzy
J
Mazurczak
Tadeusz
T
D000328:Adult; D002648:Child; D002874:Chromosome Mapping; D005190:Family; D005260:Female; D008040:Genetic Linkage; D006801:Humans; D008126:Lod Score; D008297:Male; D038901:X-Linked Intellectual Disability / Q000235:genetics*; D009154:Mutation; D010375:Pedigree