The spectrum of "complicated spastic paraplegia, MASA syndrome and X-linked hydrocephalus". Contribution of DNA linkage analysis in genetic counseling of individual families.

X-linked hydrocephalus and the X-linked MASA syndrome (Mental retardation. Adducted thumbs, Shuffling gait and Aphasia) both have a variable clinical spectrum with great overlap. Data from DNA linkage analysis placed the locus for both conditions at Xq28. On clinical and molecular grounds it has been hypothesized that both MASA syndrome and X-linked hydrocephalus are caused by a mutation in the same gene at Xq28. There is no significant clinical marker in the obligate female carriers and prenatal diagnosis by ultrasound is not reliable; DNA analysis can offer an improved genetic counseling for the families and more reliable prenatal diagnosis. In the gene encoding for Ll, a neural cell adhesion molecule and located at Xq28, several different mutations have been reported in X-linked hydrocephalus families and in a MASA family. We report data on DNA linkage analysis in 6 families with X-linked hydrocephalus/MASA syndrome. These data illustrate the importance of DNA linkage analysis in the individual family; they also show, however, the problem of studying small families. Genetic heterogeneity cannot be excluded.