The gene that causes MSS has not yet been identified, so prenatal diagnosis can not yet be done. MSS is very rare. About 100 hundred cases have been reported in the literature. It has been reported in numerous countries including the United States, Japan, Scandinavia, Italy, England, France, Kuwait, and others. By the age of one, small stature usually becomes more apparent.
Cataracts appear in early childhood and can develop quickly.
The child generally achieves good mobility with a walker or crutches, but independent walking is unlikely due to ataxia and muscle weakness. Diagnosis is based primarily on symptoms, but research is leading to diagnostic procedures and eventually genetic testing. The medical literature reports a wide-range of scenarios for the MSS patient. The variation is probably due to a combination of individual differences, increased availability of early intervention and educational opportunities sinces the 1960s, and uncertainty in diagnosis. Most patients continue to use walkers and crutches for mobility.