X-linked cubitus valgus with mental retardation and typical face.

In 1973, Jones and Smith described two maternal male first cousins with a similar pattern of malformation, including mental retardation, cubitus valgus, and unusual facies. The purpose of this report is to describe three additional cases, a 10-year-old male and his 30-year-old maternal uncle and an unrelated 15-year-old boy, bringing to five the total number of individuals with this disorder. The principal features include moderate mental retardation, mild microcephaly, a short philtrum, deep-set, downslanting palpebral fissures, multiple nevi, and striking cubitus valgus. Documentation of this disorder in two maternal male first cousins as well as in a male and his maternal uncle support an X-linked recessive mode of inheritance for this condition.