New evidence for genetic heterogeneity of the Freeman-Sheldon syndrome.

We report on two sibs (a boy and a girl) with the Freeman-Sheldon (FS) syndrome (also called cranio-carpo-tarsal "dysplasia" or whistling face syndrome), born to normal parents. This unusual finding may represent genetic heterogeneity, germinal mutation of an autosomal dominant gene, and an epistatic recessive gene that suppressed the expression of the abnormal gene in the father, his parents being first cousins. The last 2 mechanisms seem less probable.