Thumbs, Stiff, With Brachydactyly Type A1 And Developmental Delay

Stiff thumbs were accompanied by brachydactyly type A1 (112500) and mental retardation in females in 3 generations of the family reported by Piussan et al. (1983). This is clearly a different disorder from C. S. Lewis symphalangism (185650). Barber et al. (1990) reported an isolated case of stiff thumbs and developmental delay which they thought represented the same disorder as that reported by Piussan et al. (1983). Since the father was 59 years old, new dominant mutation was suspected.