Ulnar Hypoplasia
Clinical Features
Fryns et al. (1988) described an apparently new form of mesomelia in father and daughter. Other than hypoplasia of the ulna with severe radial bowing, there were no other abnormalities in the skeleton; specifically, the tibiae and fibulae were completely normal. The father was 179 cm tall, with an arm span of 144 cm. At age 6 months, the daughter was at the fifth percentile for length. The father and mother of the father were 47 and 45 years old, respectively, at the time of his birth.
Megarbane and Ghanem (2005) reported a Lebanese father and son with isolated upper limb mesomelic dysplasia and normal stature. The 8-year-old boy had prominent bowed radii, limitation of motion of the elbows, dislocation of the radial heads, prominent joints, and ulnar deviation of both hands. X-ray examination revealed short and thick ulnae, and short, thick, and bowed radii, with subluxation of the radial heads. The boy's father had a milder phenotype, with more involvement of the right arm than the left. The parents were consanguineous, but the mother and an older sib were unaffected.
InheritanceMegarbane and Ghanem (2005) noted that the vertical mode of transmission in their family and in the family reported by Fryns et al. (1988) suggested autosomal dominant inheritance with variable expressivity.