Mesomelic Dwarfism of the Hypoplastic Ulna, Fibula, Mandible Type

Mesomelic dwarfism of the hypoplastic ulna, fibula, mandible type is a distinct heritable bone dysplasia. The radiographic manifestations appear diagnostic at all ages. Available information indicates an autosomal recessive mode of genetic transmission. No serious physical disability has been documented in people with this condition. The two unrelated affected adults whose cases are reported in this paper were of normal intelligence, as were all patients of previous reports in the medical literature. Previous cases under a variety of names have been reported by Brailsford (1935), M0rch (1941), Book (1950), Lamy and Maroteaux (1960), and Blockey and Lawrie (1963).

Case I: A single 29-year-old white male was seen at a Convention of the Little People of America, a national organization of dwarfs. His short stature was primarily due to striking shortness of the shanks. The forearms were also very short, and the jaw was somewhat hypoplastic. The patient was employed as a draftsman and seemed of high normal intelligence. He denied any disability due to the bony deformities. His parents were of normal stature, and his one sister was also of normal height. The parents were not consanguineous. The shortness of the arms and legs was noted at birth. Motor development was normal, except for failure to walk until the age of three years.

On physical examination, the patient's clinical measurements were as follows: height, 129.5 cm (4 ft. 3 in.); weight, 56.8 kg (125 lb.); arm span, 109 cm; crown-pubis, 87 cm; pubis-heel, 49 cm; acromioclavicular joint to olecranon, 22 cm on the left and 21 cm on the right; olecranon to ulnar styloid, 9 cm bilaterally.

The mandible was somewhat hypoplastic. Except for lop ears, no abnormalities of the head were noted. The trunk appeared essentially normal. There was a mild exaggeration of the normal lumbar lordosis. Both the upper and lower extremities were very short. While all segments were short, the middle segments, i.e., the forearms and shanks, were most affected, and the hands and feet were only slightly affected. The hands were ulnarly deviated at the wrist, and there was some limitation of dorsiflexion of the wrist joints. The motion of other joints was normal. Muscle development was good (Fig. 1).

A complete radiographic skeletal survey was carried out, and this will be discussed along with the radiographic studies obtained at two days and approximately eighteen months of age (see section on radiographic findings).

Case II: A single 42-year-old white female was seen at the same Convention. She presented a clinical appearance identical to Case I except that she was mildly obese and several inches shorter. She was a college graduate and held a responsible managerial position. She stated that she had several normal-size brothers and sisters, and that her parents were likewise of normal stature.