Acromicric dysplasia

Acromicric dysplasia is a condition characterized by severely short stature, short limbs, stiff joints and distinctive facial features. Newborns are of normal size, but slow growth over time results in short stature, with an average adult height of about 4 feet 2 inches for women and 4 feet 5 inches for men. The long bones of the arms and legs, and the bones of the hands and feet, are shorter than expected for height. Other skeletal features include delayed bone age, abnormally shaped vertebrae and constrained joint movement, and affected people often develop carpal tunnel syndrome, with numbness, tingling and weakness in the hands and fingers; hip dysplasia can also occur. These problems may need treatment, but most affected people have few limitations in their activities. Children may have a round face, sharply defined eyebrows, long eyelashes, a bulbous nose with upturned nostrils, a long space between the nose and upper lip and a small mouth with thick lips, and these differences become less apparent in adulthood. Intelligence is unaffected and life expectancy is generally normal. The condition is caused by mutations in the FBN1 gene, which makes the protein fibrillin-1; most of the mutations change single protein building blocks and reduce and disorganize the microfibrils that store the growth factor TGF-beta, leaving it abnormally active, although the mechanisms are unclear. It is inherited in an autosomal dominant pattern; most cases result from new mutations in people with no family history, and in other cases a person inherits the mutation from one affected parent. It is rare and its prevalence is unknown. Its other name is ACMICD.