Metacarpal index in Marfan's syndrome and in constitutional tall stature.

The metacarpal index (MCI) in 54 children with constitutional tall stature was mean (SD) 8.65 (0.8) and in 55 with Marfan's syndrome 9.15 (0.9). Indices in both groups showed arachnodactyly and differed from those found in normal individuals (< 7.9). Because the MCI is a poor discriminator patients with tall stature or clinical signs of arachnodactyly should be examined for additional signs of Marfan's syndrome or other hereditary disorders of connective tissue.