DNA samples from 161 unrelated patients with autosomal dominant retinitis pigmentosa were screened for point mutations in the rhodopsin gene by using the polymerase chain reaction and denaturing gradient gel electrophoresis. Thirty-nine patients were found to carry 1 of 13 different point mutations at 12 amino acid positions. The presence or absence of the mutations correlated with the presence or absence of retinitis pigmentosa in 174 out of 179 individuals tested in 17 families. The mutations were absent from 118 control subjects with normal vision.

Obesity is a significant and potentially serious health problem in achondroplasia. Body mass indices, weight-to-square of the height ratio (W/H2), and triceps skinfold measurements show that obesity is common. It begins in early childhood and is prevalent at all ages. We recommend that weight be monitored closely in all persons with achondroplasia and that dietary intervention be instituted whenever the body mass indices, W/H2, and triceps skinfold measurements exceed the 95th centile for the general population.

We describe a family carrying a direct duplication of an interstitial segment of the distal long arm of chromosome 4(q31.1q32.3) with a mild clinical phenotype. Affected family members include a 27-year-old woman and 2 of her 4 children, 1 of whom also has Klinefelter syndrome. Although 8 cases of simple duplications or insertions of 4q material have been described, only 3 include bands q31-q32, and these involve additional adjacent material. Affected members of the pedigree reported here have some of the manifestations of previously described cases of duplication 4q, but are less severely affected, suggesting that the genetic material in this region is well tolerated as a partial trisomy.