ABSTRACT
Two unrelated children presented with similar clinical features (facial dysmorphism and multiple joint dislocations) suggesting the diagnosis of Larsen syndrome. Both carried an inherited unbalanced translocation resulting in partial trisomy 1q and partial monosomy 6p. Analysis of skin collagen from one of the probands disclosed a decreased alpha 1/alpha 2 chain ratio of collagen type I, increased thermal stability and increased hydroxylation of proline and lysine. The present findings suggest that, as a result of the chromosome rearrangements, both patients have a mutation on a gene involved in collagen production, located either on chromosome 1q or, more probably, on 6p. It is furthermore suggested that other cases of Larsen syndrome are the result of a similar mutation.
Subject(s)
Chromosome Deletion , Chromosomes, Human, Pair 1 , Chromosomes, Human, Pair 6 , Joint Dislocations/genetics , Trisomy , Adult , Chromosome Banding , Collagen/metabolism , Face/abnormalities , Female , Humans , Infant , Joint Dislocations/diagnosis , Karyotyping , Male , Pedigree , Phenotype , Skin/metabolism , SyndromeABSTRACT
Severe osteopetrosis was diagnosed in utero in two successive pregnancies resulting from an intermarriage. Hydrocephaly and skeletal hyperdensity were detected at 18 weeks of gestation, and fractures at 24 weeks. We report on extensive ultrasound, radiological, and pathological findings, including those on brain and bone. The markedly reduced number of osteoclasts observed in these sibs and the very early fetal involvement suggest that this form of osteopetrosis might represent a new entity: autosomal recessive lethal osteopetrosis.
