750 RESTRICTION ENDONUCLEASE STUDIES OF INACTIVE GROWTH HORMONE GENES

Abstract

We have studied DNAs from 8 individuals whose clinical findings and pedigrees were consistent with familial isolated growth hormone deficiency (IGHD). Nuclear DNA was prepared from leukocytes, digested with various restriction endonucleases, subjected to electrophoresis, Southern transferred, and hybridized to 32P-labeled growth hormone (GH) DNA sequences. Restriction patterns of samples from affected individuals in 3 different families with IGHD Type I (autosomal recessive) and 1 family with IGHD Type II (autosomal dominant) were normal; i.e., GH genes were present. Two common polymorphic restriction sites were detected in DNAs of various family members which could be used in linkage analyses. DNA from an individual with IGHD Type IA (autosomal recessive) yielded abnormal patterns following Bgl II, Eco RI plus Bam HI, Hinc II, Pst I, and Sst I digestion. In each digest, one or more fragments (∼2.2 to ∼3.3 kilobases) were absent. These findings suggest that some inactive GH genes are associated with deletions of GH or GH-like sequences.