Heterogeneous phenotypes of Japanese cases with a growth hormone gene deletion

Summary We studied four Japanese patients with isolated growth hormone (hGH) deficiency from three different families. There was consanguinity in two of the three families, and three patients were second cousins. Each patient was homozygous for a deletion of approximately 7.5 kilobases, which included the hGH-N gene. The deletions in three patients belonging to two different families were associated with the same restriction fragment length polymorphism haplotype, while the deletion of the other patient was associated with a different haplotype. All patients were treated with injections of pituitary hGH. The response to the therapy differed among them, that is, two patients belonging to different families showed a poor response together with the presence of anti-hGH antibodies, while the other two patients belonging to the same family showed a rather good response together with the absence of such antibodies. It is suggested that the production of anti-hGH antibodies is not solely due to the gene deletion, but that an unknown immunological disposition might also be involved.