Familial growth hormone deficiency resulting from a 7.6 kb deletion within the growth hormone gene cluster.

We report on two sibs with familial isolated growth hormone deficiency (IGHD) resulting from homozygosity for a 7.6 kb deletion within the growth hormone gene cluster. The deletion not only affects the structural gene for growth hormone (GH-N) but also alters sequences adjacent to the chorionic somatomammotropin-like (CS-L) gene. In contrast to previously reported cases with IGHD type IA, our two patients responded well to growth hormone substitution and formation of blocking antibodies did not occur.