Detection of a recurring mutation in the human growth hormone-releasing hormone receptor gene.

OBJECTIVE: Mutations in the gene encoding for the GH-releasing hormone receptor (GHRHR) have been recently described in patients with familial isolated GH deficiency (IGHD) type IB. To date, all reported mutations have been found in kindreds sharing common ancestors. The only exception is a T to A transversion which causes a substitution of histidine for leucine in codon 144 (L144H) and creates a DraIII restriction site. This mutation was described in two families with different ethnic background residing in two different continents (Europe and North America).
DESIGN: We searched for GHRHR mutations in a new family with IGHD from a third continent (South America) and found the affected individuals to be homozygous for the same L144H change. We performed linkage analysis with intra- and para-genic polymorphisms to determine if the three families carrying the L144H allele are related.
RESULTS: Linkage analysis studies demonstrated that one of the three families does not share the same para- and intragenic GHRHR polymorphisms with the other two.
CONCLUSIONS: The L144H mutation has arisen at least twice and should be considered for initial genetic analysis in patients with familial IGHD in whom the a GHRHR mutation is suspected.