Young Thai sisters with growth hormone insensitivity or Laron syndrome

Background: Growth hormone insensitivity (GHI) or Laron syndrome can result from GH receptor (GHR) or postreceptor defects, such as in GH binding or transduction, or insulin-like growth factor 1 (IGF-1) synthesis. Multiple defects in GHI have been reported in cohorts from the Middle East, Ecuador, and the Mediterranean, but rarely reported from Southeast Asia. Methods: Genomic DNA was isolated from peripheral blood leukocytes of young Thai sisters with severe short stature. Coding exons, including the intronic boundaries of the GHR were amplified from genomic DNA by PCR, and products were purified and sequenced. Serum GH, IGF-1, and IGF binding protein-3 were assayed immunometrically. Results: We found an extreme GHI phenotype and a homozygous mutation in exon 7 of GHR. Conclusions: This mutation can cause a new donor splice site and interfere with mRNA splicing. To our knowledge, these are first cases of Laron syndrome in Thais confirmed by genotyping.