Growth hormone (GH) mutations and sequence variants in children with growth hormone deficiency (GHD)

Background. Isolated growth hormone deficiency (IGHD) exhibits genetic hete­rogeneity in both familial and sporadic cases. The GH1 gene is a mutational hotspot among the five genes responsible for growth hormone deficiency (GHD), frequently causing short stature. The study aimed to screen for two common GH1 gene mutations prevalent in Asian populations among Sri Lankan children with biochemically confirmed GHD, and to compare sequence variations with known variants in other populations. Methods. Genomic DNA was extracted from 10 children with confirmed GHD attending Lady Ridgeway Hospital, Colombo. PCR amplification was optimized for two primer sets targeting hotspot regions: the deletion-prone homologous flanking regions and the exon 3-intron 3-exon 4 region. Restriction fragment length polymorphism (RFLP) analysis was performed using SmaI enzyme (to detect the common 6.7 kb deletion) and NlaIII enzyme (to detect the G>A transition at the intron 3 splice donor site). Direct DNA sequencing was subsequently conducted for variant confirmation. Results. SmaI digestion revealed heterozygous-like patterns in 3 out of 10 samples (30 %); it reflects heterozygosity or residual allele abnormalities. The remaining 7 samples (70 %) showed banding patterns identical to healthy controls. NlaIII digestion showed no mutations in any of the 10 samples (0/10, 0 %), with all patient samples displaying patterns indistinguishable from healthy DNA. Conclusion. The two mutations commonly found in Asian populations were largely absent in this Sri Lankan cohort, suggesting that short stature in this population may result from alternative GH1 mutations or other genetic variants, warranting comprehensive genomic screening studies.