Genetic variations, clinical presentation and treatment outcome of isolated growth hormone deficiency type I and II: case series and review of the literature

Abstract

Purpose: To report a case series of four patients with isolated growth hormone deficiency (IGHD) type I from two Chinese pedigrees and to elucidate phenotype-genotype correlation of IGHD type I and II with GH1 gene alterations in the literature.

Methods: Whole exome sequencing (WES) was performed and a literature review was conducted.

Results: Four patients presented with extreme growth retardation (height -4.74 to -6.50 SDS) and undetectable peak growth hormone (GH) during GH stimulating test. WES revealed a novel homozygous nonsense mutation, c.316delC (p.L106Cfs*35), in GH1 gene in the the first pedigree. Deletions of exon 1-5 in GH1 gene were identified in the second pedigree. Ideal catch-up growth after GH treatment was achieved. 94 patients with IGHD type I and 240 patients with IGHD type II were included in literature review. Patients with IGHD type I exhibited younger age (3.2 vs 6.0 years, P < 0.001), more severe growth retardation (median height -6.50 vs -3.84 SDS, P < 0.001), lower peak GH levels (0.05 vs 1.70 ng/ml, P < 0.001) and a higher dosage of GH (0.22 vs 0.17 mg/kg/week, P = 0.012) compared to patients with IGHD type II. Gross deletions constituted 72.3% of IGHD type I cases, while splicing mutations and missense mutations comprised 54.2% and 45.0% of IGHD type II cases. In patients with IGHD type I harboring gross deletion, an early age of diagnosis correlated with both a higher height SDS at diagnosis and a better response after GH treatment. Height SDS after GH treatment in patients with IGHD type II carrying splicing mutations was negatively correlated with age at diagnosis.

Conclusion: We identified two GH1 gene mutations, c.316delC (p.L106Cfs*35) and deletions of exon 1-5 in four Chinese patients with IGHD type I. They had a good response to GH treatment and gained satisfactory height improvement. Early diagnosis and initiating treatment may lead to a better prognosis.

Keywords: GH1 gene; Catch-up growth; Isolated growth hormone deficiency; Short stature.