Genetic diagnosis of congenital hypopituitarism in Turkish patients by a target gene panel: novel pathogenic variants in GHRHR, GLI2, LHX4 and POU1F1 genes

ABSTRACT Objective: Congenital hypopituitarism (CH) is a rare disease characterized by one or more hormone deficiencies of the pituitary gland. To date, many genes have been associated with CH. In this study, we identified the allelic variant spectrum of 11 causative genes in Turkish patients with CH. Materials and methods: This study included 47 patients [21 girls (44.6%) and 26 boys (55.4%)] from 45 families. To identify the genetic etiology, we screened 11 candidate genes associated with CH using next-generation sequencing. To confirm and detect the status of the specific familial variant in relatives, Sanger sequencing was also performed. Results: We identified 12 possible pathogenic variants in GHRHR, GH1, GLI2, PROP-1, POU1F1, and LHX4 in 11 patients (23.4%), of which six were novel variants: two in GHRHR, two in POU1F1, one in GLI2, and one in LHX4. In all patients, these variants were most frequently found in GLI2, followed by PROP-1 and GHRHR. Conclusion: Genetic causes were determined in only 23.4% of all patients with CH and 63% of molecularly diagnosed patients (7/11) from consanguineous families. Despite advances in genetics, we were unable to identify the genetic etiology of most patients with CH, suggesting the effect of unknown genes or environmental factors. More genetic studies are necessary to understand the etiology of CH.

Rare Frequency of Mutations in Pituitary Transcription Factor Genes in Combined Pituitary Hormone or Isolated Growth Hormone Deficiencies in Korea

PURPOSE: Congenital hypopituitarism is caused by mutations in pituitary transcription factors involved in the development of the hypothalamic-pituitary axis. Mutation frequencies of genes involved in congenital hypopituitarism are extremely low and vary substantially between ethnicities. This study was undertaken to compare the clinical, endocrinological, and radiological features of patients with an isolated growth hormone deficiency (IGHD) or combined pituitary hormone deficiency (CPHD). MATERIALS AND METHODS: This study included 27 patients with sporadic IGHD and CPHD. A mutation analysis of the POU1F1, PROP1, LHX3, LHX4, and HESX1 genes was performed using genomic DNA from peripheral blood leukocytes. RESULTS: IGHD and CPHD were observed in 4 and 23 patients, respectively. Mean age at diagnosis was 8.28±7.25 years for IGHD and 13.48±10.46 years for CPHD (p=0.37). Serum insulin-like growth factor-1 and peak growth hormone (GH) levels following GH stimulation tests were significantly lower in patients with CPHD than in those with IGHD (p<0.05). Sellar MRI findings revealed structural abnormalities in 3 patients with IGHD (75%) and 21 patients with CPHD (91.3%) (p=0.62). A mutation analysis identified homozygous p.R109Q mutations in HESX1 in a patient with CPHD. Patients with CPHD had more severe GHD than those with IGHD. CONCLUSION: The frequency of defects in the genes encoding pituitary transcription factors was extremely low in Korean patients with congenital hypopituitarism. Environmental factors and the impact of other causative genes may contribute to this clinical phenotype.

Molecular characterization in a case of isolated growth hormone deficiency and further prenatal diagnosis of an unborn sibling.

Familial isolated growth hormone deficiency (GHD) type 1 is characterized by an autosomal recessive pattern of inheritance with varying degrees of phenotypic severity. We report a proband, with isolated GHD (IGHD) with very early growth arrest and undetectable levels of GH. Homozygous complete deletion of the GH1 gene was identified by real‑time/quantitative polymerase chain reaction (RT/q‑PCR) and confirmed by an independent molecular genetic method; the multiplex ligation‑dependent probe amplification (MLPA) technique. Prenatal diagnosis was offered for the subsequent pregnancy in the mother of our proband. Identical heterozygous deletion of the GH1 gene was detected in both parents. The fetus had a similar homozygous deletion of the GH1 gene. We thus report a unique case with a confirmed mutation in GH1 gene in the proband followed by prenatal detection of the same mutation in the amniotic fluid which to our knowledge hitherto has not been documented from India.

Studies of GH gene defects in familial Isolated Growth Hormone Deficiency (IGHD).

One family with isolated GH deficiency (IGHD) was Studied. To determine GHI gene deletions, PCR and Southern blot analyses were used. None of the possible deletions were found in the subjects but the GH1 gene mutation was found. The family consisted of parents (both 140 cm) and their three children with isolated GHD. The daughter and two sons were first seen between 2.9 and 5.3 years of age when their HtSDSs were -2.2 to -3.6, and peak GHs were 0.9 to 4.0 mg/ml. The GH1 gene change was found in G-->A substitution at +28 in the intervening sequence or intron 3 (IVS3+28 G-->A). This change is a dominant-negative mutation which has never occurred in any reports in any reports in Thailand and we were the first group to report here. The segregation which and expression studies of the IVS3+28 G-->A variant are underway to confirm whether it is a new dominant-negative mutation that causes GHD by perturbing mRNA splicing.

Molecular studies in growth hormone gene deletions in patients with isolated growth hormone deficiency.

Human GH deficiency (GHD) occurs in 1 in 4,000-10,000, and up to 30 percent of cases have an affected first degree relative suggesting many cases may be familial. To determine the GHD cases cased by GH gene defects we analyzed the GH genes of 90 consecutive cases. Genomic DNAs were used for PCR amplification of 2.7 kb fragments containing subjects’ GH gene; these PCR products were subjects to determine GH gene deletions. PCR products of 1900 and 1919 bp were obtained. By using the combination of restriction enzymes BglI, HaeII and SmaI to digest these PCR products, the various sizes of GH gene deletion can be detected. None of the possible deletions was found in these patients by either PCR or Southern blot analysis.