IMPE Abstracts

Introduction: GH1 was the first gene associated with isolated GH deficiency (IGHD) due to a gene deletion described in 1981. Subsequently, frameshift, homozygous missense and nonsense allelic variants, and splice site allelic variants causing GHD were reported.

Aim: Use whole exome sequencing (WES) in the search of variants in known genes and also new genes associated to IGHD and determine the effect of variants.

Cohort: Sixteen among 250 patients followed in an endocrinology outpatient clinic were selected due to IGHD with normally located posterior pituitary lobe on MRI.

Methods: WES was performed in 16 patients from 15 families at the Broad Institute using Agilent’s SureSelect Human All Exon Kit v2 in Illumina HiSeq2000 platform. Whole GH1 from one patient and her mother were cloned into a plasmid and transiently transfected in AtT20 using the plasmid containing the insert with exons/introns. Whole GH1 transfection was used to evaluate alternative splicing to check isoforms (22kD and 17.5kD) and measure GH production and secretion in the AtT20 media using Immulite 2000, done in triplicate at least twice. Allelic variants with MAF<1% were evaluated in the public databases (GnomAD and AbraOM).

Results: A female patient harbored a heterozygous GH1 allelic variant c.620A>G (chr17:61994703T>C) leading to amino acid change p.Gln207Arg or p.Gln181Arg (if peptide signal is discounted) that was absent in the public databases. She was born small for gestational age (SGA) from non-consanguineous parents. Her height at 7 years and 10 months was –4.6 SDS, GH peak at ITT was 1.55ng/ml and it was repeated after completing linear growth presenting GH peak of 0.7ng/ml and no other pituitary hormone deficiencies. The allelic variant was confirmed as de novo since it was absent from her parents and sister. No alteration in the isoforms were found, but the transient transfection showed decreased GH levels. Plasmid sequencing showed 6 intronic allelic variants present exclusively in the proband and absent in the mother and also in the public databases.

Conclusion: We present a patient with GH1 allelic variant absent in the database that showed expected isoforms and decreased GH secretion with exclusive intronic variants that need to be further explored.