Genetic Etiology Study Of 68 Short Stature Patients By Targeted Next-generation Sequencing

Objectives:This study was designed to discover the genetic mutations and identify the molecular etiologies in a cohort of short stature patients, and to established a new genetic testing method-targeted NGS in genetic evaluation of short stature and prove its potential utility.Subjects and Methods:A total of 68 short stature patients were recruited in the study. 466 genes implicated in short stature were sequenced parallel by combination of NGS and targeted genomic enrichments. The clinical significances of variants detected in patient were evaluated on the basis of extant clinical guideline.Results:These patients were divided into five categories based on clinical diagnosis, including 20 with GHD,16 with skeletal dysplasia,8 with hypothyroidism,8 with ISS and 16 with short stature combined with other systematic abnormities (syndromic patients). We identified 23 gene variants as the possible genetic causes for 24 (35.3%) of 68 short stature patients, which included 12 (62.5%) of skeletal dysplasia patients, 8 (50%) of syndromic patients,4 (50%) of primary hypothyroidism patients,1 of GHD patients and 1 of ISS patients. Of the variants detected,11 were previously reported and 12 were not reported. Of the 12 skeletal dysplasia patients with possible genetic causes,2 were identified with FGFR3 mutation,1 with NPR2 mutation,2 with COL2A1 mutation,3 with FBN2 mutation,1 with TRAPPC2 mutation and 1 with ARSE mutation. Among the 8 syndromic patients with possible genetic causes,2 were identified with PTPN11 mutation,1 with KRAS mutation,1 with NIPBL mutation,1 with PORCN mutation,1 with a heterozygous deletion in chromosome 17: 1,619,817-1,680,859 (about 60kb),1 with a heterozygous deletion in chromosome 4:994,399-2,837,402 (about 1.8Mb) and 1 with a heterozygous duplication in exon2-exon15 of NF1 gene. The four primary hypothyroidism patients with possible genetic causes included 2 with NKX2-1 mutation,1 with NKX2-5 mutation and 1 with PAX8 mutation. One patient with isolated GHD was identified with a heterozygous deletion of the short arm of X chromosome and a heterozygous duplication of the long arm of X chromosome. One patient diagnosed of ISS was identified with a novel heterozygous duplication in chromosome 14:74964886-75079034.Conclusions:We identified the molecular etiologies in 35.3% of short stature patients by combination of NGS and targeted genomic enrichments. The study demonstrated the efficiency of such a comprehensive genetic evaluation in clinics. It provides a good way to large-scale genetic study of short stature.