Analysis of children with familial short stature: who should be indicated for genetic testing?

Familial short stature (FSS) describes vertically transmitted growth disorders. Traditionally, polygenic inheritance is presumed, but monogenic inheritance seems to occur more frequently than expected. Clinical predictors of monogenic FSS have not been elucidated. The aim of the study was to identify the monogenic etiology and its clinical predictors in FSS children. Of 747 patients treated with growth hormone (GH) in our center, 95 with FSS met the inclusion criteria (pretreatment height ≤−2 SD in child and his/her shorter parent); secondary short stature and Turner/Prader–Willi syndrome were excluded criteria. Genetic etiology was known in 11/95 children before the study, remaining 84 were examined by next-generation sequencing. The results were evaluated by American College of Medical Genetics and Genomics (ACMG) guidelines. Nonparametric tests ev aluated differences between monogenic and non-monogenic FSS, an ROC curve estimated quantitative cutoffs for the predictors. Monogenic FSS was confirmed in 36/95 (38%) c hildren. Of these, 29 (81%) carried a causative genetic variant affecting the growth p late, 4 (11%) a variant affecting GH–insulin-like growth factor 1 (IGF1) axis and 3 (8%) a variant in miscellaneous genes. Lower shorter parent’s height (P = 0.015) and less delayed bone age (BA) before GH treatment (P = 0.026) predicted monogenic FSS. In children with BA delayed less than 0.4 years and with shorter parent’s heights ≤−2.4 SD, monogenic FSS was revealed in 13/16 (81%) cases. To conclude, in FSS children treated with GH , a monogenic etiology is frequent, and gene variants affecting the growth plate are th e most common. Shorter parent’s height and BA are clinical predictors of monogenic FSS

A case of digenic maturity onset diabetes of the young with heterozygous variants in both HNF1A and HNF1B genes

Background: Maturity onset diabetes of the young (MODY) is the most commonly reported form of monogenic diabetes in the pediatric population. Only a few cases of digenic MODY have been reported up to now. Case report: A female patient was diagnosed with diabetes at the age of 7 years and was treated with insulin. A strong family history of diabetes was present in the maternal side of the family. The patient also presented hypomagnesemia, glomerulocystic kidney disease and a bicornuate uterus. Genetic testing of the patient revealed that she was a double heterozygous carrier of HNF1A gene variant c.685C > T; (p.Arg229Ter) and a whole gene deletion of the HNF1B gene. Her mother was a carrier of the same HNF1A variant. Conclusion: Digenic inheritance of MODY pathogenic variants is probably more common than currently reported in literature. The use of Next Generation Sequencing panels in testing strategies for MODY could unmask such cases that would otherwise remain undiagnosed