The clinical geneticist and the evaluation of failure to thrive versus failure to feed.

Common clinical genetic referrals for the pediatric patient include a single major or multiple minor anomalies, dysmorphic features, especially when accompanied by developmental delay or intellectual disability, and failure to thrive (FTT). This review provides pediatric definitions of FTT and the genetic differential for FTT, which includes chromosomal disorders, microdeletion/duplication syndromes, uniparental disomy/methylation disorder, disorders of DNA repair, teratogens, metabolic syndromes, and skeletal dysplasias. Three clinical genetics cases highlight challenges in deciphering the cause of FTT. The review concludes with a ten-step approach that might improve diagnostic ability in differentiating FTT cases (those with genetic or other metabolic causes) from "failure to feed," in other words FTT as the direct result of neglect and/or child abuse.