Kleefstra syndrome type 2: a case report

Abstract

Background: Heterozygous loss-of-function KMT2C variants have been recently associated with a Kleefstra syndrome type 2 (KLEFS2) characterised by hypotonia, developmental delay, intellectual disability, behavioural problems, distinct craniofacial dysmorphisms, including flattened midface, prominent eyebrows, everted lower lip, and thick ear helices. Thus far, up to 10 patients affected by variants in KMT2C have been described. Aim: To describe clinical and molecular findings identified through whole exome sequencing in a 9-year-old girl affected by KLEFS2 related KMT2C. Patient: The patient presented intrauterine growth retardation, microcephaly, hypotonia and developed severe global development delay, intellectual disability, stereotypic and hypersocial behaviour. She never spoke, except for some incompre hensible sounds. [...].