1q41q42 microdeletion syndrome is a chromosomal anomaly characterized by a severe developmental delay and/or intellectual disability, typical facial dysmorphic features, brain anomalies, seizures, cleft palate, clubfeet, nail hypoplasia and congenital heart disease. The disease is MONDO_0012927 (chromosome 1q41-q42 deletion syndrome). Also known as: 1q41-q42 microdeletion syndrome, 1q41q42 microdeletion syndrome, Del(1)(q41q42), chromosome 1q41-q42 deletion syndrome, isolated cases, monosomy 1q41-q42, monosomy 1q41q42.