Phelan-McDermid syndrome in a Chinese pediatric patient: A case report - new heterozygous mutations lead to PMS.

Phelan-McDermid syndrome, also known as chromosome 22q13.3 deletion syndrome, is a genetic disorder primarily caused by a chromosome 22q13.3 deletion or mutation. The primary clinical manifestations include intellectual disability, delayed language development, behavioral delays, hypotonia, autism spectrum disorder, mild deformities, and epilepsy. The clinical symptoms of this disease are associated with chromosomal deletions, and mild cases may be easily misdiagnosed as autism spectrum disorder. A 3-year-old girl was admitted for "chromosomal abnormality (heterozygous deletion) and developmental delay." After admission, we found that the child's overall growth retardation (mainly language and movement) and accompanied by obvious social disorders, but the muscle strength and muscle tension were basically normal; brain magnetic resonance imaging and electroencephalography were not obvious abnormalities. Gene copy number variation analysis showed that there was a new pathogenic heterozygous deletion of 1.21 Mbp in the chromosome 22:50014294-51220722 region, and the genomes of both parents were wild-type. Combined with the clinical manifestations of the child, the child was finally diagnosed with mild Phelan-McDermid syndrome. The children received systematic rehabilitation treatment. Her language, social, and motor abilities were significantly improved. Phelan-McDermid syndrome may be easily misdiagnosed as autism spectrum disorder. Our report enriches the clinical phenotype of Phelan-McDermid syndrome and provides a realistic and reliable basis for clinicians.