[Clinical and genetic analysis of a child with Schaaf-Yang syndrome]

To explore the clinical characteristics and genetic etiology of a child with Schaaf-Yang syndrome (SYS).

Peripheral blood samples of the child and his parents were collected and subjected to whole exome sequencing. Sanger sequencing was used for family constellation verification, and bioinformatic analysis was performed for the candidate variant.

The child, a 1-year-and-9-month-old boy, had clinical manifestations of retarded growth, small penis, and unusual facies. Genetic testing revealed that the child has harbored a novel heterozygous variant of c.3078dupG (p.Leu1027Valfs*28) of the MAGEL2 gene. Sanger sequencing showed that neither parent of the child carried the same variant. The c.3078dupG(p.Leu1027Valfs*28) variant of the MAGEL2 gene has not been included in the databases of ESP, 1000 Genomes and ExAC. According to the Standards and Guidelines for the Interpretation of Sequence Variants of the American College of Medical Genetics and Genomics (ACMG), the variant was judged to be pathogenic.

The c.3078dupG (p.Leu1027Valfs*28) variant of the MAGEL2 gene probably underlay the SYS in this child, which has further expanded the spectrum of the MAGEL2 gene variants.