2026 Volume 53 Issue 3 Pages 63-68
An eighteen-month-old male infant was brought to our department with a chief complaint of developmental delay. Physical examination revealed no abnormalities. Magnetic resonance imaging of the head showed no morphological abnormalities, and G-band analysis revealed a normal 46,XY karyotype. Microarray chromosomal testing was performed to investigate the unexplained psychomotor developmental delay, which identified uniparental disomy of chromosome 15. Additional DNA methylation test confirmed the diagnosis of Angelman syndrome. Therapeutic interventions were initiated based on the natural history of Angelman syndrome and associated sleep disorders. Angelman syndrome due to uniparental disomy is often mild, making diagnosis challenging. In this case, combining microarray chromosome analysis and DNA methylation testing ― both covered by insurance in recent years ― enabled early diagnosis and therapeutic intervention. In the future, genetic tests currently performed only in research settings will likely be covered by health insurance and increasingly utilized in clinical practice in Japan. Therefore, the expanding knowledge and information regarding genetic testing will become increasingly important.
