Phenotypic Heterogeneity of 16p11.2 Microdeletion Syndrome: 5 Case Reports

Abstract

Introduction: 16p11.2 microdeletion syndrome is a rare genetic condition with wide clinical heterogeneity. Individuals may present a normal phenotype or neurodevelopmental pathology, often associated with nonspecific dysmorphology, epilepsy, cardiac anomalies and obesity, among other characteristics. Clinical Cases: Case 1: Male, 11-year-old, with macrocephaly from 4 months, obesity from 2 years, and speech delay; currently diagnosed with intellectual developmental disorder. Case 2: Female, 13-year-old, referred at 4 years due to language delay; at 6 years, early puberty and obesity were identified; currently recognized as having intellectual developmental disorder and attention-deficit hyperactivity disorder (ADHD). Case 3: Male, 5-year-old, referred at 3 years for global developmental delay, mainly in language; family history of intellectual developmental disorder; currently has global developmental delay. Case 4: Male, 6-year-old, referred at 11 months for motor delay; at 18 months, language delay, motor coordination difficulties, and aggressiveness were noted; recently, he was diagnosed with autism spectrum disorder. Case 5: Male, 14-year-old, with macrocephaly and expressive language delay at 2 years; oppositional behavior and ADHD diagnosed, with learning disabilities and overweight. None of the cases have epilepsy or cardiac pathology. All showed 16p11.2 microdeletion in array-CGH studies and received multidisciplinary follow-up. Discussion/Conclusion: 16p11.2 microdeletion syndrome shows significant clinical variability, with common neurodevelopmental involvement. Genetic testing via array-CGH helps establish the etiologic diagnosis, making it essential for individuals with global developmental delay / intellectual developmental disorder or autism spectrum disorder. Early diagnosis enables timely intervention and genetic counseling.