Aspects neurodéveloppementaux et comportementaux du syndrome isodicentrique du chromosome 15 (idic(15)) : à propos d’un cas

Résumé

Isodicentric syndrome of chromosome 15 (Idic(15)) is a rare chromosomal disorder caused by an inverted dupli- cation of the 15q11–q13 region, resulting in the presence of an extra chromosome. It is characterized by a broad neurodevelopmental phenotype, including hypotonia, psychomotor delay with intellectual disability, language impairment, epilepsy, and autistic traits. Owing to its clinical variability, early diagnosis may be challenging, par- ticularly in the absence of seizures or dysmorphic features. We report the case of a 2-year-and-10-month-old girl, born at term to non-consanguineous parents. At birth, she presented with transient respiratory distress and persistent axial hypotonia, with an otherwise normal phy- sical examination. During follow-up, the patient exhibited global developmental delay, including delayed motor and language acquisition and reduced social interaction, without any seizures to date. Brain MRI was normal. Genetic analysis confirmed the diagnosis of Idic syndrome (15). Management was multidisciplinary (pediatric neurology, speech therapy, physical medicine). This case highlights the early, often subtle, presentation of Idic syndrome(15) in the absence of epileptic seizures or facial dysmorphism, underscoring the need for genetic testing in children with unexplained hypotonia and developmental delay. Early identification allows for the implementation of appropriate multidisciplinary care, which can improve functional outcomes.