Neonatal Bradypnea as an Under-Recognized Manifestation of Prader-Willi Syndrome: A Case Report.

Prader-Willi syndrome (PWS) is a rare neurogenetic disorder caused by loss of expression of paternally inherited genes within the imprinted 15q11.2-q13 region. Diagnosis during the neonatal period is difficult, as symptoms are often reported in older infants or in childhood. Neonatal hypotonia, poor suck leading to feeding difficulties, and genital hypoplasia are commonly recognized features, but respiratory manifestations have been rarely described and may delay early diagnosis. We report a late-preterm neonate born at 36 weeks' gestation with severe asymmetric intrauterine growth restriction who developed respiratory distress soon after birth, initially attributed to early-onset pneumonia. Despite resolution of sepsis, the infant demonstrated recurrent apnea followed by sustained bradypnea episodes beyond the expected course for gestational age. This was accompanied by marked hypotonia and poor feeding due to impaired suck-swallow-breathing coordination. Neuroimaging and metabolic investigations were unremarkable, prompting further evaluation for central causes of hypoventilation. Targeted whole-exome sequencing with copy-number analysis identified a pathogenic deletion involving the PWS critical region on chromosome 15q11.2-q13, and confirmatory DNA methylation analysis demonstrated loss of the paternal allele, establishing the diagnosis. With supportive care, the respiratory status gradually improved, and the infant was referred for multidisciplinary follow-up, including physiotherapy and endocrine evaluation. This case highlights neonatal bradypnea as a rare and under-recognized early manifestation of PWS and emphasizes the importance of considering this diagnosis in neonates with unexplained respiratory dysregulation and hypotonia to facilitate timely genetic testing and appropriate multidisciplinary management.