<b><i>Background/Aims:</i></b> Pseudohypoparathyroidism type 1a (PHP1a) is a rare genetic disorder. This study aimed to determine the prevalence of sleep apnea in children with PHP1a. <b><i>Methods:</i></b> Nineteen patients with PHP1a between the age of 2 and 21 years were enrolled prospectively using online advertisements. Parents completed a medical history and surveys to assess sleep behavior. Polysomnography records were obtained when available. In addition, 18 subjects were identified in a retrospective chart review of de-identified medical records with 2.3 million patient charts. <b><i>Results:</i></b> Parents reported sleep disturbance (94%) and daytime somnolence (81%) in their children with PHP1a. In the retrospective chart review, 39% had a history of sleep apnea versus 8.8% of a similarly obese control group. In the combined analysis (n = 31), 52% had a history of snoring and 45% had a diagnosis of sleep apnea. Patients were obese with a mean BMI z-score of 2.20 ± 0.59. Patients with sleep apnea were significantly younger than those without a diagnosis (8.1 ± 5.4 vs. 12.8 ± 5.0 years, p = 0.02). <b><i>Conclusions:</i></b> Children with PHP1a have a 4.4-fold greater relative risk of sleep apnea than similarly obese children. Screening for sleep apnea in this population may be warranted to prevent adverse health outcomes
