Obstructive sleep apnea and twins

Purpose: Present an intriguing case of a man suffering of OSA who has a homozygous monochorionic twin. Made a systematic review of the literature to summarize existing data and the reported incidence of OSA in twins. Methods: Case presentation and systematic literature review, according to the PRISMA guidelines about twins and Obstructive sleep Apnea. Results: Our patient had a severe OSA condition with an Apnea Hypopnea index (AHI) of 57.6. This patient had a twin who did not suffer from sleep apnea and presented different oropharyngeal and endoscopic anatomical characteristics. Six eligible studies were identified investigating OSA or OSA-related traits in twins. All studies demonstrated higher concordance among monozygotic than dizygotic twins and substantial heritability estimates (40%-83%), particularly for AHI and ODI. However, non-shared environmental and anatomical factors accounted for considerable phenotypic variability. Conclusion: Despite the genetic factors related to the sleep apnea, differences in anatomical features and lifestyle could contributed to the different expression of OSA.