Unraveling the Enigma of Bangungut: Is Sudden Unexplained Nocturnal Death Syndrome (SUNDS) in the Philippines a Disease Allelic to the Brugada Syndrome?

BACKGROUND: Sudden unexplained nocturnal death syndrome (SUNDS) has been reported worldwide. SUNDS is endemic in Southeast Asia and is colloquially known as Bangungut in the Philippines, Lai Tai in Thailand, and Pokkuri in Japan. Although SUNDS in Thailand and Japan have been determined to be phenotypically, genetically and functionally identical to the Brugada syndrome, the relationship between Bangungut/SUNDS in the Philippines and the Brugada syndrome has not been clarified. This paper explores the concordance between Bangungut/SUNDS and the Brugada syndrome. METHODS: We summarized autopsy studies on Bangungut retrieved from PubMed since 1917 and current epidemiological data on Philippine SUNDS to clarify its diagnostic features. We also reviewed current hypotheses of the pathophysiological mechanism of the Brugada syndrome to explore its applicability to Bangungut/SUNDS. RESULTS: The use of the term Bangungut is confusing as it includes many diseases that may cause SUNDS. However, our review reveals a notable subset of Bangungut, identified as Bangungut/SUNDS with no gross cardiac pathology that conforms to the clinical picture of the folk-belief of Bangungut and of the Brugada syndrome, namely: predominance among male in the 20-40 age range; sudden death during sleep or at rest, usually following ingestion of a large meal at night; and victims were in apparent good health prior to their demise. Current pathophysiological mechanisms of Brugada syndrome seemed plausible explanations for a majority of this subset of Bangungut/SUNDS. CONCLUSION: Bangungut/SUNDS and the Brugada syndrome appear closely related. Pathophysiological mechanisms of the Brugada syndrome may explain the enigma of Bangungut/SUND. Whether Bangungut/SUNDS is phenotypically, genetically and functionally an allele of the Brugada syndrome remains inconclusive due to lack of research data. We therefore proposed a research agenda including genetic testing and pharmacological challenge of probands and their family members suspected of SUNDS to conclusively establish the relationship between these two syndromes.