{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,19]],"date-time":"2026-05-19T13:15:29Z","timestamp":1779196529802,"version":"3.51.4"},"reference-count":17,"publisher":"BMJ","issue":"5","content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Case Rep"],"accepted":{"date-parts":[[2026,4,30]]},"published-print":{"date-parts":[[2026,5]]},"abstract":"<jats:p>\n                    Neonatal cyanosis is commonplace, usually from respiratory or cardiac causes. Consideration of alternative or combined aetiologies was required when a 3-hour-old term male neonate with central cyanosis, low oxygen saturation (SpO\n                    <jats:sub>2<\/jats:sub>\n                    ), and persistent pulmonary hypertension of the newborn (PPHN) confirmed on echocardiography, failed to respond to PPHN interventions. The high oxygen saturation gap and methemoglobin (MetHb) level of 16.2% shifted the working diagnosis to methemoglobinaemia. Possible triggering drugs were stopped and methylene blue was given without effect, prompting testing for haemoglobin variants. Though the SpO\n                    <jats:sub>2<\/jats:sub>\n                    remained in the mid-80s, MetHb levels decreased, pulmonary pressures normalised by day of life (DOL) 4, and he was discharged home on DOL 22. Diagnostic testing confirmed the haemoglobin F-M-Fort Ripley mutation (\n                    <jats:italic>HBG2<\/jats:italic>\n                    : c.277C&gt;T), a variant that affects fetal haemoglobin only and is therefore self-limited. In this case, the concurrent presentation of PPHN and congenital methaemoglobinaemia created significant diagnostic and therapeutic challenges.\n                  <\/jats:p>","DOI":"10.1136\/bcr-2025-271784","type":"journal-article","created":{"date-parts":[[2026,5,19]],"date-time":"2026-05-19T12:55:32Z","timestamp":1779195332000},"page":"e271784","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Neonatal cyanosis: exploring the complexity of coexisting congenital methemoglobinaemia and pulmonary hypertension"],"prefix":"10.1136","volume":"19","author":[{"given":"Kayla","family":"Sliskovic","sequence":"first","affiliation":[{"name":"Paediatrics, Western University, London, Ontario, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Abdullah","family":"Aljughaiman","sequence":"additional","affiliation":[{"name":"Paediatrics, Western University, London, Ontario, 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