Ghotra Satvinder, Jangaard Krista, Pambrun Chantale, Fernandez Conrad Vincent
IWK Health Center, Halifax, Nova Scotia, Canada.
BMJ Case Rep. 2016 Mar 11;2016:bcr2016214381. doi: 10.1136/bcr-2016-214381.
Methemoglobinaemia is a rare cause of cyanosis in newborns. Congenital methemoglobinaemias due to M haemoglobin or deficiency of cytochrome b5 reductase are even rarer. We present a case of congenital methemoglobinaemia presenting at birth in a preterm infant. A baby boy born at 29 weeks and 3 days of gestation had persistent central cyanosis immediately after delivery, not attributable to a respiratory or cardiac pathology. Laboratory methemoglobin levels were not diagnostic. Cytochrome b5 reductase levels were normal and a newborn screen was unable to pick up any abnormal variants of fetal haemoglobin. Genetic testing showed a γ globin gene mutation resulting in the M haemoglobin, called Hb F-M-Fort Ripley. The baby had no apparent cyanosis at a corrected gestational age of 42 weeks. Although rare, congenital methaemoglobin aemia should be considered in the differential in a preterm with central cyanosis and investigated with genetic testing for γ globin chain mutations if other laboratory tests are non-conclusive.
高铁血红蛋白血症是新生儿发绀的罕见原因。由M血红蛋白或细胞色素b5还原酶缺乏引起的先天性高铁血红蛋白血症更为罕见。我们报告一例早产儿出生时即出现先天性高铁血红蛋白血症的病例。一名孕29周零3天出生的男婴出生后立即出现持续性中心性发绀，并非由呼吸或心脏疾病引起。实验室高铁血红蛋白水平无法确诊。细胞色素b5还原酶水平正常，新生儿筛查未发现胎儿血红蛋白的任何异常变体。基因检测显示γ珠蛋白基因突变导致了M血红蛋白，称为Hb F-M-Fort Ripley。该婴儿在矫正胎龄42周时无明显发绀。虽然罕见，但对于有中心性发绀的早产儿，鉴别诊断时应考虑先天性高铁血红蛋白血症，若其他实验室检查无定论，应进行γ珠蛋白链基因突变的基因检测。
