A rare cause of mental motor retardation: recessive congenital methemoglobinemia type II.
Recessive congenital methemoglobinemia (RCM) is a very rare disorder caused by NADH- cytochrome b5 reductase (cytb5r) deficiency. It has been classified into four types. Type I presents with mild cyanosis due to a significant deficiency of cytb5r in erythrocytes only. In type II, the deficiency occurs in all tissues and causes growth and mental retardation and other neurological impairments. RCM types I and II are caused by a defect in a single gene, which is located on chromosome 22 (locus DIA 1: q 13.31-qter). Prenatal diagnosis is possible. Cyanosis can be well treated by 200-500 mg of ascorbic acid daily; there is no effective therapy for the progressive neurological impairments. This report presents two siblings with central cyanosis, growth retardation, mental retardation, microcephaly, dystonia and hypertonia diagnosed as RCM type II.
Yüksel
Deniz
D
Dr. Sami Ulus Child Health and Diseases Training and Research Hospital, Ankara, Turkey.
Senbil
Nesrin
N
Yilmaz
Deniz
D
Yarali
Neşe
N
Gürer
Y K Yavuz
YK
D001205:Ascorbic Acid / Q000627:therapeutic use; D002675:Child, Preschool; D003241:Consanguinity; D005808:Genes, Recessive; D006801:Humans; D007223:Infant; D008607:Intellectual Disability / Q000175:diagnosis / Q000188:drug therapy / Q000235:genetics*; D008279:Magnetic Resonance Imaging; D008297:Male; D008708:Methemoglobinemia / Q000151:congenital* / Q000175:diagnosis / Q000188:drug therapy / Q000235:genetics*; D035781:Siblings; D014815:Vitamins / Q000627:therapeutic use
D014815:Vitamins; D001205:Ascorbic Acid