Molecular mechanism of recessive congenital methemoglobinemia in Chinese pedigrees.
OBJECTIVE
To investigate the molecular mechanism of recessive congenital methemoglobinemia (RCM) in Chinese and to establish a gene diagnostic method of polymerase chain reaction-restricted fragment length polymorphism (PCR-RFLP).


METHODS
Total RNA was isolated from the peripheral leukocytes of the propositus and b5R cDNA synthesized by reverse transcription-polymerase chain reaction (RT-PCR). The coding region of b5R cDNA was analyzed by sequencing of the RT-PCR products.


RESULTS
Both propositi A and B were found to be homozygotes for a G to A transition at codon 57 in exon 3, changing a guanine to an adenine. This point mutation was not an artificial occurrence during polymerase chain reaction (PCR), as confirmed by Msp I restriction enzyme analysis of the genomic DNA. Propositus A's mother and propositus B's sister and her nephew were found to be heterozygotes for the mutation.


CONCLUSIONS
A guanine-to-adenine transition at codon 57, replacing arginine with glutamine, was the molecular basis for RCM in two Chinese families.
Wang
Y
Y
Center for Medical Laboratory, Fuzhou General Hospital, Fuzhou 350025, China.
Huang
C
C
Wu
Y
Y
Lan
F
F
Tang
Y
Y
Zhu
Z
Z
D000328:Adult; D044466:Asian People; D003579:Cytochrome Reductases / Q000235:genetics*; D042966:Cytochrome-B(5) Reductase; D018076:DNA, Complementary / Q000235:genetics; D005260:Female; D006801:Humans; D008297:Male; D008708:Methemoglobinemia / Q000151:congenital* / Q000235:genetics*; D010375:Pedigree; D017354:Point Mutation
D018076:DNA, Complementary; D003579:Cytochrome Reductases; D042966:Cytochrome-B(5) Reductase