Cytochrome P450 oxidoreductase deficiency: identification and characterization of biallelic mutations and genotype-phenotype correlations in 35 Japanese patients.
BACKGROUND
Cytochrome P450 oxidoreductase (POR) deficiency is a rare autosomal recessive disorder characterized by skeletal dysplasia, adrenal dysfunction, disorders of sex development (DSD), and maternal virilization during pregnancy. Although multiple studies have been performed for this condition, several matters remain to be clarified, including the presence of manifesting heterozygosity and the underlying factors for clinical variability.


OBJECTIVE
The objective of the study was to examine such unresolved matters by detailed molecular studies and genotype-phenotype correlations.


METHODS
Thirty-five Japanese patients with POR deficiency participated in the study.


RESULTS
Mutation analysis revealed homozygosity for R457H in cases 1-14 (group A), compound heterozygosity for R457H and one apparently null mutation in cases 15-28 (group B), and other combinations of mutations in cases 29-35 (group C). In particular, FISH and RT-PCR sequencing analyses revealed an intragenic microdeletion in one apparent R457H homozygote, transcription failure of apparently normal alleles in three R457H heterozygotes, and nonsense mediated mRNA decay in two frameshift mutation-positive cases examined. Genotype-phenotype correlations indicated that skeletal features were definitely more severe, and adrenal dysfunction, 46,XY DSD, and pubertal failure were somewhat more severe in group B than group A, whereas 46,XX DSD and maternal virilization during pregnancy were similar between two groups. Notable findings also included the contrast between infrequent occurrence of 46,XY DSD and invariable occurrence of 46,XX DSD and pubertal growth pattern in group A mimicking that of aromatase deficiency.


CONCLUSIONS
The results argue against the heterozygote manifestation and suggest that the residual POR activity reflected by the R457H dosage constitutes the underlying factor for clinical variability in some features but not other features, probably due to the simplicity and complexity of POR-dependent metabolic pathways relevant to each phenotype.
Fukami
Maki
M
Research Institute, National Center for Child Health and Development, Tokyo 157-8535, Japan. mfukami@nch.go.jp
Nishimura
Gen
G
Homma
Keiko
K
Nagai
Toshiro
T
Hanaki
Keiichi
K
Uematsu
Ayumi
A
Ishii
Tomohiro
T
Numakura
Chikahiko
C
Sawada
Hirotake
H
Nakacho
Mariko
M
Kowase
Takanori
T
Motomura
Katsuaki
K
Haruna
Hidenori
H
Nakamura
Mihoko
M
Ohishi
Akira
A
Adachi
Masanori
M
Tajima
Toshihiro
T
Hasegawa
Yukihiro
Y
Hasegawa
Tomonobu
T
Horikawa
Reiko
R
Fujieda
Kenji
K
Ogata
Tsutomu
T
D000293:Adolescent; D000305:Adrenal Cortex Hormones / Q000378:metabolism; D000483:Alleles; D001847:Bone Diseases / Q000201:enzymology / Q000235:genetics; D045744:Cell Line, Tumor; D002648:Child; D002675:Child, Preschool; D003577:Cytochrome P-450 Enzyme System / Q000172:deficiency* / Q000235:genetics*; D005091:Exons / Q000235:genetics; D005260:Female; D018628:Gene Dosage; D014644:Genetic Variation; D005838:Genotype; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007223:Infant; D007564:Japan; D008297:Male; D009154:Mutation / Q000235:genetics; D010088:Oxidoreductases / Q000172:deficiency* / Q000235:genetics*; D010641:Phenotype; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012741:Sexual Maturation; D055815:Young Adult
D000305:Adrenal Cortex Hormones; D003577:Cytochrome P-450 Enzyme System; D010088:Oxidoreductases