Mutational screening of the CYP26A1 gene in patients with caudal regression syndrome.
BACKGROUND
The retinoic acid (RA)-catabolizing enzyme Cyp26a1 plays an important role in protecting tailbud tissues from inappropriate exposure to RA. Cyp26a1-null animals exhibit caudal agenesis and spina bifida, imperforate anus, agenesis of the caudal portions of the digestive and urogenital tracts, and malformed lumbosacral skeletal elements. This phenotype closely resembles the most severe form of caudal agenesis in humans. In view of these findings, we investigated a potential involvement of the human CYP26A1 gene in the pathogenesis of caudal regression syndrome (CRS).


METHODS
Mutational screening of 49 CRS patients and 132 controls was performed using denaturing high-performance liquid chromatography and sequencing. Differences in the genotype and allele frequency of each SNP were evaluated by chi(2) analysis. The biological significance of the intronic variants was investigated by transfection assays of mutant constructs and by analysis of the splicing patterns with RT-PCR.


RESULTS
Mutational screening allowed us to identify 6 SNPs, 4 of which (447 C>G, 1134 G>A, IVS 1+10 G>C, and IVS 4+8 AG>GA) are new. In addition, we describe a novel 2-site haplotype consisting of the 2 intronic SNPs. Both single-locus and haplotype analyses revealed no association with increased risk for CRS. The consequences of the 2 intronic polymorphisms on the mRNA splicing process were also investigated. Moreover, using functional and computational methods we demonstrated that both of these intronic polymorphisms affect the intron splicing efficiency.


CONCLUSIONS
Our research did not provide evidence that CYP26A1 has implications for the pathogenesis of human CRS. However, the relationship between CRS risk and the CYP26A1 genotype requires further study with a larger number of genotyped subjects.
De Marco
Patrizia
P
U.O. Neurochirurgia, Istituto G. Gaslini, Genova, Italy.
Merello
Elisa
E
Mascelli
Samantha
S
Raso
Alessandro
A
Santamaria
Andrea
A
Ottaviano
Catherine
C
Calevo
Maria Grazia
MG
Cama
Armando
A
Capra
Valeria
V
D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D004252:DNA Mutational Analysis; D005787:Gene Frequency; D005820:Genetic Testing; D005838:Genotype; D006801:Humans; D008279:Magnetic Resonance Imaging; D011110:Polymorphism, Genetic; D020641:Polymorphism, Single Nucleotide; D000072516:Retinoic Acid 4-Hydroxylase; D012307:Risk Factors; D013116:Spinal Cord / Q000002:abnormalities*; D013118:Spinal Cord Diseases / Q000201:enzymology / Q000235:genetics* / Q000503:physiopathology
D003577:Cytochrome P-450 Enzyme System; D000072516:Retinoic Acid 4-Hydroxylase