Risk factors for hypospadias in the estrogen receptor 2 gene.
BACKGROUND
Hypospadias is a common inborn error of the male genitalia of complex, and still elusive, etiology. The presence of active estrogen receptors (ESRs) in the developing male urethra, predominantly the ESR2, has suggested a role of estrogens in the otherwise androgen-dependent male genital differetiation. Moreover, imbalances between these two steroid hormones have been suggested to disturb the external genital development. This has been supported by the association between longer (CA)n variants in the ESR2 gene with lower androgen levels as well as with hypospadias.


OBJECTIVE
The aim of this study was to analyze the effect of ESR2 gene variants on the risk to hypospadias.


METHODS
Four haplotype-tagging single nucleotide polymorphisms (rs2987983, rs1887994, rs1256040, and rs1256062), the (CA)n polymorphism, and two additional promoter single nucleotide polymorphisms (rs10483774 and rs1271572), mapping to a transcription factor binding region, were typed and analyzed in a Swedish cohort of 354 boys with nonsyndromic hypospadias and 380 healthy controls.


RESULTS
Association was identified with longer variants of the (CA)n polymorphism in intron 6 and with a region of intense transcription factor binding, in the putative promoter region, mapping to rs2987983 and rs10483774. The two regions are in low-linkage disequilibrium, meaning that they are not necessarily inherited together as a haplotype; logistic regression analysis indicates that these two risk effects are not independent.


CONCLUSIONS
The present study evidences two nonindependent risk factors for hypospadias in the ESR2 gene. We discuss possible mechanisms that explain how these variants may affect male urethral development.
Beleza-Meireles
Ana
A
Department of Molecular Medicine and Surgery, Building CMM 00, Karolinska University Hospital, Solna, SE 171 76 Stockholm, Sweden. Ana.Beleza@ki.se
Kockum
Ingrid
I
Lundberg
Fredrik
F
Söderhäll
Cilla
C
Nordenskjöld
Agneta
A
D016022:Case-Control Studies; D002648:Child; D015331:Cohort Studies; D047629:Estrogen Receptor beta / Q000235:genetics*; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D007021:Hypospadias / Q000235:genetics*; D015810:Linkage Disequilibrium; D008297:Male; D018895:Microsatellite Repeats; D020641:Polymorphism, Single Nucleotide; D012307:Risk Factors
D047629:Estrogen Receptor beta