(AC) Dinucleotide Repeat Polymorphism in Intron 1 of Human EGFR Shows Ethnic Specificities and High Evidence for Association with Breast Cancer

A polymorphic AC repeat in intron 1 of the EGFR gene was genotyped on 352 healthy individuals and 118 women with breast cancer sampled from the Kuwaiti and Tunisian populations. We compared allele frequencies in these populations with published data on various ethnic groups. We found very close similarity between Tunisian and Kuwaiti populations for both allelic and genotypic frequencies and in both control and patient groups. Our analysis revealed clear interethnic differences between populations; in Europeans, allele 16 occurred predominantly, whereas in Tunisia and Kuwait allele 17 was the most frequent and allele 20 predominated in Asians. One hundred twenty-three healthy women, matched with the 118 breast cancer patients, were used as controls to test for associations between AC repeat and cancer risk. Strong evidence for such an association was found for allele 18 when considered alone (χ2=27.04, corrected p=0.0000016, OR=3.94) or with longer alleles (>17 repeats) (χ2=20.21, p=0.0005, OR=2.30). This contrasts with Asian populations where allele 16 was identified as the risk allele, showing allele heterogeneity depending on ethnicity.

Estrogen receptor α gene polymorphisms are associated with idiopathic premature ovarian failure

OBJECTIVE

To assess the role of hormone receptor/binding protein variants in genetic predisposition to premature ovarian failure (POF).

DESIGN

Case-control study.

SETTING

Academic.

PATIENT(S)

Fifty-five POF patients, 107 control women from the general population, and 27 control women who had proven fertility after age 37.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Allele distributions in cases and controls were assessed for genetic association.

RESULT(S)

Allele distributions of polymorphisms at the androgen receptor (AR) gene, estrogen receptor beta (ESR2) gene, sex hormone-binding globulin (SHBG) gene, and FSH receptor (FSHR) gene did not differ between patients and controls. At a repeat in a promoter of the estrogen receptor alpha(ESR1) gene, POF patients had fewer (<18) short repeat alleles than did controls (P=.004 vs. combined controls). Genotypes consisting of two short alleles were found in 36.4% of control women but only 5.5% of POF patients (P<.0001 vs. combined controls). The ESR1 repeat may confer risk for POF in a simple dominant manner in which carriers of a long repeat have a relative risk of 9.7 (95% CI = 2.6 - 35.6).

CONCLUSION(S)

Polymorphisms at the ESR1 gene are associated with POF in this patient population, while those in AR, ESR2, SHBG, and FSHR showed no association. Further studies are necessary to confirm these findings in larger patient samples and to identify the specific predisposing lesion.

(CA)n Microsatellite polymorphism of ERBB-1 in breast cancer

The aim of this study was to determine polymorphism of repeated sequences (CA)(n) in the ERBB-1 gene. The study group included 197 breast cancer patients and 180 healthy women. DNA was isolated from fresh-frozen tumour tissue and from peripheral blood. ERBB-1 (CA)(n) microsatellite polymorphism was examined by polymerase chain reaction (PCR). A polymorphic simple sequence repeat region of 9-23 CA repeats was detected in both groups. Homozygotes comprised 22% and 34% of breast cancer patients and controls, respectively (P=0.009). An allelic imbalance (AI), mostly in the shorter allele, was found in 27% of breast cancer patients. AI occurrence was associated with the lack of oestrogen receptors in tumour cells (P=0.05); otherwise, there were no correlations between histoclinical features and (CA)(n) microsatellite polymorphism of ERBB-1. It was concluded that an allelic imbalance is a common feature in breast cancer patients and may coincide with the lack of oestrogen receptors in tumour cells. The clinical relevance of ERBB-1 microsatellite polymorphism in breast cancer remains to be established.