Hexasomy 13q31.3q34 due to two marker chromosomes with inverted duplication in a fetus with increased nuchal translucency.

BACKGROUND: Small supernumerary marker chromosomes are structurally rearranged chromosomes that can be formed from different chromosomal fragments and cannot be identified using chromosomal banding analysis. Their examination has to be complemented by additional analyses like fluorescent in situ hybridization or array comparative genomic hybridization. METHODS: We report on partial hexasomy of chromosome 13q in a fetus of a pregnant woman referred to genetic counseling because of increased fetal nuchal translucency and increased risk of trisomy 21 and trisomy 18 in first-trimester combined prenatal screening. Using chromosome banding analysis, in situ hybridization and array comparative hybridization we revealed the presence of two marker chromosomes with inverted duplication resulting in hexasomy of a 22.6 Mbp fragment in chromosomal region 13q31.3-13q34 with the lack of chromosome 13 centromere. RESULTS: The fetus presented dysmorphic facial features, head and body disproportion, wide neck, ambiguous genitalia, incorrect position of the anus, and symmetrical shortening of the long bones were present in our described case. Some of these features were in accordance with other published cases. Other most often described features in tetrasomy were: microphtalmia or other major eye defects, ear abnormalities and deafness, hemangiomata, hypotelorism, severe learning disability and seizures. Despite a low risk of recurrence for small supernumerary marker chromosomes the possibility of germ line mosaicism exists, thus genetic counseling was offered to the examined family. CONCLUSION: A full characterization of small supernumerary marker chromosomes in fetal karyotype is necessary for pregnancy prognosis and genetic counseling.

CYP1A1 Ile462Val polymorphism and colorectal cancer risk in Polish patients.

Colorectal cancer (CRC) is an epidemiological problem of a great importance in Poland; each year approximately 14,600 new cases of the disease are diagnosed. Mortality associated with CRC reaches approximately 10,400 cases per year (according to the National Cancer Registry). The 5-year survival rate is approximately 25 %, which is one of the lowest rates in Europe. The etiology of sporadic colorectal cancer (CRC) is multifactorial and has been attributed to an interplay between both environmental and genetic risk factors. In addition, there is a general consensus that genetic factors may modulate the influence of environmental insults. Following these assumptions, we performed a study on widely described polymorphisms in xenobiotic-metabolizing enzymes and DNA repair genes which may influence individual susceptibility to cancer. We selected five candidate polymorphisms in following genes: ERCC1 Asp118Asn (rs11615), XPC i11C/A (rs2279017), XRCC3 Met241Thr (rs861539) CYP1A1 Ile462Val (rs1048943) and NAT2 A803G (rs1208) and assessed the importance of chosen SNPs on groups consisting of 478 CRC patients and 404 controls. Only CYP1A1 Ile462Val was statistically significant in CRC patients over 50 years old: OR 2.05 (1.29-3.28); p = 1.25E-02 and this association was more pronounced in the female group of CRC patients after the age of 50: OR 2.72 (1.43-5.14); p = 1.14E-02.