ABSTRACT
OBJECTIVES: Foetal karyotyping is a basic tool used to diagnose the most common genetic syndromes. Although new molecular methods such as FISH, MLPA or QF-PCR allow rapid prenatal testing, they are of limited value when diagnosing less frequent chromosomal abnormalities. Chromosomal microarray analysis offers higher test resolution than traditional karyotyping and has been recommended as first-line genetic testing in prenatal diagnosis. The aim of the study was to confirm whether foetal karyotyping remains a valid approach to prenatal diagnosis by analysing its performance in a large population of pregnant women with a high risk of chromosomal aberration. MATERIAL AND METHODS: An analysis was performed of 2169 foetal karyotypes from two referral university centres for prenatal diagnostics in Lodz, Poland. RESULTS: Amniocentesis and foetal karyotyping were performed when screening methods had indicated a high risk of chromosomal aberration, or when prenatal ultrasound had proved foetal abnormality. The study group included 205 (9.4%) abnormal foetal karyotypes. Rare aberrations were observed in 34 cases (e.g., translocations, inversions, deletions and duplication). A marker chromosome was present in five cases. CONCLUSIONS: One third of the chromosomal abnormalities observed in the prenatal tests were rarer aberrations (i.e., not trisomy 21, 18 or 13). As many of these could not be detected by the new molecular methods, foetal karyotyping remains an important component of prenatal diagnosis.
ABSTRACT
INTRODUCTION: Recurrent miscarriage is a serious clinical problem that affects 1-5 % of all couples trying to conceive. Although the incidence of Smith-Lemli-Opitz Syndrome (SLOS, OMIM #270400), an autosomal recessive condition caused by variants in the DHCR7 gene, is very low, (1:83 000), the observed carrier frequency of DHCR7 gene variants in the Polish population is high, ranging from 1:24 to 1:31. It is possible that this carriage may be responsible for early pregnancy loss. OBJECTIVES: The aim of the study is to determine the carrier frequency of the p c.976 G>T (p.Val326Leu) and c.452 G>A (p.Trp151Ter) variants in the DHCR7 gene in patients experiencing recurrent miscarriage. METHODS: The study group included 480 patients: a study group of 380 with at least 2 miscarriages before the 20th week of pregnancy, and a control group of 100 who had not experienced miscarriage. The variants were identified by genotyping: c.976 G>T (p.Val326Leu) by the TaqMan® SNP Genotyping Assay system, and c.452 G>A (p.Trp151Ter) using the BfaI restriction enzyme. Statistical analysis was performed using R software. RESULTS: No examples of c.976 G>T (p.Val326Leu) were found in either group. c.452 G>A (p.Trp151Ter) was found in 22 participants from the study group and 4 from the control group; however, this difference was not significant (Chi2 test p = 0.61). CONCLUSIONS: Being a carrier of the c.976 G>T (p.Val326Leu) and c.452 G>A (p.Trp151Ter) variants in theDHCR7 gene is not a risk factor for recurrent miscarriage in the Polish population.
