Jyothi Kiran Kohli1
Genetic diseases are one of the major causes of hospital admissions due to disability and mortality particularly among children (1:5 children of hospital admission either partially/completely) as distribution of genetic diseases is not related to socioeconomic background, which implies that developing world has a large number of genetic diseases largely left uncared for, i.e. overall incidence of foetal/neonatal loss due to genetic/genetic environmental causes are as follows: 1:50 newborns have major congenital abnormality, 1:100 have a unifactorial disorder, 1:200 have a major chromosomal abnormality before birth. Diagnosis of chromosomal anomalies in foetus is one of the most important challenges in modern perinatology as invasive or noninvasive methods.
The aim of the study is to review on cytogenetic evaluation of CVS obtained (transcervically) during first trimester of pregnancy by direct karyotyping of tissue.
MATERIALS AND METHODS
This study was conducted in 2001 in Department of Anatomy along with Obstetrics and Gynaecology Department, LNJP Hospital. 37 healthy cases with 6-12 weeks of gestational age coming for medical termination of pregnancy were included in the study. After written informed consent for procedure, ultrasound-guided transcervical chorionic villus sampling was done (Brambati’s method). Tissue procured was then processed for direct karyotyping and studied. Metaphase spreads were photographed and karyotypes prepared and studied.
Out of 37 pregnant females, 30 samples were successfully prepared and processed by Direct method out of which 23 were normal female (46, XX) and 7 were normal male (46, XY). No normal anomaly was detected. Best biopsies were obtained with 8-12 weeks gestation. G Banding could not be performed as chromosome obtained were found to be resistant to banding.
To summarise chromosome preparations obtained from CVS by Direct method has advantage of providing sufficient number of suitable metaphases, foetal karyotype can be determined in few hours of sampling. No maternal cell contamination. But, Direct method is not good for diagnosing structural chromosomal aberration, although it’s fast, technically simple and reliable method and could be used as a routine procedure for first trimester foetal diagnosis in peripheral hospitals and thus can decrease load on referral centres.