AIM OF STUDY: An analysis of prenatal diagnostics efficiency of selected types 
of chromosomal aberrations in the Czech Republic in 2007. Update of 1994-2007 
data according to particular selected diagnoses.
TYPE OF STUDY: Retrospective epidemiological analysis of pre- and postnatal 
chromosomal aberrations diagnostics and its efficiency.
MATERIAL AND METHODS: Data on pre- and postnatally diagnosed birth defects in 
the Czech Republic during 1994-2007 were used. Data on prenatally diagnosed 
birth defects (and for terminated pregnancies) were collected from particular 
departments of prenatal diagnostics, medical genetics and ultrasound diagnostics 
in the Czech Republic, data on birth defects in births from the National Birth 
Defects Register (Institute for Health Information and Statistics). Total 
numbers over the period under the study, mean incidences of selected types of 
chromosomal aberrations and mean prenatal diagnostics efficiencies were 
analyzed. Following chromosomal aberrations were studied: Down, Edwards, Patau, 
Turner and Klinefelter syndromes and syndromes 47,XXX and 47,XYY.
RESULTS: A relative proportion of Down, Edwards and Patau syndromes as well as 
other autosomal and gonosomal aberration is presented in figures. Recently, 
trisomies 13, 18 and 21 present around 70% of all chromosomal aberrations in 
selectively aborted fetuses, in other pregnancies, "other chromosomal 
aberrations" category (mostly balanced reciprocal translocations and inversions) 
present more than 2/3 of all diagnoses. During the period under the study, 
following total numbers, mean relative incidences (per 10,000 live births, in 
brackets) and mean prenatal diagnostics efficiency (in %) were found in 
following chromosomal syndromes: Down syndrome 2,244 (16.58) and 63.37%, Edwards 
syndrome 521 (3.85) and 79.93%, Patau syndrome 201 (1.49) and 68.87%, Turner 
syndrome 380 (2.81) and 79.89%, 47,XXX syndrome 61 (0.45) and 59.74%, 
Klinefelter syndrome 163 (1.20) and 73.65% and 47,XYY syndrome 22 (0.16) and 
54.76%.
CONCLUSIONS: The study gives updated results of incidences analysis of both pre- 
and postnatally diagnosed chromosomal birth defects in the Czech Republic during 
the 1994-2007 period. Incidences found in our study correspond (in case of 
trisomies 13, 18 and 21) with those published widely in literature as well as 
with those found in large-scale international studies (ICBDSR, EUROCAT). In case 
of gonosomal aberrations, incidences found in this study are lower that those 
published, most probably due to a later registration (over 15 years of age of 
the child) of these diagnoses.