Abstract
Reciprocal chromosomal rearrangements, de novo or inherited, often raise a concern
about the foetal health and outcome of the affected pregnancies. The size and origin
of the translocated chromosomes could be variable. Cryptic translocations often remain
undetected and misdiagnosed. Several studies confirmed that there could be a loss
of a certain amount of genomic material within breakpoints, which leads to uncertainties
in predicting the pregnancy outcome. A 38 year pregnant woman approached our clinic
for a genetic counselling. This was her first pregnancy, with normal foetal growth
on ultrasound follow up. The amniocentesis was carried out due to the advanced maternal
age. Conventional cytogenetic report showed putative deletion of short arm of chromosome
5. Cordocentesis was done additionally at 18 week of pregnancy due to the discrepancy
between normal ultrasonographic finding and karyotype result. MLPA analysis showed
that 5p critical region was present. FISH has been performed, using 5p;q probe (Cytocell
aquarius, Cat No LPU 013), which showed cryptic de novo translocation 46,XX.ish t(5;17)
(p15.1;q25). Decision to terminate the pregnancy was made due to the cytogenetic finding
and reduced foetal growth recorded after 20th week. Examination at autopsy showed
dysmorphism consistent with some features of cri du chat syndrome-micrognathia, hypertelorism,
reduced fetal growth, as well as underdeveloped brain for gestational period. Novel
technologies in molecular cytogenetics and array techniques could help in detecting
minor imbalances and decrease the risk of the birth of malformed fetus. Combination
of several prenatal methods -both ultrasonography and novel genetic techniques, in
a small number of cases can help in the process of genetic counselling.
Keywords
Prenatal diagnosis - Cryptic translocation - Fluorescent in situ hybridisation - Cri
du chat syndrome - Foetal dysmorphology
