Chromosome abnormalities and pregnancy losses

Cytogenetics Investigations

Chromosome abnormalities – The overall prevalence of pregnancy losses, including biochemical pregnancies is generally assumed to be 4–5 times higher. Around a quarter of all women experience at least one miscarriage during their lives.

Half of the first-trimester miscarriages are caused by fetal chromosome abnormalities diagnosed by conventional techniques. Conventional karyotyping is defined as the morphological characterization of the chromosomal complement of an individual including number, form and size of the chromosomes. It can detect abnormalities throughout the entire genome and is therefore used as the standard for detecting abnormalities in miscarriages samples

A review of the literature in 2000 reported that 49% of the sporadic miscarriage samples that had been karyotyped, showed chromosome abnormalities. The spectrum of these abnormalities included 86% numerical abnormalities, 6% structural abnormalities and 8% other chromosome abnormalities like mosaicism, or double and triple trisomies.

Techniques such as chromosomal comparative genomic hybridization (chromosomal‐CGH), array-comparative genomic hybridization (array-CGH), fluorescence in situ hybridization FISH, multiplex ligation-dependent probe amplification (MLPA) and quantitative fluorescent polymerase chain reaction (QF-PCR) enable us to trace submicroscopic abnormalities.

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