Broadening our understanding by the use of molecular cytogenetic techniques: full monosomy 21

Multiple risk factors such as exposure to teratogens, advanced parental age, anatomic anomalies of the mother, genetic diseases and chromosomal anomalies are involved in embryo loss. Spontaneous abortions occur in approximately 10–15% of clinically recognised pregnancies. Most women who miscarry are not informed of the cause of their pregnancy loss, thereby causing them anxiety, confusion, low self-esteem and depression [1, 2]. Knowledge of the causes of spontaneous abortion reduces both stress and the feeling of culpability that occur after miscarriage [1]. Cytogenetic advances in the understanding and detection of human chromosomal rearrangements related to certain diseases have allowed for diagnosis of most cases of miscarriage. According to the literature, some 65% of first-trimester spontaneous abortions have been shown to carry chromosomal anomalies [3], although this figure may be below the actual percentage due to culture failure since karyotyping cannot be performed on such cases [4]. Therefore, it is likely that advanced molecular techniques such as multiplex ligation-dependent probe amplification (MLPA) would permit an increase in the percentage of chromosomal anomalies detected and even make it possible to identify other full monosomies which are involved in foetal loss. Loss of a whole chromosome may be lethal possibly because of the haploinsufficiency of essential genes. In fact, Turner syndrome (45X) is the only full monosomy that is compatible with life. Here, we report a full monosomy 21 identified by MLPA and confirmed by array CGH in a molecular study of 310 miscarriages. Full monosomy 21 (FM21) is a very rare chromosomal anomaly and one of the few cases that have appeared in the literature to date is the first full monosomy 21 observed in Spain published by Mori MA et al in 2004 [5].