Maternal origin of monosomy 21 derived from ICSI

With the worldwide diffusion of the intracytoplasmic sperm injection (ICSI) procedure in recent years, the issue of possible genetic risks of this new and powerful technique has attracted considerable attention. An important concern is whether ICSI facilitated the passage of genetic defects from spermatozoa to offspring. ICSI was performed with spermatozoa from a frozen-thawed sperm sample from a testicular sperm extraction (TESE) of a 38 year old man who suffered from azoospermia. His wife was 36 years old. The resulting pregnancy spontaneously aborted at 8 weeks gestation after embryo replacement. Cytogenetic investigation displayed monosomy 21. The paternal origin of the single chromosome 21 was determined by molecular analysis. The segregation error leading to loss of one chromosome 21 is likely to have occurred during oogenesis rather than as a direct consequence of ICSI. Nonetheless, monosomy 21 is extremely rare and it cannot be excluded that ICSI assisted the fertilization of an abnormal oocyte.