The molecular mechanisms leading to mcROBs formation are still not well known, except the observation that they mainly arise during oogenesis (Shaffer 2002). It is possible that sequences found on chromosomes 13, 14, and 21 mediate homologous recombination resulting in these translocations. Moreover, it was postulated that the order of sequences in 14p are in opposite orientation than topography of homologous sequences in 13p and 21p