Inv dup(22), del(22)(q11) and r(22) in the father of a child with DiGeorgesyndrome

We here report a unique inherited case of DiGeorge syndrome. The asymptomat ic father had a mosaic karyotype with a 21q11 deletion in three different c ell lines. In two of the cell lines there was an additional supernumerary i nv dup(22) or an r(22), respectively. In the third cell line the del(22) wa s the sole anomaly FISH analysis showed that both the inv dup(22) and the r (22) included the DGS region. We hypothesize that an inter-chromosomal reco mbination between inverted repeats, together with a recombination between s ister chromatids during meiosis I, gave rise to a deletion of 22q11 as well as an inv dup(22) containing the DCS region. The inv dup(22) was later rea rranged into a ring chromosome during mitosis which was subsequently lost d uring cell division, thereby resulting in three different cell lines. This is the first case reported with an inv dup(22) and a del(22)(q11) in the sa me cell line. Our findings support a related mechanism in the formation of these two rearrangements mediated by low-copy repeats.