Rare interstitial deletion (2)(p11.2p13) in a child with pericentric inversion (2)(p11.2q13) of paternal origin

An unbalanced 46,XY,der(2)del(2) (p11.2p13) inv(2)(p11.2q13) karyotype was found in a phenotypically abnormal child with a de novo interstitial deleti on of band 2p12 associated with an inv(2)(p11.2q13) inherited from the fath er. The inv(a) is generally considered a benign familial variant without si gnificant reproductive consequences. However, our findings led us to consid er a previously proposed mechanism of unequal meiotic crossing over at the base of a parental inversion loop, which could lead to either a deletion or duplication of a segment adjacent to the inverted region in the offspring. This phenomenon has been reported in other inversions of chromosomes 1, 7, 13, 15, and 17 and may explain the origin of the deletion in our patient. Although repetitive sequences might be present around such inversions, whic h could predispose to de novo deletions independently of the inversion, cur rent evidence including this case favors a proposed causal relationship bet ween the parental inversion and the deletion in the child. Our review and r esults suggest there could be a small risk for a related imbalance to coupl es with an inv(2)(p11.2q13). For del(2)(p11.2p13), which is rare, a more di stinct phenotype has been proposed herein. Our patient shared several findi ngs with the three previously published cases, namely the broad nasal bridg e, abnormal ears, high-arched palate, psychomotor retardation, and microgna thia, However, our patient also had sensorineural hearing loss and signific ant hypotonia, which have not been previously reported, thereby expanding o ur understanding of this rare deletion. Published 1999 Wiley-Liss, Inc.(dag ger)