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

Abstract

An unbalanced 46,XY,der(2)del(2)(p11.2p13)inv(2)(p11.2q13) karyotype was found in a phenotypically abnormal child. A de novo interstitial deletion resulting in loss of band 2p12 was present on a chromosome 2 with an inv(2)(p11.2q13) inherited from the father. The inv(2) is generally considered a benign familial variant without significant reproductive consequences. However, our findings led us to consider a previously proposed mechanism of unequal meiotic crossing over at the base of a parental inversion loop, which could lead to either duplication or deletion of a segment adjacent to the inverted region in offspring. This phenomenon has been reported in association with inversions of chromosomes 7, 13, 15 and 17 and may explain origin of the deletion in our case. Alternatively, repetitive sequences might be present around such inversions which could predispose to de novo deletions independently of the inversion.Although the mechanism of origin of the deletion in our proband cannot be proven, our review of similar imbalances with other inversions and the findings in the family described in this report suggest there could be a small risk for a related imbalance in offspring of couples with an inv(2)(p11q13). Further monitoring of pregnancy outcome in families with the inversion should be considered. However, at this point, it seems premature to recommend prenatal diagnosis for all couples in this situation.For del(2)(p11.2p13), which is rare, an emerging phenotype is proposed. Our patient shared several features with four previously published cases, namely a broad nasal bridge, abnormal ears, highly-arched palate, psychomotor retardation, and micrognathia. However, our patient also had sensorineural hearing loss and significant hypotonia which have not been previously reported.