Telomere-telomere (end to End) Fusion of Chromosomes 7 and 22 with an Interstitial Deletion of Chromosome 7p11.2-->p15.1: Phenotypic Consequences and Possible Mechanisms

We report a rare case of a de novo end to end fusion of chromosomes 7 and 22 in conjunction with an interstitial deletion of chromosome 7p11.2p15.1 in a newborn with congenital anomalies. The proband presented for chromosome analysis with bilateral cataracts, dysmorphic facies and distal limb abnormalities. Chromosome analysis showed a 45,XY,der(22)psu dic(22;7)(p13;p22.3)del(7)(p11.2p15.1) karyotype. This short arm to short arm fusion of chromosomes 7 and 22 resulted in a pseudodicentric chromosome. The interstitial deletion in the short arm of chromosome 7 was likely a result of breakage and reunion related to instability of the dicentric chromosome. Loss of genetic material in this region of chromosome 7p has been implicated in the pathophysiology of craniosynostosis and cephalopolysyndactyly syndromes.