A familial Cri-du-Chat/5p deletion syndrome resulted from rare maternal complex chromosomal rearrangements (CCRs) and/or possible chromosome 5p chromothripsis.

Abstract

Cri-du-Chat syndrome (MIM 123450) is a chromosomal syndrome characterized by the characteristic features, including cat-like cry and chromosome 5p deletions. We report a family with five individuals showing chromosomal rearrangements involving 5p, resulting from rare maternal complex chromosomal rearrangements (CCRs), diagnosed post- and pre-natally by comprehensive molecular and cytogenetic analyses. Two probands, including a 4½-year-old brother and his 2½-year- old sister, showed no diagnostic cat cry during infancy, but presented with developmental delay, dysmorphic and autistic features. Both patients had an interstitial deletion del(5)(p13.3p15.33) spanning ≈ 26.22 Mb. The phenotypically normal mother had de novo CCRs involving 11 breakpoints and three chromosomes: ins(11;5) (q23;p14.1p15.31),ins(21;5)(q21;p13.3p14.1),ins(21;5)(q21;p15.31p15.33),inv(7)(p22q32)dn. In addition to these two children, she had three first-trimester miscarriages, two terminations due to the identification of the 5p deletion and one delivery of a phenotypically normal daughter. The unaffected daughter had the maternal ins(11;5) identified prenatally and an identical maternal allele haplotype of 5p. Array CGH did not detect any copy number changes in the mother, and revealed three interstitial deletions within 5p15.33-p13.3, in the unaffected daughter, likely products of the maternal insertions ins(21;5). Chromothripsis has been recently reported as a mechanism drives germline CCRs in pediatric patients with congenital defects. We postulate that the unique CCRs in the phenotypically normal mother could resulted from chromosome 5p chromothripsis, that further resulted in the interstitial 5p deletions in the unaffected daughter. Further high resolution sequencing based analysis is needed to determine whether chromothripsis is also present as a germline structural variation in phenotypically normal individuals in this family.