Double Interstitial Deletion of the Long Arm of Chromosome 6 in a Patient with Pierre Robin Sequence, Dysmorphisms, and Severe Developmental Delay

Abstract

Reported here is the case of a 1.8-year-old boy with a 9.6- Mb deletion in 6q13q14.1 and an 11.2-Mb deletion in 6q21q22.31, ascertained through array CGH, as the result of a complex de novo chromosome rearrangement. The clinical picture of this patient is characterized by severe psychomotor delay, dysmorphic features, and some congenital defects. Although, as reported in the literature, phenotypes associated with 6q deletions may vary, an attempt was made to associate the patient's symptoms to either deletion, comparing them to previously reported cases. Only a limited specific correlation was found, probably due to the prevalence of very common symptoms.

Keywords: Array comparative genomic hybridization; Congenital defects; Microdeletion 6q; Psychomotor delay.

Fig. 1.

Facial features of the patient at birth (A) showing hypoplastic superciliary arches, sparse eyebrows, asymmetric simple and low-set ears, long and smooth philtrum, thin upper and lower lip as well as microretrognathia. Photographs of the patient at 20 months (B-E). B Frontal view: hypoplastic superciliary arches, sparse eyebrows, upslanting palpebral fissures, bilateral epicanthus and strabismus, telecanthus, asymmetric simple and low-set ears, long and smooth philtrum, thin upper and lower lip, and microretrognathia. C Left ear: simple and low-set ear. D Hands: postaxial polydactyly (without syndactyly) of the left hand. E Feet: postaxial polydactyly (without syndactyly) of both feet.

Fig. 2.

A Patient's karyotype showing 2 interstitial deletions in the long arm of chromosome 6 and a reciprocal translocation between chromosomes 1 and 4. The arrows indicate the breakpoints in the chromosomes involved in the translocation (red arrow on chromosome 1 and yellow arrow on chromosome 4). By FISH (not shown), 2 insertional translocations from chromosome 6 to chromosomes 1 and 15 were detected (green arrows indicate the insertion regions on the derivative chromosomes). B, C Array-CGH profile of chromosome 6 showing the 2 deletions in chromosome 6 as generated by CytoChip (BluGnome LTD). The breakpoint of the 6q13q14.1 deletion is from position 73,452,121 to 83,053,393 bp. The size of the deletion is about 9.6 Mb (B). The breakpoint of the 6q21q22.31 deletion is from position 112,795,067 to 124,005,614 bp. The size of the deletion is about 11.2 Mb (C). D Schematic representation of the 6q13q14.1 and the 6q21q22.31 regions and of the deletions identified in our patient and in patients described in the literature. The size of the deletions, reported by the different authors, was converted, if necessary, in the hg19 assembly.