A de novo 0.63 Mb 6q25.1 deletion associated with growth failure, congenital heart defect, underdeveloped cerebellar vermis, abnormal cutaneous elasticity and joint laxity.

ABSTRACT

Deletions of the long arm of chromosome 6 are rare and are characterized by great clinical variability according to the deletion breakpoint. We report a on 6-year-old girl with a de novo 0.63 Mb deletion on chromosome 6q25.1 who demonstrated multiple congenital anomalies including a ventricular septal defect and an underdeveloped cerebellar vermis. She presented with severe pre- and post-natal growth failure, hyperextensible small joints (Beighton scores = 8/9; with normal parental scores), and an abnormally elastic, redundant skin. Abnormally high upper/lower segment ratio (i.e., 1.34 = > 3SD), mild dysmorphic facial features and developmental delay were also present. The girl's phenotype was compared with (i) two girls, each previously reported by Bisgaard et al. and Caselli et al. with similar albeit larger (2.6-7.21 Mb) deletions; (ii) seven additional individuals (6 M; 1 F) harboring deletions within the 6q25.1 region reported in the literature; and (iii) ten further patients (5 M; 4 F; 1 unrecorded sex) recorded in the DECIPHER 6.0 database. We reported on the present girl as her findings could contribute to advance the phenotype of 6q deletions. In addition, the present deletion is the smallest so far recorded in the 6q25 region encompassing eight known genes [vs. 41 of Bisgaard et al., and 23 of Caselli et al.,], including the TAB2 (likely responsible for the girl's congenital heart defect), LATS1 gene, and the UST gene (a regulator of the homeostasis of proteoglycans, which could have played a role in the abnormal dermal and cartilage elasticity).