Complex phenotype and development of an atypical rhabdoid tumour in a boy with a 46,XY,inv(22)(p11.2q12.3).ish inv(22)(WCP22+,TUPLE1+,BCR-,EWS+,MS607+)
We present a patient with multiple congenital anomalies, dysmorphism, and developmental delay. He had complex congenital heart disease (double outlet right ventricle, hypoplastic left ventricle, sub pulmonary stenosis and patent ductus arteriosus), an absent left kidney, an abnormal left testis and bilateral corneal anaesthesia. Chromosome analysis initially demonstrated the presence of a de novo apparently balanced pericentric inversion of one chromosome 22 involving breakpoints p11.2 and q12.3. FISH studies using whole chromosome painting and TUPLE1 probe showed that the inverted chromosome was all chromosome 22 and TUPLE1 (the DiGeorge critical region) was intact.
At the age of 14 months he was diagnosed with a left hemispheric tumour which was confirmed to be an atypical teratoid rhabdoid tumour. Given his phenotype, the karyotype was reviewed and further FISH tests were performed. FISH studies using the 22q subtelomere probe (BCR region as control) and the EWS (Ewings sarcoma critical region -22q12) showed the presence of the subtelomere but deletion of the BCR locus. CGH and gene mapping were carried out to ascertain the extent of the deletion. CGH studies were non-informative but gene mapping using 16 markers confirmed deletion of genes BCR and 80O7 and inversion of genes proximal to q13.1. The size of the deletion is between 0.9-1.8Mb. The final karyotype after FISH studies and molecular testing was reported as 46,XY,inv(22)(p11.2q12.3).ish inv(22)(WCP22+,TUPLE1+,BCR-,EWS+,MS607+).
We discuss the cytogenetic finding in relation to his phenotype and the development of his tumour.