A novel unusual chromosome 11 abnormality: a homozygous somatic deletion of the entire WT1 gene within a heterozygous 11p13 deletion and UPD limited to 11p15 in a Wilms tumor and establishment of an immortalized cell line

We describe a stromal predominant Wilms tumor with a complex, tumor specific chromosome 11 aberration: a homozygous deletion of the entire WT1 gene within a heterozygous 11p13 deletion and an additional region of uniparental disomy (UPD) limited to 11p15.5-p15.2 including the IGF2 gene. The tumor carried a heterozygous p.T41A mutation in CTNNB1. Cells established from the tumor carried the same chromosome 11 aberration, but a different, homozygous p.S45Δ CTNNB1 mutation. Uniparental disomy (UPD) 3p21.3pter lead to the homozygous CTNNB1 mutation. The tumor cell line was immortalized with telomerase (TERT) and a novel triple ts mutant SV40 large T antigen (LT). This cell line is cytogenetically stable and can be grown indefinitely. It is a valuable tool to study the effect of a complete lack of WT1 in tumor cells. The tumor cell line and the immortalized cells have a limited potential for muscle/osteogenic/adipogenic differentiation similar to all other WT1 mutant cell lines. Array expression experiment of Wilms tumor cell lines