Structural genome variations in individuals with childhood cancer and tumour predisposition syndromes

Previous studies have shown a high prevalence of syndromes in children with cancer. We described four patterns of co-occurring morphological abnormalities indicating new tumour predisposition syndromes. These patterns were named after their key-abnormalities: blepharophimosis (BP), epicanthal folds (EF), asymmetric lower limbs (LLA) and Sydney creases (SC) pattern. The purpose of our study was to identify structural genomic variants possibly involved in these tumour predisposition syndromes.

In 49 probands (13 from BP, nine from EF, 20 from LLA and seven from SC patterns respectively) karyotyping was performed. Copy number variation (CNV) in genomic DNA of the probands was analysed to detect microdeletions/-duplications using SNP array. FISH and quantitative-polymerase chain reaction (q-PCR) experiments were done to validate events identified by cytogenetic and CNV analysis.

Cytogenetic analysis showed an inherited inversion of chromosome 15, inv(15) (q25q26) in a proband with LLA-pattern. Evaluation of the genes at the breakpoints made it unlikely that these explained the phenotype and tumour in this patient. Eleven CNV events met our inclusion criteria; three inherited CNV events involved an oncogene. A duplication involving BCL9 was identified in a proband diagnosed with Burkitt lymphoma. A duplication involving PCM1 was identified in a proband diagnosed with pre-B-ALL. Both probands showed the EF-pattern of morphological abnormalities. A deletion involving TRA@ was identified in two probands from the BP-pattern diagnosed with rhabdomyosarcoma and pre-B-ALL respectively.

We report on structural genomic variants in paediatric cancer patients with newly recognised tumour predisposition syndromes. We identify three CNV events which we suggest to be susceptibility loci.