Germline pathogenic <i>SMARCA4</i> variants in neuroblastoma.

Abstract

Heterozygous germline pathogenic variants (GPVs) in <i>SMARCA4</i>, the gene encoding the ATP-dependent chromatin remodelling protein SMARCA4 (previously known as BRG1), predispose to several rare tumour types, including small cell carcinoma of the ovary, hypercalcaemic type, atypical teratoid and malignant rhabdoid tumour, and uterine sarcoma. The increase in germline testing of <i>SMARCA4</i> in recent years has revealed putative GPVs affecting <i>SMARCA4</i> in patients with other cancer types. Here we describe 11 patients with neuroblastoma (NBL), including 4 previously unreported cases, all of whom were found to harbour heterozygous germline variants in <i>SMARCA4</i> Median age at diagnosis was 5 years (range 2 months-26 years); nine were male; and eight of nine cases had tumour location information in the adrenal gland. Eight of the germline variants were expected to result in loss of function of <i>SMARCA4</i> (large deletion, truncating and canonical splice variants), while the remaining four were missense variants. Loss of heterozygosity of the wild-type <i>SMARCA4</i> allele was found in all eight cases where somatic testing was performed, supporting the notion that SMARCA4 functions as a classic tumour suppressor. Altogether, these findings strongly suggest that NBL should be included in the spectrum of <i>SMARCA4</i>-associated tumours.