Germline Pathogenic DROSHA Variants Are Linked to Pineoblastoma and Wilms Tumor Predisposition

Abstract

Purpose: DROSHA, DGCR8, and DICER1 regulate miRNA biogenesis and are commonly mutated in cancer. Although DGCR8 and DICER1 germline pathogenic variants (GPV) cause autosomal dominant tumor predisposition, no association between DROSHA GPVs and clinical phenotypes has been reported.

Experimental design: After obtaining informed consent, sequencing was performed on germline and tumor samples from all patients. The occurrence of germline DROSHA GPVs was investigated in large pediatric and adult cancer datasets. The population prevalence of DROSHA GPVs was investigated in the UK Biobank and Geisinger DiscovEHR cohorts.

Results: We describe nine children from eight families with heterozygous DROSHA GPVs and a diagnosis of pineoblastoma (n = 8) or Wilms tumor (n = 1). A somatic second hit in DROSHA was detected in all eight tumors analyzed. All pineoblastoma tumors analyzed were classified as miRNA processing-altered 1 subtype. We estimate the population prevalence of germline DROSHA loss-of-function variants to be 1:3,875 to 1:4,843 but find no evidence for increased adult cancer risk.

Conclusions: This is the first report of DROSHA-related tumor predisposition. As pineoblastoma and Wilms tumor are also associated with DICER1 GPVs, our results suggest that the tissues of origin for these tumors are uniquely tolerant of general miRNA loss. The miRNA processing-altered 1 pineoblastoma subtype is associated with older age of diagnosis and better outcomes than other subtypes, suggesting DROSHA GPV status may have important clinical and prognostic significance. We suggest that genetic testing for DROSHA GPVs be considered for patients with pineoblastoma, Wilms tumor, or other DICER1-/DGCR8-related conditions and propose surveillance recommendations through research studies for individuals with DROSHA GPVs.

Figure 1.

Family 1 pedigree. Individuals with pineoblastoma are shaded in dark blue. Other cancer-affected family members are shaded in light blue. WES was performed on germline DNA isolated from both probands and their mothers who are full biological sisters but cancer-unaffected, as well as the tumor DNA from individual II-1.

Figure 2.

Map of the DROSHA protein showing functional domains and sites of germline and somatic pathogenic variants identified in families 1 to 8. dsRBD, double-stranded RNA-binding domain; P-rich, proline-rich; RIIIDb, RNase III domain B; RS-rich, arginine/serine-rich.

Figure 3.

Representative WES alignment sequence reads from individual II-1 (family 1). p.R271Ter is found on one allele of DROSHA in the patient’s germline and tumor samples. Y265Ter is found in trans in the tumor, indicating biallelic loss of DROSHA in the tumor. Nucleotide cDNA sequence for DROSHA is shown in the 3′ to 5′ direction from left to right. The amino acid sequence is in C- to N-terminus direction from left to right.

Figure 4.

DROSHA Sanger sequencing chromatograms of individual 9, family 7, indicating a germline 4 bp deletion with LOH in the tumor. The plot shows the sequence results from germline (A) and pineoblastoma tumor (B) DNA. The x-axis represents the position of the sequencing read in DROSHA, and the y-axis represents the signal intensity of each potential nucleotide at that position. The color of the line represents each of the four nucleotides (adenosine: green, thymine: red, cytosine: blue, and guanosine: black). The aligned nucleotide sequence is provided above each peak in which degenerate positions are represented with International Union of Pure and Applied Chemistry codes. The position of the 4 bp deletion is represented by a light blue–highlighted region.

Figure 5.

DROSHA lollipop plot. Depiction of TCGA, population-level, and family-level DROSHA LOF variants superimposed on the domain structure of DROSHA. Variants identified from population-level queries of UKBB and Geisinger DiscovEHR are shown in blue. TCGA-identified variants are shown in green. Variants identified in the eight families are shown in pink. DRBM, Double-stranded RNA binding motif.