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DICER1
dicer 1, ribonuclease III
DICER1 encodes an enzyme that processes precursor RNA molecules into microRNAs, small regulatory molecules that control gene expression throughout the body. The DICER1 gene provides instructions for a protein central to microRNA biogenesis, a process that fine-tunes the activity of thousands of other genes.
DICER1 is located on the long (q) arm of chromosome 14, at band 14q32.13. Arm ratio per GRCh38 - banding schematic.
Explore chromosome 14 in the library →Overview
DICER1 encodes an endoribonuclease that serves as the primary enzyme responsible for generating functional microRNAs in human cells. MicroRNAs are short, non-coding RNA molecules that regulate gene expression by binding to messenger RNA transcripts and blocking protein production. The Dicer protein cleaves double-stranded RNA precursors into mature microRNA duplexes approximately 21-23 nucleotides in length, which are then incorporated into regulatory complexes that silence target genes.
Because microRNAs influence fundamental cellular processes including proliferation, differentiation and programmed cell death, disruption of DICER1 function can have wide-ranging consequences. Germline pathogenic variants in DICER1 are inherited in an autosomal dominant manner and predispose individuals to a spectrum of benign and malignant tumours collectively termed DICER1 syndrome. The gene is included in the American College of Medical Genetics and Genomics secondary findings recommendations, reflecting its clinical actionability when identified incidentally during genome or exome sequencing.
What the gene does
The Dicer protein functions as a multi-domain ribonuclease that occupies a critical node in the microRNA maturation pathway. In the cytoplasm, Dicer recognises precursor microRNA molecules exported from the nucleus and uses its tandem RNase III catalytic domains to cleave both strands of the double-stranded RNA stem, releasing a short duplex. This duplex is subsequently loaded into the RNA-induced silencing complex, where one strand serves as a guide to identify complementary sequences in messenger RNA transcripts.
Dicer collaborates with partner proteins including TARBP2 and PRKRA, which bind to a central region of the Dicer polypeptide and enhance substrate recognition and processing efficiency. Located near the C-terminus, the PAZ domain binds to the 3' overhang characteristic of precursor molecules, thereby orienting the substrate so that cleavage sites align correctly with both RNase III catalytic centres. The helicase-like domains at the N-terminus, although lacking conventional ATP-dependent helicase activity, contribute to substrate binding and may facilitate conformational changes during catalysis.
Through its role in generating hundreds of distinct microRNAs, Dicer indirectly regulates a substantial fraction of the human transcriptome. Individual microRNAs can each target dozens to hundreds of messenger RNAs, creating layered regulatory networks that govern processes from embryonic development to immune responses. Disruption of Dicer activity therefore affects not a single pathway but rather the fine-tuning of gene expression across many cellular contexts.
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Chromosome location
DICER1 is located on the long arm of chromosome 14 at band 14q32.13. This chromosomal region contains a cluster of genes involved in RNA processing and tumour suppression. The gene spans a substantial genomic interval and encodes a messenger RNA transcript that is translated into a protein of 1,922 amino acids.
Protein structure
The Dicer protein is organised into several functionally distinct domains that together enable its role in microRNA biogenesis. The N-terminal region contains a Helicase ATP-binding domain spanning amino acids 51-227, which includes the conserved DECH box motif at positions 175-178. Although this region resembles helicase domains found in other proteins, Dicer does not exhibit robust ATP-dependent unwinding activity under physiological conditions. Adjacent to this is the Helicase C-terminal domain covering amino acids 433-602, separated by a disordered region from amino acids 409-433.
A central portion of the polypeptide, extending from amino acids 256-595, is required for interaction with the accessory proteins PRKRA and TARBP2, which stabilise Dicer and modulate its substrate selectivity. Downstream lies the Dicer dsRNA-binding fold, a specialised domain spanning amino acids 630-722 that contributes to recognition of double-stranded RNA substrates.
The PAZ domain, located at amino acids 895-1,042, is a hallmark feature of proteins in the RNase III family and binds the characteristic 3' overhang of precursor microRNA molecules. The catalytic core comprises two tandem RNase III domains: RNase III 1 at amino acids 1,276-1,403 and RNase III 2 at amino acids 1,666-1,824. These two RNase III regions associate to generate a structure with dual catalytic centres, with each centre cutting one strand of the duplex RNA substrate. Finally, a double-stranded RNA-binding motif (DRBM) occupies the C-terminal region from amino acids 1,849-1,914, further anchoring substrates during processing.
Key variants
Pathogenic variants in DICER1 predominantly fall into two functional categories. Germline variants that cause DICER1 syndrome are typically loss-of-function changes distributed throughout the gene, resulting in haploinsufficiency of Dicer activity. These include nonsense mutations, frameshift insertions or deletions, and splice-site alterations that lead to premature truncation of the protein. A subset of germline variants affects the RNase III domains and may partially impair catalytic function.
Somatic variants in tumours from individuals with DICER1 syndrome frequently occur as second hits in the RNase IIIb domain, particularly at positions critical for enzymatic activity. These recurrent hotspot mutations further reduce microRNA processing capacity in tumour cells. The combination of a germline loss-of-function variant and a somatic catalytic-domain mutation is thought to create the dysregulated gene expression landscape that drives tumourigenesis in affected tissues.
Sample of pathogenic variants
10 pathogenic / likely-pathogenic variants from ClinVar, ranked by review status (expert-panel-reviewed first). This is a sample; recurrent founder variants in a specific population may not appear here - see the full ClinVar listing via the link above.
| Variant (HGVS) | Protein change | Classification | Evidence | Associated condition |
|---|---|---|---|---|
c.1408G>T | p.Glu470Ter | Pathogenic | ★★★☆ | DICER1-related tumor predisposition |
c.1880_1883del | p.Ile627fs | Pathogenic | ★★★☆ | DICER1-related tumor predisposition |
c.1907+1G>A | - | Pathogenic | ★★★☆ | Hereditary cancer-predisposing syndrome |
c.2524del | p.Met842fs | Pathogenic | ★★★☆ | not provided |
c.2650+1G>T | - | Pathogenic | ★★★☆ | DICER1-related tumor predisposition |
c.2988-1G>T | - | Pathogenic | ★★★☆ | Hereditary cancer-predisposing syndrome |
c.3019C>T | p.Gln1007Ter | Pathogenic | ★★★☆ | Hereditary cancer-predisposing syndrome |
c.5096-12G>A | - | Pathogenic | ★★★☆ | DICER1-related tumor predisposition |
c.5104C>T | p.Gln1702Ter | Pathogenic | ★★★☆ | DICER1-related tumor predisposition |
c.5113G>A | p.Glu1705Lys | Pathogenic | ★★★☆ | DICER1-related tumor predisposition |
Evidence stars indicate ClinVar review status. Individual variant interpretation should always be performed by a qualified clinical laboratory - many variants remain classified as Variants of Uncertain Significance (VUS) pending more research.
Associated conditions
Germline pathogenic variants in DICER1 cause DICER1 syndrome, an autosomal dominant tumour predisposition condition with variable expressivity and age-dependent penetrance. Affected individuals face elevated risk for a characteristic spectrum of neoplasms, many of which are rare in the general population. Pleuropulmonary blastoma, a malignant lung tumour of early childhood, is strongly associated with DICER1 syndrome and may present in infancy or early childhood. Cystic nephroma, a benign kidney tumour, occurs with increased frequency in children carrying pathogenic DICER1 variants.
Ovarian Sertoli-Leydig cell tumours, rare sex cord-stromal neoplasms that typically arise in adolescence or young adulthood, are observed at higher rates in females with DICER1 syndrome. Thyroid abnormalities have been reported in individuals with DICER1 syndrome. Not all individuals with a pathogenic DICER1 variant will develop tumours, and the specific tumour types and age of onset vary widely even within families.
Inheritance pattern
Conditions caused by pathogenic DICER1 variants typically follow autosomal dominant inheritance.
Each child has a 50% chance of inheriting the pathogenic variant, regardless of sex.
UK clinical status
DICER1 appears on multiple NHS Genomic Medicine Service gene panels, reflecting its clinical relevance across paediatric and adult oncology. The gene holds green (high-evidence) status on the Adult solid tumours cancer susceptibility panel and the Adult solid tumours for rare disease panel, as well as the Childhood solid tumours and Childhood solid tumours cancer susceptibility panels. DICER1 is also listed on the DICER1-related cancer predisposition panel (R364) and the Embryonal tumour of possible germline origin panel (R456), both with green classification.
Additional green-rated memberships include the Inherited non-medullary thyroid cancer panel and the Sarcoma of possible germline origin panel (R457). The gene is also present on the COVID-19 research panel, though the clinical significance in that context is less well established. These panel inclusions indicate that pathogenic DICER1 variants identified through NHS genomic testing may prompt surveillance protocols and referral to specialist multidisciplinary teams for cancer risk management.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Diet & lifestyle considerations
Research into lifestyle factors that might modify tumour risk in individuals with DICER1 syndrome remains limited. General cancer prevention strategies, such as avoiding tobacco smoke and maintaining a healthy body weight, are considered reasonable for the broader population, though no evidence specifically links these measures to reduced DICER1-related tumour incidence. Some clinical guidelines recommend imaging surveillance for at-risk organs in individuals known to carry pathogenic DICER1 variants, enabling earlier detection of treatable lesions.
Because DICER1 syndrome can present with thyroid abnormalities, some healthcare providers monitor thyroid function in affected individuals. There is no established dietary intervention shown to prevent DICER1-related tumours, and families should be cautious of unverified claims regarding specific foods or nutritional regimens. Any lifestyle modification or surveillance programme should be discussed with a clinical genetics service or oncology team familiar with hereditary tumour syndromes.
Supplement considerations
No dietary supplements have been demonstrated to reduce tumour risk in individuals with pathogenic DICER1 variants. Micronutrient sufficiency is important for general health, but there is no conclusive evidence that vitamin or mineral supplementation prevents the development of DICER1-related neoplasms. Some commercially available products claim to support RNA processing or cellular detoxification pathways, but these assertions are not supported by peer-reviewed clinical trials in the context of DICER1 syndrome.
Individuals considering any supplement should consult a healthcare provider before use, particularly if undergoing active cancer treatment, as certain compounds may interact with chemotherapy agents or other medications. A balanced diet that meets general nutritional requirements is appropriate for most individuals, with or without DICER1 variants, and should be prioritised over unproven supplementation regimens.
Frequently asked questions
What is DICER1 syndrome?
DICER1 syndrome is an autosomal dominant condition caused by pathogenic variants in the DICER1 gene, characterised by increased risk of specific benign and malignant tumours. Affected individuals may develop pleuropulmonary blastoma, cystic nephroma, ovarian Sertoli-Leydig cell tumours and other rare neoplasms, with variable age of onset and penetrance.
How is DICER1 inherited?
DICER1 syndrome follows an autosomal dominant inheritance pattern, meaning a single pathogenic variant inherited from one parent is sufficient to confer increased tumour risk. Each child of an affected parent has a 50 per cent chance of inheriting the variant, though not all carriers will develop tumours.
What does the Dicer protein do?
The Dicer protein cleaves precursor RNA molecules to produce mature microRNAs, short regulatory molecules that control gene expression by blocking protein production. Through this role, Dicer influences cell growth, differentiation and many other fundamental processes.
Are there surveillance recommendations for DICER1 variant carriers?
Some clinical guidelines recommend imaging surveillance of the lungs, kidneys and thyroid in individuals with pathogenic DICER1 variants, particularly during childhood, to enable early detection of tumours. Surveillance protocols should be tailored to individual and family history and discussed with a clinical genetics or oncology team.
Can lifestyle changes reduce tumour risk in DICER1 syndrome?
No specific lifestyle interventions have been proven to reduce DICER1-related tumour risk. General cancer prevention measures such as avoiding tobacco and maintaining healthy weight are sensible for overall health, but evidence linking these to DICER1 syndrome outcomes is lacking. Surveillance and early detection remain the primary risk-management strategies.
References
- Rio Frio T, Bahubeshi A, Kanellopoulou C. DICER1 mutations in familial multinodular goiter with and without ovarian Sertoli-Leydig cell tumors. JAMA. 2011. PMID: 21205968
- Slade I, Bacchelli C, Davies H. DICER1 syndrome: clarifying the diagnosis, clinical features and management implications of a pleiotropic tumour predisposition syndrome. Journal of medical genetics. 2011. PMID: 21266384
- Schultz KA, Pacheco MC, Yang J. Ovarian sex cord-stromal tumors, pleuropulmonary blastoma and DICER1 mutations: a report from the International Pleuropulmonary Blastoma Registry. Gynecologic oncology. 2011. PMID: 21501861
- Bahubeshi A, Bal N, Rio Frio T. Germline DICER1 mutations and familial cystic nephroma. Journal of medical genetics. 2010. PMID: 21036787
- Ghildiyal M, Zamore PD. Small silencing RNAs: an expanding universe. Nature reviews. Genetics. 2009. PMID: 19148191
- Carthew RW, Sontheimer EJ. Origins and Mechanisms of miRNAs and siRNAs. Cell. 2009. PMID: 19239886