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HNF4A
hepatocyte nuclear factor 4 alpha
The HNF4A gene provides instructions for producing the Hepatocyte Nuclear Factor 4 Alpha protein, a key transcription factor involved in regulating gene expression vital for pancreatic beta cell function and liver metabolism. HNF4A is central to the proper development and function of the pancreas and liver by controlling genes involved in insulin production and glucose regulation.
HNF4A is located on the long (q) arm of chromosome 20, at band 20q13.12. Arm ratio per GRCh38 - banding schematic.
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Overview
The HNF4A gene encodes Hepatocyte Nuclear Factor 4 Alpha (HNF-4α), a protein that functions as a transcription factor. This protein plays a critical role in regulating the activity of specific genes, particularly those important for the normal function of pancreatic beta cells and the liver. Proper HNF-4α activity is essential for maintaining blood sugar balance and overall metabolic health.
What the gene does
HNF-4α acts as a transcription factor, meaning it binds to particular DNA regions to control gene expression. It is crucial for the development and function of pancreatic beta cells, which are responsible for producing and secreting insulin. Insulin is a hormone vital for regulating blood glucose levels by facilitating glucose uptake into cells for energy. HNF-4α also regulates genes involved in various normal liver functions, contributing to metabolic homeostasis. The protein operates by forming a dimer, a unit of two HNF-4α molecules, which then binds to DNA to exert its regulatory effects.
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Chromosome location
The HNF4A gene is located on chromosome 20 at position 20q13.12. This specific genomic location places the gene in a region of the genome known to harbour genes involved in various metabolic processes.
Protein structure
The HNF-4α protein is composed of 474 amino acids and features several distinct functional domains. It includes a Nuclear receptor (DNA binding) domain spanning amino acids 57-132, which is essential for its role as a transcription factor. Within this DNA binding region are two NR C4-type (Zinc finger) domains, located at amino acids 60-80 and 96-120. A significant NR LBD (Domain), referring to the Ligand Binding Domain, is found between amino acids 147-377. Additionally, a 9aaTAD (Motif) is present at amino acids 368-376, and a Disordered (Region) is identified between amino acids 419-447.
Key variants
Variants within the HNF4A gene can lead to changes in the structure or function of the HNF-4α protein. Such changes can impair its ability to regulate gene expression, particularly those genes crucial for glucose metabolism. The spectrum of variants can range from single nucleotide changes to larger deletions or insertions, each with potential implications for protein function.
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.1000C>T | p.Gln334Ter | Pathogenic | ★★★☆ | Monogenic diabetes |
c.1045C>T | p.Gln349Ter | Pathogenic | ★★★☆ | Monogenic diabetes |
c.1256C>G | p.Ser419Ter | Pathogenic | ★★★☆ | Monogenic diabetes |
c.145C>T | p.His49Tyr | Pathogenic | ★★★☆ | Monogenic diabetes |
c.152dup | p.Ala52fs | Pathogenic | ★★★☆ | Monogenic diabetes |
c.-181G>A | - | Pathogenic | ★★★☆ | Maturity-onset diabetes of the young type 1 |
c.185del | p.Phe62fs | Pathogenic | ★★★☆ | Monogenic diabetes |
c.187C>T | p.Arg63Trp | Pathogenic | ★★★☆ | Fanconi renotubular syndrome 4 with maturity-onset diabetes of the young |
c.188G>A | p.Arg63Gln | Pathogenic | ★★★☆ | not provided |
c.199C>T | p.Arg67Trp | Pathogenic | ★★★☆ | not provided |
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
Pathogenic variants in the HNF4A gene are primarily associated with Maturity-Onset Diabetes of the Young, type 1 (MODY1). This form of diabetes typically manifests before the age of 30 and is characterised by high blood sugar levels. Individuals with MODY1 due to HNF4A variants may also experience congenital hyperinsulinism, leading to unusually low blood sugar levels at birth, often alongside being larger than average at birth.
Inheritance pattern
Conditions caused by pathogenic HNF4A variants typically follow autosomal dominant inheritance.
Each child has a 50% chance of inheriting the pathogenic variant, regardless of sex.
UK clinical status
HNF4A is recognised in the UK National Health Service (NHS) Genomic Medicine Service. It is listed on several NHS Genomic Test Directory panels, including 'Congenital hyperinsulinism', 'DDG2P', 'Diabetes with additional phenotypes suggestive of a monogenic aetiology', 'Familial diabetes', 'Foetal anomalies', 'Monogenic diabetes', 'Nephrocalcinosis or nephrolithiasis', and 'Renal tubulopathies'. This indicates its importance in the diagnosis and management of related conditions within the UK healthcare system.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Frequently asked questions
What is the main role of the HNF4A gene?
The HNF4A gene is critical for making a protein called Hepatocyte Nuclear Factor 4 Alpha (HNF-4α), which acts as a transcription factor. It controls the activity of genes important for the function of pancreatic beta cells, responsible for insulin production, and for liver functions that manage blood sugar.
What health condition is linked to HNF4A?
Variants in the HNF4A gene are primarily linked to Maturity-Onset Diabetes of the Young, type 1 (MODY1). This condition typically causes high blood sugar levels from a young age and can also be associated with congenital hyperinsulinism in newborns.
How does HNF-4α affect blood sugar?
HNF-4α influences blood sugar by regulating genes involved in insulin production and secretion from pancreatic beta cells. Insulin helps move sugar from the bloodstream into cells, so proper HNF-4α function is essential for maintaining balanced blood glucose levels.
References
- Singh P, Tung SP, Han EH. Dimerization defective MODY mutations of hepatocyte nuclear factor 4α. Mutation research. 2019. PMID: 30648609
- Yamagata K. Roles of HNF1α and HNF4α in pancreatic β-cells: lessons from a monogenic form of diabetes (MODY). Vitamins and hormones. 2014. PMID: 24559927
- Rha GB, Wu G, Chi YI. Probing the effect of MODY mutations near the co-activator-binding pocket of HNF4α. Bioscience reports. 2011. PMID: 21323639