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HNRNPH2
heterogeneous nuclear ribonucleoprotein H2
HNRNPH2 is located on the long (q) arm of chromosome X, at band Xq22.1. Arm ratio per GRCh38 - banding schematic.
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Overview
HNRNPH2 is situated on the X chromosome at band Xq22.1 and encodes a member of the heterogeneous nuclear ribonucleoprotein (hnRNP) family. These proteins bind to RNA molecules and coordinate key steps in gene expression, particularly the processing of pre-messenger RNA into mature mRNA. The protein product, hnRNP H2, contributes to alternative splicing, a mechanism that allows a single gene to produce multiple protein variants by including or excluding specific RNA segments.
Because HNRNPH2 resides on the X chromosome, the inheritance pattern and clinical impact can differ between individuals depending on biological sex. Pathogenic variants in this gene have been identified in individuals with neurodevelopmental features, and HNRNPH2 appears on several NHS Genomic Medicine Service gene panels related to early development and neurological function.
What the gene does
The hnRNP H2 protein operates primarily within the cell nucleus, where it binds to nascent RNA transcripts and influences how these molecules are assembled into functional messenger RNAs. Through its interaction with specific RNA sequences, hnRNP H2 helps determine which exons are retained or skipped during splicing, thereby shaping the repertoire of proteins a cell can produce from its genetic instructions.
Research suggests that hnRNP H2 participates in multiple aspects of RNA metabolism beyond splicing, including the stability and localisation of RNA molecules. The protein's ability to recognise particular RNA motifs allows it to coordinate the expression of genes involved in neuronal development and synaptic function. Disruption of these regulatory processes may compromise the precise control of gene expression required during brain maturation, potentially contributing to the neurodevelopmental phenotypes observed in affected individuals. The protein's role appears especially important in tissues with high metabolic and regulatory demands, such as the developing central nervous system.
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Chromosome location
HNRNPH2 is located on the long arm of the X chromosome at cytogenetic band Xq22.1. The gene spans multiple exons, encoding a transcript that is translated into a 449-amino-acid protein. Its position on the X chromosome means that inheritance patterns follow X-linked mechanisms, where individuals with one X chromosome (typically biological males) may be more severely affected by loss-of-function variants, while those with two X chromosomes may exhibit variable expressivity depending on patterns of X-inactivation.
Protein structure
The hnRNP H2 protein comprises 449 amino acids organised into distinct functional regions. The N-terminal portion contains RRM 1 (amino acids 11-90), followed by RRM 2 (amino acids 111-188), which are RNA recognition motifs responsible for binding RNA substrates with sequence specificity. Further downstream, RRM 3 (amino acids 289-364) provides additional RNA-binding capability.
The C-terminal half of the protein features a glycine-rich region characterised by repetitive elements. This includes 2 X 16 AA Gly-rich approximate repeats spanning amino acids 234-433, with repeat 1-1 at positions 234-249 and repeat 1-2 at positions 418-433. Embedded within this region are 2 X 19 AA perfect repeats (amino acids 354-392), specifically repeat 2-1 (amino acids 354-372) and repeat 2-2 (amino acids 374-392). These glycine-rich domains are thought to mediate protein-protein interactions and contribute to the assembly of larger ribonucleoprotein complexes that orchestrate RNA processing events.
Key variants
Pathogenic variants in HNRNPH2 have been documented in individuals with neurodevelopmental disorders. These variants include missense changes that may alter the protein's RNA-binding properties, as well as frameshift and nonsense variants predicted to result in loss of protein function. Given the gene's location on the X chromosome, variant interpretation may consider whether the change affects one or both gene copies and how X-inactivation patterns influence clinical presentation in individuals with two X chromosomes.
No pathogenic or likely-pathogenic ClinVar variants recorded yet for this gene.
Associated conditions
Variants in HNRNPH2 have been associated with a spectrum of neurodevelopmental features. Clinical reports describe individuals with intellectual disability, developmental delay, and seizure disorders linked to changes in this gene. The phenotypic spectrum can be variable, and features may include speech and motor delays, behavioural differences, and epilepsy with onset in infancy or early childhood. The gene's inclusion on NHS panels for early onset or syndromic epilepsy, intellectual disability, and foetal anomalies reflects its recognised role in these clinical contexts within the UK healthcare system.
No disease links recorded for this gene in our reference set.
UK clinical status
HNRNPH2 is included on several NHS Genomic Medicine Service gene panels, indicating its relevance to UK clinical genomic testing pathways. The gene appears on the DDG2P panel with green classification, signifying a definitive evidence level for its association with developmental disorders. It is also listed on the Early onset or syndromic epilepsy panel (green, R59), the Fetal anomalies panel (green, R21), and the Intellectual disability panel (green, R29). These designations mean that HNRNPH2 variants may be reported in diagnostic genomic testing for individuals presenting with relevant clinical features within NHS services.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Frequently asked questions
What does the HNRNPH2 gene do?
HNRNPH2 encodes a protein that binds to RNA molecules in the cell nucleus and helps control how genetic information is processed into functional proteins. This includes regulating which segments of RNA are included in the final messenger RNA, a process particularly important for normal brain development.
Why is HNRNPH2 on the X chromosome significant?
Because HNRNPH2 is located on the X chromosome, inheritance follows X-linked patterns. Individuals with one X chromosome may be more likely to show clinical features if they inherit a pathogenic variant, while those with two X chromosomes may have variable presentations depending on which copy of the gene is active in different cells.
Is HNRNPH2 tested on the NHS?
Yes, HNRNPH2 appears on multiple NHS Genomic Medicine Service panels, including those for intellectual disability, early onset epilepsy, and foetal anomalies. Testing may be offered when an individual's clinical features align with the conditions associated with this gene.