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LHX3
LIM homeobox 3
LHX3 is located on the long (q) arm of chromosome 9, at band 9q34.3. Arm ratio per GRCh38 - banding schematic.
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Overview
LHX3 (LIM homeobox 3) is located on chromosome 9 at position 9q34.3 and encodes a transcription factor belonging to the LIM-homeodomain family. Transcription factors are proteins that bind to specific DNA sequences and regulate whether particular genes are switched on or off during development. The LHX3 protein is essential during embryonic development for establishing the proper formation of the anterior pituitary gland, which secretes multiple hormones controlling vital bodily functions. Additionally, LHX3 contributes to the development of specific motor neurones in the spinal cord. Pathogenic variants in this gene can impair these developmental processes, resulting in congenital hormone deficiencies and associated physical features.
What the gene does
The LHX3 protein functions as a transcription factor that orchestrates gene expression programmes required for pituitary organogenesis. During embryonic development, LHX3 works alongside other regulatory proteins to specify the identity of pituitary cell types that will later produce growth hormone, thyroid-stimulating hormone, prolactin, and gonadotrophins. The protein achieves this by binding to regulatory regions of DNA near target genes, thereby activating or repressing their transcription. In the developing spinal cord, LHX3 participates in defining the identity and positioning of motor neurones that will later control voluntary muscle movement. The protein's ability to recognise specific DNA sequences depends on its homeobox domain, whilst the LIM domains mediate interactions with other regulatory proteins, allowing LHX3 to integrate multiple developmental signals and coordinate complex gene expression patterns in a tissue-specific manner.
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Chromosome location
LHX3 is positioned on the long arm of chromosome 9 at cytogenetic band 9q34.3, near the telomeric end of the chromosome. The gene spans a relatively compact genomic region and encodes a protein of 397 amino acids. This chromosomal location is part of a region that contains several other genes involved in developmental processes.
Protein structure
The LHX3 protein is organised into distinct functional modules across its 397 amino acids. The N-terminal region contains two tandem LIM zinc-binding domains: LIM zinc-binding 1 spans amino acids 31 to 81, and LIM zinc-binding 2 extends from amino acids 90 to 144. These zinc-finger motifs facilitate protein-protein interactions with transcriptional co-factors. The central portion of the protein features a Homeobox domain (amino acids 157 to 216) responsible for sequence-specific DNA binding, enabling LHX3 to recognise and attach to regulatory elements in the genome. The C-terminal region (amino acids 212 to 397) is disordered, lacking a stable three-dimensional structure, and likely provides flexibility for regulatory interactions and post-translational modifications that fine-tune the protein's activity during development.
Key variants
Pathogenic variants in LHX3 typically result in loss of the protein's normal function, either by disrupting DNA binding, preventing protein-protein interactions, or causing premature termination of the protein sequence. Most disease-causing changes are inherited in an autosomal recessive manner, meaning that affected individuals carry variants on both copies of the gene. The variant spectrum includes missense changes that alter critical amino acids within the functional domains, as well as deletions or nonsense variants that truncate the protein.
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.152G>A | p.Trp51Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Non-acquired combined pituitary hormone deficiency with spine abnormalities |
c.214C>T | p.Arg72Ter | Pathogenic | ★★☆☆ | Non-acquired combined pituitary hormone deficiency with spine abnormalities |
c.562G>T | p.Glu188Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Non-acquired combined pituitary hormone deficiency with spine abnormalities |
c.572C>A | p.Ser191Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Non-acquired combined pituitary hormone deficiency with spine abnormalities |
c.93C>A | p.Cys31Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Non-acquired combined pituitary hormone deficiency with spine abnormalities |
g.(?_139094782)_(139096868_?)del | - | Pathogenic | ★☆☆☆ | not provided |
c.165T>A | p.Cys55Ter | Pathogenic | ★☆☆☆ | not provided |
c.233del | p.Cys78fs | Pathogenic | ★☆☆☆ | not provided |
c.451C>T | p.Arg151Ter | Pathogenic | ★☆☆☆ | Non-acquired combined pituitary hormone deficiency with spine abnormalities |
c.528C>G | p.Tyr176Ter | Pathogenic | ★☆☆☆ | Combined pituitary hormone deficiencies, genetic form |
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
Variants in LHX3 are associated with combined pituitary hormone deficiency, a condition characterised by inadequate production of multiple pituitary hormones from birth. Affected individuals typically present with deficiencies in growth hormone, thyroid-stimulating hormone, and gonadotrophins, leading to short stature, hypothyroidism, and delayed or absent puberty. Some individuals also exhibit a rigid cervical spine with limited neck rotation, reflecting LHX3's developmental role beyond the pituitary. The severity and specific combination of hormone deficiencies can vary depending on the nature and location of the pathogenic variant within the gene.
No disease links recorded for this gene in our reference set.
UK clinical status
Within the NHS Genomic Medicine Service, LHX3 appears on multiple clinical gene panels with green (high evidence) classification. It is included in the Pituitary hormone deficiency panel (R159), the Congenital hypothyroidism panel (R145), and the Fetal anomalies panel (R21), reflecting its role in endocrine development and prenatal diagnosis. LHX3 also features in panels for IUGR and IGF abnormalities and Monogenic hearing loss (R67), as well as the Developmental Disorders Genotype-to-Phenotype (DDG2P) resource. This multi-panel presence indicates that testing for LHX3 variants may be appropriate in various clinical scenarios involving pituitary dysfunction or complex developmental phenotypes identified during pregnancy or early childhood.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Frequently asked questions
What does the LHX3 gene do?
LHX3 encodes a transcription factor that controls gene activity during the development of the pituitary gland and certain spinal motor neurones. It ensures that hormone-producing cells form correctly in the embryo.
How are LHX3 variants inherited?
Most pathogenic LHX3 variants are inherited in an autosomal recessive pattern, meaning an individual must inherit a variant from both parents to be affected. Carriers with one variant copy typically do not show symptoms.
What testing is available for LHX3 in the NHS?
LHX3 is included in several NHS gene panels for pituitary hormone deficiency, congenital hypothyroidism, and foetal anomalies. Testing may be offered when a patient presents with multiple pituitary hormone deficiencies or relevant developmental features identified during clinical assessment.