Intellectual disability syndromic and non-syndromic
Gene: TMEM63B Green List (high evidence)Green List (high evidence)
PMID: 42259295 Chan et al 2026 report five individuals from four unrelated families with childhood interstitial lung disease and biallelic predicted loss-of-function variants in TMEM63B. Other phenotypic characteristics include moderate/severe developmental delay (5/5), white matter changes, (1/5), mild global atrophy on brain imaging (1/5) and severe short stature (2/5). None of the individuals had epilepsy or hearing loss. Individuals were from Saudi Arabian, Malay, European and Native American ethnicities. 5 different variants were reported including nonsense, frameshift and splice donor variants. The authors report that while there are 53 TMEM63B pLoF variants in gnomAD v.4.1.0 database none are in the homozygous state. Histopathological examination of lung tissue also showed a pattern consistent with surfactant dysfunction. The authors conclude that biallelic loss of function variants result in a distinct pulmonary-predominant phenotype characterized by hypoxaemia, early-onset respiratory failure, histological features of surfactant dysfunction, and chest imaging consistent with chILD.Created: 30 Jun 2026, 7:34 a.m. | Last Modified: 30 Jun 2026, 7:34 a.m.
Panel Version: 2.19
17 unrelated individuals with severe early-onset developmental and epileptic encephalopathy (DEE), intellectual disability, and severe motor and cortical visual impairment were identified with ten distinct heterozygous variants inTMEM63B. The variants occurred de novo in 16/17 individuals for whom parental DNA was available and either missense or in-frame. All individuals had global developmental delay, with moderate-to-profound intellectual disability and severe motor impairment. All individuals had early-onset drug-resistant epilepsy, whose onset ranged from birth to 3 years but occurred within the first year in 14/17 (82%) and in the first month of life in 6/17 (35%).
Sources: LiteratureCreated: 31 Jul 2023, 8:11 p.m.
Mode of inheritance
BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Phenotypes
Developmental and epileptic encephalopathy 118, MIM# 621250; Lung-brain developmental disorder, MIM# 621645
Publications
Phenotypes for gene: TMEM63B were changed from Developmental and epileptic encephalopathy 118, MIM# 621250; Hereditary pulmonary alveolar proteinosis, MONDO:0012580, TMEM63B-related to Developmental and epileptic encephalopathy 118, MIM# 621250; Lung-brain developmental disorder, MIM# 621645
Phenotypes for gene: TMEM63B were changed from Developmental and epileptic encephalopathy 118, MIM# 621250 to Developmental and epileptic encephalopathy 118, MIM# 621250; Hereditary pulmonary alveolar proteinosis, MONDO:0012580, TMEM63B-related
Publications for gene: TMEM63B were set to 37421948
Mode of inheritance for gene: TMEM63B was changed from MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted to BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Phenotypes for gene: TMEM63B were changed from developmental and epileptic encephalopathy, MONDO:0100062, TMEM63B-related to Developmental and epileptic encephalopathy 118, MIM# 621250
Gene: tmem63b has been classified as Green List (High Evidence).
Gene: tmem63b has been classified as Green List (High Evidence).
gene: TMEM63B was added gene: TMEM63B was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: TMEM63B was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: TMEM63B were set to 37421948 Phenotypes for gene: TMEM63B were set to developmental and epileptic encephalopathy, MONDO:0100062, TMEM63B-related Review for gene: TMEM63B was set to GREEN
If promoting or demoting a gene, please provide comments to justify a decision to move it.
Genes included in a Genomics England gene panel for a rare disease category (green list) should fit the criteria A-E outlined below.
These guidelines were developed as a combination of the ClinGen DEFINITIVE evidence for a causal role of the gene in the disease(a), and the Developmental Disorder Genotype-Phenotype (DDG2P) CONFIRMED DD Gene evidence level(b) (please see the original references provided below for full details). These help provide a guideline for expert reviewers when assessing whether a gene should be on the green or the red list of a panel.
A. There are plausible disease-causing mutations(i) within, affecting or encompassing an interpretable functional region(ii) of this gene identified in multiple (>3) unrelated cases/families with the phenotype(iii).
OR
B. There are plausible disease-causing mutations(i) within, affecting or encompassing cis-regulatory elements convincingly affecting the expression of a single gene identified in multiple (>3) unrelated cases/families with the phenotype(iii).
OR
C. As definitions A or B but in 2 or 3 unrelated cases/families with the phenotype, with the addition of convincing bioinformatic or functional evidence of causation e.g. known inborn error of metabolism with mutation in orthologous gene which is known to have the relevant deficient enzymatic activity in other species; existence of an animal model which recapitulates the human phenotype.
AND
D. Evidence indicates that disease-causing mutations follow a Mendelian pattern of causation appropriate for reporting in a diagnostic setting(iv).
AND
E. No convincing evidence exists or has emerged that contradicts the role of the gene in the specified phenotype.
(i)Plausible disease-causing mutations: Recurrent de novo mutations convincingly affecting gene function. Rare, fully-penetrant mutations - relevant genotype never, or very rarely, seen in controls. (ii) Interpretable functional region: ORF in protein coding genes miRNA stem or loop. (iii) Phenotype: the rare disease category, as described in the eligibility statement. (iv) Intermediate penetrance genes should not be included.
It’s assumed that loss-of-function variants in this gene can cause the disease/phenotype unless an exception to this rule is known. We would like to collect information regarding exceptions. An example exception is the PCSK9 gene, where loss-of-function variants are not relevant for a hypercholesterolemia phenotype as they are associated with increased LDL-cholesterol uptake via LDLR (PMID: 25911073).
If a curated set of known-pathogenic variants is available for this gene-phenotype, please contact us at panelapp@genomicsengland.co.uk
We classify loss-of-function variants as those with the following Sequence Ontology (SO) terms:
Term descriptions can be found on the PanelApp homepage and Ensembl.
If you are submitting this evaluation on behalf of a clinical laboratory please indicate whether you report variants in this gene as part of your current diagnostic practice by checking the box
Standardised terms were used to represent the gene-disease mode of inheritance, and were mapped to commonly used terms from the different sources. Below each of the terms is described, along with the equivalent commonly-used terms.
A variant on one allele of this gene can cause the disease, and imprinting has not been implicated.
A variant on the paternally-inherited allele of this gene can cause the disease, if the alternate allele is imprinted (function muted).
A variant on the maternally-inherited allele of this gene can cause the disease, if the alternate allele is imprinted (function muted).
A variant on one allele of this gene can cause the disease. This is the default used for autosomal dominant mode of inheritance where no knowledge of the imprinting status of the gene required to cause the disease is known. Mapped to the following commonly used terms from different sources: autosomal dominant, dominant, AD, DOMINANT.
A variant on both alleles of this gene is required to cause the disease. Mapped to the following commonly used terms from different sources: autosomal recessive, recessive, AR, RECESSIVE.
The disease can be caused by a variant on one or both alleles of this gene. Mapped to the following commonly used terms from different sources: autosomal recessive or autosomal dominant, recessive or dominant, AR/AD, AD/AR, DOMINANT/RECESSIVE, RECESSIVE/DOMINANT.
A variant on one allele of this gene can cause the disease, however a variant on both alleles of this gene can result in a more severe form of the disease/phenotype.
A variant in this gene can cause the disease in males as they have one X-chromosome allele, whereas a variant on both X-chromosome alleles is required to cause the disease in females. Mapped to the following commonly used term from different sources: X-linked recessive.
A variant in this gene can cause the disease in males as they have one X-chromosome allele. A variant on one allele of this gene may also cause the disease in females, though the disease/phenotype may be less severe and may have a later-onset than is seen in males. X-linked inactivation and mosaicism in different tissues complicate whether a female presents with the disease, and can change over their lifetime. This term is the default setting used for X-linked genes, where it is not known definitately whether females require a variant on each allele of this gene in order to be affected. Mapped to the following commonly used terms from different sources: X-linked dominant, x-linked, X-LINKED, X-linked.
The gene is in the mitochondrial genome and variants within this can cause this disease, maternally inherited. Mapped to the following commonly used term from different sources: Mitochondrial.
Mapped to the following commonly used terms from different sources: Unknown, NA, information not provided.
For example, if the mode of inheritance is digenic, please indicate this in the comments and which other gene is involved.