Mendeliome
Gene: TIMMDC1 Green List (high evidence)Green List (high evidence)
PMID:36349561 report the same homozygous missense variant p.(Arg137His) was identified in 4 fetuses from 2 families terminated for corpus callosum defects. Autopsies showed global hypotrophy and similar facial dysmorphism with coarse face, microcephaly, and microlissencephaly or gyration delay. All 4 fetuses were diagnosed with complete agenesis of CC. Immunoblot analyses of muscle homogenates revealed a strong reduction in the abundance of the TIMMDC1 protein. There was decreased abundance of complex I subunits in muscle tissue.
PMID:33278652 reported two siblings from a Dutch family presenting in infancy with hypotonia and respiratory insufficiency and a rapidly progressive and fatal disease course. A muscle biopsy demonstrated complex I deficiency in brother 2. Each was compound het for the NMD-predicted variant p.(Arg129*) and the previously reported recurrent deep intronic variant c.596+2146A>G.
In total, 3 variants in 6 families with mitochondrial complex I deficiency have been reported. A deep intronic variant shown to affect splicing is recurrent.Created: 1 Dec 2022, 4:43 a.m. | Last Modified: 1 Dec 2022, 4:43 a.m.
Panel Version: 1.526
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Phenotypes
Mitochondrial complex I deficiency, nuclear type 31 MIM#618251
Publications
Variants in this GENE are reported as part of current diagnostic practice
I don't know
A deep intronic variant (c.597-1340A>G, only detectable by WGS) that causes a splicing aberration was identified in a homozygous state in 3 unrelated cases from different ethnic backgrounds. A patient with Leigh-like syndrome had a homozygous stopgain variant in PDHX and a homozygous stopgain variant in TIMMDC1 (p.Arg225*). The TIMMDC1 mutant protein could still rescue complex I assembly in TIMMDC1 knockout cells and the patient’s clinical phenotype was not clearly distinct from that of other patients with the same PDHX defect.
Sources: NHS GMSCreated: 20 Mar 2020, 4:41 a.m.
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Phenotypes
Mitochondrial complex I deficiency, nuclear type 31 MIM#618251
Publications
Gene: timmdc1 has been classified as Green List (High Evidence).
Gene: timmdc1 has been classified as Amber List (Moderate Evidence).
Tag deep intronic tag was added to gene: TIMMDC1.
Gene: timmdc1 has been classified as Amber List (Moderate Evidence).
gene: TIMMDC1 was added gene: TIMMDC1 was added to Mendeliome. Sources: NHS GMS Mode of inheritance for gene: TIMMDC1 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: TIMMDC1 were set to 28604674; 30981218 Phenotypes for gene: TIMMDC1 were set to Mitochondrial complex I deficiency, nuclear type 31 MIM#618251 Review for gene: TIMMDC1 was set to AMBER
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.