Intellectual disability - microarray and sequencing
Gene: NDUFA2 Green List (high evidence)The rating of this gene has been updated following NHS Genomic Medicine Service approval.Created: 9 Mar 2022, 3:40 p.m. | Last Modified: 9 Mar 2022, 3:40 p.m.
Panel Version: 3.1510
Green List (high evidence)
Comment on list classification: There is enough evidence for this gene to be rated GREEN at the next major review - at least four unrelated cases reported with DD/ID, mostly following a period of regression.Created: 3 Aug 2020, 12:57 p.m. | Last Modified: 3 Aug 2020, 12:57 p.m.
Panel Version: 3.221
Associated with Mitochondrial complex I deficiency, nuclear type 13 in OMIM, but not in G2P.
PMID: 18513682 (2008) - A homozygous variant (c.208+5 G>A) which induced alternative splicing and thereby resulting in a truncated protein, was detected in a patient with hypertrophic cardiomyopathy, cerebral atrophy and hypoplasia of the corpus callosum. Developmental delay was apparent from birth. Following a varicella infection, the patient developed severe acidosis, seizures, and coma, and died of cardiovascular arrest at age 11 months. Functional studies of patient fibroblasts showed disrupted mitochondrial membrane potential and assembly, stability, and activity of complex I. Furthermore, these defects could be restored by transduction with a baculoviral vector containing the wild-type NDUFA2 gene.
PMID: 28857146 (2018) - Two unrelated cases. In a 12-year-old female with cystic leukodystrophy, WES revealed a homozygous variant in NDUFA2 (c.134A>C, p.Lys45Thr). She exhibited developmental regression until age 12 months, followed by stabilisation. Nonetheless, moderate ID was noted.
In the second leukoencephalopathy patient, compound heterozygous variants were identified in NDUFA2 ([c.134A>C, p.Lys45Thr];[c.225del, p.Asn76Metfs*4]). The patient presented at 8 months with fever, failure to thrive and developmental regression. At 4-years-old she was microcephalic, could speak in short sentences and walked with a walker, but used a wheelchair for long distances.
PMID: 32154054 (2020) - Homozygous missense variant (c.170A>C, p.Glu57Ala) identified in a 4-year-old female presenting with cavitating and tigroid‐like leukoencephalopathy. She said her first words at 10 months of age and by the age of 18 months she was able to say 10 words. By 20 months, she experienced a slow regression of both motor and verbal skills without any apparent trigger, but subsequently regained limited motor and language skills over the following months.Created: 3 Aug 2020, 12:51 p.m. | Last Modified: 3 Aug 2020, 12:51 p.m.
Panel Version: 3.220
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Phenotypes
Mitochondrial complex I deficiency, nuclear type 13, 618235
Publications
Green List (high evidence)
Three unrelated families reported, DD/IDD in all.
Sources: Expert listCreated: 4 Mar 2020, 6:44 a.m.
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Phenotypes
Mitochondrial complex I deficiency, nuclear type 13, MIM#618235
Publications
Variants in this GENE are reported as part of current diagnostic practice
Tag for-review was removed from gene: NDUFA2.
Source Expert Review Green was added to NDUFA2. Rating Changed from Amber List (moderate evidence) to Green List (high evidence)
Gene: ndufa2 has been classified as Amber List (Moderate Evidence).
Tag watchlist was removed from gene: NDUFA2. Tag for-review tag was added to gene: NDUFA2.
Tag watchlist tag was added to gene: NDUFA2.
gene: NDUFA2 was added gene: NDUFA2 was added to Intellectual disability. Sources: Expert list Mode of inheritance for gene: NDUFA2 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: NDUFA2 were set to 18513682; 28857146 Phenotypes for gene: NDUFA2 were set to Mitochondrial complex I deficiency, nuclear type 13, MIM#618235 Review for gene: NDUFA2 was set to GREEN gene: NDUFA2 was marked as current diagnostic
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 [email protected]
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.