Mendeliome
Gene: PNPT1 Green List (high evidence)Green List (high evidence)
6 additional unrelated cases identified by Pennisi et al., 2022 (PMID: 33199448) with biallelic variants in this gene.Created: 1 Apr 2022, 9:25 p.m. | Last Modified: 1 Apr 2022, 9:25 p.m.
Panel Version: 0.12453
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Phenotypes
Combined oxidative phosphorylation deficiency 13, OMIM:614932
Publications
Green List (high evidence)
Additional reports for association between mono allelic variants and SCA:
PMID:39729134 (2024) reported an 11-year-old male of Indian descent with childhood-onset ataxia and severe sensorineural hearing loss. Genetic analysis identified heterozygous 3' splice site variant in the PNPT1 gene (c.2014-3 C > G).
PMID:39899068 (2025) reported a 1-year-8-month-old female proband of Brazilian descent with Spinocerebellar Ataxia 25 that presented with progressive ataxia, cerebellar atrophy, and sensory neuropathy. She was identified with a novel heterozygous truncating variant in PNPT1 (c.2068del), which she inherited from her father. Although the father was previously reported as asymptomatic, he was affected with axonal and demyelinating polyneuropathy but not ataxia upon detailed examination.
PMID:39924761 (2025) reported two unrelated families, where all individuals presented with sensory ataxic neuropathy (SAN), while some individuals developed cerebellar signs. Analysis of WGS variant data through the 100,000 Genomes Project identified two different heterozygous variants in these families. Family 1 underwent a 'quad' study and the previously reported c.2014‐3C>G variant segregated in all affected family members and was absent in all unaffected family members. Sanger sequencing confirmed segregation in two other individuals. c.2014‐3C>G is the same variant that was found in the 3-generation Australian family reported by PMID:35411967, where unaffected family members harboured the variant. A novel nonsense variant (c.2143C>T/ p.Arg715Ter) was found in both affected members of Family 2.
PMID:40757543 (2024) reported an 18-year-old male presented with slowly progressive infancy-onset spasticity of the lower limbs and cerebellar ataxia, associated with painless strabismus, intellectual disability, urinary incontinence, bilateral progressive visual loss, and cognitive decline since early adolescence. The patient was identified with a heterozygous pathogenic variant c.162-1G>A in PNPT1 gene.Created: 28 Oct 2025, 7:39 a.m. | Last Modified: 28 Oct 2025, 7:39 a.m.
Panel Version: 1.3476
Three families reported with heterozygous variants and SCA25. Incomplete penetrance in one of the families. In the third family, the variant was inherited from an asymptomatic 80+ year old. Note bi-allelic variants in this gene cause a mitochondrial disorder. Exact mechanism through which mono-allelic variants cause SCA25 not elucidated: authors speculate abnormal accumulation of mitochondrial RNA with subsequent leakage into the cytosol that may trigger a type 1 interferon response leading to neuroinflammation with neuronal dysfunction or neuronal loss.Created: 14 Jul 2022, 9:56 a.m. | Last Modified: 14 Jul 2022, 9:56 a.m.
Panel Version: 1.114
Comment when marking as ready: Those initially presenting with deafness may be at risk of progressive complex neurological course.Created: 22 Feb 2020, 7:41 a.m. | Last Modified: 22 Feb 2020, 7:41 a.m.
Panel Version: 0.1418
Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Phenotypes
Spinocerebellar ataxia 25, MIM# 608703
Publications
Green List (high evidence)
Biallelic variants reported in patients with a wide clinical heterogeneity ranging from non-syndromic hearing loss to multisystemic Leigh syndrome.
Possible genotype-phenotype correlation: Combination of missense and a null allele resulting in less residual activity present with white matter abnormalities. Patients with only missense variants did not have white matter abnormalities (PMID: 28594066)Created: 21 Feb 2020, 8:56 a.m. | Last Modified: 21 Feb 2020, 8:56 a.m.
Panel Version: 0.1415
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Phenotypes
Combined oxidative phosphorylation deficiency 13 (MIM#614932); Deafness, autosomal recessive 70 (MIM#614934)
Publications
Publications for gene: PNPT1 were set to 31752325; 30244537; 28594066; 28645153; 33199448; 33199448
Phenotypes for gene: PNPT1 were changed from Combined oxidative phosphorylation deficiency 13 (MIM#614932); Deafness, autosomal recessive 70 (MIM#614934) to Combined oxidative phosphorylation deficiency 13 (MIM#614932); Deafness, autosomal recessive 70 (MIM#614934); Spinocerebellar ataxia 25, MIM# 608703
Publications for gene: PNPT1 were set to 31752325; 30244537; 28594066; 28645153; 33199448
Mode of inheritance for gene: PNPT1 was changed from BIALLELIC, autosomal or pseudoautosomal to BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Publications for gene: PNPT1 were set to 31752325; 30244537; 28594066; 28645153
Gene: pnpt1 has been classified as Green List (High Evidence).
Gene: pnpt1 has been classified as Green List (High Evidence).
Phenotypes for gene: PNPT1 were changed from to Combined oxidative phosphorylation deficiency 13 (MIM#614932); Deafness, autosomal recessive 70 (MIM#614934)
Publications for gene: PNPT1 were set to
Mode of inheritance for gene: PNPT1 was changed from Unknown to BIALLELIC, autosomal or pseudoautosomal
gene: PNPT1 was added gene: PNPT1 was added to Mendeliome_VCGS. Sources: Expert Review Green,Victorian Clinical Genetics Services Mode of inheritance for gene: PNPT1 was set to Unknown
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.