Mendeliome
Gene: MCOLN1 Green List (high evidence)Green List (high evidence)
There is sufficient evidence for this gene to be added with a green rating in "Cone-rod Dystrophy" panel (3147) as patients with MCOLN1-associated mucolipidosis IV present with ocular phenotypes including retinal dystrophy.
Mucolipidosis type IV caused by biallelic variants in MCOLN1 gene ism a lysosomal disease that primarily affects the central nervous system. It manifests with severely impaired psychomotor development, and later onset, gradual neurological decline paralleled by cerebellar degeneration and neuroaxonal injury. In addition, they also manifest retinal dystrophy, which develops in the first years of life and rapidly progresses in adolescence, leaving patients legally blind by the second decade (PMID:33965501).
The following are some of the reported cases:
PMID:17239335 - Compound heterozygous variants in MCOLN1 were identified in a patient with mucolipidosis type IV (ML IV), who had low visual acuity and cloudy corneas since 2 years of age, progressive decrease in visual acuity since the age of 9 years.
PMID:25156245 - An Italian child with ML IV was identified with homozygous MCOLN1 variants (c.395_397delCTG & c.468_474dupTTGGACC), while his parents were heterozygous for the same variants. Ophthalmological manifestations included esotropia, bilateral corneal clouding and severe myopia.
PMID:35205297 - Six patients from two Omani families with ML IV were identified with a novel variant (c.237+5G>A) in MCOLN1 gene, which is not present in control subjects screened with a high-resolution melting (HRM) assay. The patients displayed ophthalmic manifestations including corneal haziness, pigmentary retinopathy and ERG-rod cone dysfunction.
This gene has also been associated with relevant phenotypes both in OMIM (MIM #252650) and DD and eye panels of Gene2Phenotype (with 'definitive' rating). The ophthalmological manifestations including corneal clouding, progressive retinal degeneration and optic atrophy has been reported as part of the OMIM phenotype.Created: 28 Jul 2023, 6:31 a.m. | Last Modified: 28 Jul 2023, 6:31 a.m.
Panel Version: 1.1045
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Phenotypes
Mucolipidosis IV, OMIM:252650
Publications
Green List (high evidence)
PMID 37972748: 23 affected individuals from 13 families with Lisch epithelial corneal dystrophy. WGS in 2 families and then targeted Sanger sequencing in the other families identified 9 rare heterozygous loss of function variants in MCOLN1. Homozygous and compound-heterozygous state of 4 of 9 LECD-associated variants cause Mucolipidosis IV (MLIV), which comprises neurodegeneration as well as corneal opacity of infantile-onset with epithelial autofluorescent lysosomal inclusions. Six parents of 3 patients with MLIV confirmed to carry pathogenic MCOLN1 variants did not have the LECD phenotype. Heterozygous MCOLN1 variants can be associated with incomplete penetrance and variable expressivity of LECD with an estimated penetrance of 0.2% for MCOLN1 loss-of-function variants based on gnomAD.Created: 4 Apr 2024, 7:39 a.m. | Last Modified: 4 Apr 2024, 7:39 a.m.
Panel Version: 1.1664
Mucolipidosis IV is an autosomal recessive neurodegenerative lysosomal storage disorder characterized by intellectual disability and ophthalmologic abnormalities. There are two common Ashkenazi Jewish founder variants, one of which is a deletion, spanning EX1-EX7.Created: 13 Apr 2021, 9:06 a.m. | Last Modified: 13 Apr 2021, 9:06 a.m.
Panel Version: 0.7142
Mode of inheritance
BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Phenotypes
Mucolipidosis IV, MIM# 252650; MONDO:0009653; Lisch epithelial corneal dystrophy, OMIM# 620763
Publications
Phenotypes for gene: MCOLN1 were changed from Mucolipidosis IV, MIM# 252650; MONDO:0009653 to Mucolipidosis IV, MIM# 252650; MONDO:0009653; Lisch epithelial corneal dystrophy, OMIM# 620763
Publications for gene: MCOLN1 were set to
Mode of inheritance for gene: MCOLN1 was changed from BIALLELIC, autosomal or pseudoautosomal to BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Gene: mcoln1 has been classified as Green List (High Evidence).
Phenotypes for gene: MCOLN1 were changed from to Mucolipidosis IV, MIM# 252650; MONDO:0009653
Mode of inheritance for gene: MCOLN1 was changed from Unknown to BIALLELIC, autosomal or pseudoautosomal
Tag SV/CNV tag was added to gene: MCOLN1.
gene: MCOLN1 was added gene: MCOLN1 was added to Mendeliome_VCGS. Sources: Expert Review Green,Victorian Clinical Genetics Services Mode of inheritance for gene: MCOLN1 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.