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Intellectual disability

Gene: RNF220

Amber List (moderate evidence)
RNF220 (ring finger protein 220)
EnsemblGeneIds (GRCh38): ENSG00000187147
EnsemblGeneIds (GRCh37): ENSG00000187147
OMIM: 616136, Gene2Phenotype
RNF220 is in 5 panels

2 reviews

Ivone Leong (Genomics England Curator)

Comment on list classification: New gene added by Konstantinos Varvagiannis. This gene is currently not associated with a phenotype in OMIM or Gene2Phenotype. There are >3 cases for this gene; however, 3 of the cases described in PMID:33964137 are of Roma descent and haplotype analysis has shown that the variant found in these families are due to a founder effect (c.1094G>A, p.Arg365Gly). A separate Roma family also has the same variant (c.1094G>A, p.Arg365Gly). An Italian family with similar phenotypes has a different variant (c.1088G>A, p.Arg363Gly). The authors also report on in vitro and in vivo studies.

There is enough evidence to support a gene-disease association; however, the ID severity in these patients do not meet the criteria (moderate to severe) for this panel (patients show mild (mostly) to moderate severity). Therefore, this gene has been given an Amber rating.
Created: 6 Oct 2021, 3:06 p.m. | Last Modified: 6 Oct 2021, 3:06 p.m.
Panel Version: 3.1328
Created: 6 Oct 2021, 3:06 p.m.
Last Modified: 6 Oct 2021, 3:06 p.m.
Panel version: 3.1328

Konstantinos Varvagiannis (Other)

Green List (high evidence)

Sferra et al (2021 - PMID: 33964137) provide extensive evidence that biallelic RNF220 mutations cause a disorder characterized by hypomyelinating leukodystrophy, ataxia (9/9 - onset 1-5y), borderline intellectual functioning (3/9) / intellectual disability (5/9 - in most cases mild), sensorineural deafness (9/9) with complete hearing loss in the first decade of life, hepatopathy (9/9) with associated periportal fibrosis, and dilated cardiomyopathy (9/9) which was fatal.

Other neurologic manifestations apart from ataxia incl. hyperreflexia (8/8), spastic paraplegia (9/9), dysarthria (9/9), peripheral neuropathy (4/9), seizures in one case (1/9). Upon brain MRI there was thin corpus callosum (9/9) or cerebellar atrophy in some (2/9).

The authors identified homozygosity for 2 recurrent missense RNF220 variants in affected members belonging to these 5 broad consanguineous pedigrees (7 families), namely NM_018150.4:c.1094G>A / p.Arg365Gly in 4 Roma families in the context of a shared haplotype (/founder effect) as well as c.1088G>A / p.Arg363Gly in a large pedigree from southern Italy initially reported by Leuzzi et al (2000 - PMID: 10881263).

Extensive segregation analyses were carried out including several affected and unaffected members.

RNF220 encodes ring finger protein 220, which functions as an E3 ubiquitin ligase. Previous studies have shown among others a role in modulation of Sonic hedgehog/GLI signaling and cerebellar development

Evidence for the role of RNF220 included relevant expression, localization within the cell, interaction partners (lamin B1, 20S proteasome), similarities with other laminopathies in terms of phenotype, etc :
*RNF220 has a relevant expression pattern in CNS (based on qRT-PCR analyses in human brain, cerebellum, cerebral cortex / mRNA levels in human fetal CNS with higher expression in cerebellum, spinal cord and cortex / previous GTEx data / protein levels in mouse CNS)
*The protein displays nuclear localization based on iPSC cells differentiated to motor neurons (also supported by data from the Human Protein Atlas). Transfection of COS-1 cells demonstrated localization primarily to the nucleus (as also previously demonstrated in HEK293T cells) in vesicle like structures with ASF2/SF2 colocalization suggesting enrichment in nuclear speckles. There was also partial co-distribution with the 20S proteasome. R363Q and R365Q additionally coalesced in the cytoplasm forming protein aggregates/inclusions.
*Immunofluorescence studies in patient fibroblasts also confirmed abnormal increase of the protein in the cytoplasm and increased fluorescence with the 20S proteasome.
*Proteomic identification of RNF220-interacting proteins in transfected HEK293T cells demonstrated enrichment for all members of the lamin protein family (incl . lamin B1, AC, B2).
*RNAi-mediated downregulation of RNF222 in Drosophila suggested altered subcellular localization and accumulation of the fly orthologue for human lamin B1.
*Immunoprecipitation of lamin B1 from the nuclear matrix of cerebellar cells suggested significant interaction of endogenous lamin B1 with RNF220, while transfection studies in HEK293T cells for wt/mt suggested reduced binding to endogenous lamin B1 for RNF220 mt compared to wt (more prominent for R365Q). RNF220 mutants also reduced ubiquitination of nuclear lamin B1 compared to wt.
*Patient fibroblasts immunostained with different nuclear envelope markers displayed abnormal nuclear shapes with multiple invaginations and lobulations, findings also observed in laminopathies.

There is currently no associated phenotype in OMIM or G2P. SysID includes RNF220 among the current primary ID genes.

Consider inclusion in panels for leukodystrophies, childhood onset ataxia, sensorineural hearing loss, corpus callosum anomalies, cardiomyopathies, hepatopathies, etc in all cases with green rating.
Sources: Literature, Other
Created: 16 Aug 2021, 12:24 p.m.

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
Leukodystrophy; CNS hypomyelination; Ataxia; Intellectual disability; Sensorineural hearing impairment; Elevated hepatic transaminases; Hepatic fibrosis; Dilated cardiomyopathy; Spastic paraplegia; Dysarthria; Abnormality of the corpus callosum

Publications

Created: 16 Aug 2021, 12:24 p.m.

Panel version: 3.1222

Details

Mode of Inheritance
BIALLELIC, autosomal or pseudoautosomal
Sources
  • Expert Review Amber
Phenotypes
  • Intellectual disability, MONDO:0001071
OMIM
616136
Clinvar variants
Variants in RNF220
Penetrance
Complete
Publications
Panels with this gene

History Filter Activity

6 Oct 2021, Gel status: 2

Set Phenotypes

Ivone Leong (Genomics England Curator)

Phenotypes for gene: RNF220 were changed from Leukodystrophy; CNS hypomyelination; Ataxia; Intellectual disability; Sensorineural hearing impairment; Elevated hepatic transaminases; Hepatic fibrosis; Dilated cardiomyopathy; Spastic paraplegia; Dysarthria; Abnormality of the corpus callosum to Intellectual disability, MONDO:0001071

6 Oct 2021, Gel status: 2

Entity classified by Genomics England curator

Ivone Leong (Genomics England Curator)

Gene: rnf220 has been classified as Amber List (Moderate Evidence).

16 Aug 2021, Gel status: 0

Created, Added New Source, Set mode of inheritance, Set publications, Set Phenotypes, Set penetrance

Konstantinos Varvagiannis (Other)

gene: RNF220 was added gene: RNF220 was added to Intellectual disability. Sources: Literature,Other Mode of inheritance for gene: RNF220 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: RNF220 were set to 33964137; 10881263 Phenotypes for gene: RNF220 were set to Leukodystrophy; CNS hypomyelination; Ataxia; Intellectual disability; Sensorineural hearing impairment; Elevated hepatic transaminases; Hepatic fibrosis; Dilated cardiomyopathy; Spastic paraplegia; Dysarthria; Abnormality of the corpus callosum Penetrance for gene: RNF220 were set to Complete Review for gene: RNF220 was set to GREEN