3-139355756-AG-A

Position:

• chr3-139355756-AG-A

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PVS1_Strong PM2

The NM_020191.4(MRPS22):​c.955delG​(p.Asp319fs) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,814 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: MRPS22 NM_020191.4 frameshift
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.821

Genes affected

MRPS22 (HGNC:14508): (mitochondrial ribosomal protein S22) Mammalian mitochondrial ribosomal proteins are encoded by nuclear genes and help in protein synthesis within the mitochondrion. Mitochondrial ribosomes (mitoribosomes) consist of a small 28S subunit and a large 39S subunit. They have an estimated 75% protein to rRNA composition compared to prokaryotic ribosomes, where this ratio is reversed. Another difference between mammalian mitoribosomes and prokaryotic ribosomes is that the latter contain a 5S rRNA. Among different species, the proteins comprising the mitoribosome differ greatly in sequence, and sometimes in biochemical properties, which prevents easy recognition by sequence homology. This gene encodes a 28S subunit protein that does not seem to have a counterpart in prokaryotic and fungal-mitochondrial ribosomes. This gene lies telomeric of and is transcribed in the opposite direction from the forkhead box L2 gene. A pseudogene corresponding to this gene is found on chromosome Xq. [provided by RefSeq, Jul 2008]

MRPS22 (HGNC:):

COPB2 (HGNC:2232): (COPI coat complex subunit beta 2) The Golgi coatomer complex (see MIM 601924) constitutes the coat of nonclathrin-coated vesicles and is essential for Golgi budding and vesicular trafficking. It consists of 7 protein subunits, including COPB2.[supplied by OMIM, Jul 2002]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most 50 bp of the penultimate exon, not predicted to undergo nonsense mediated mRNA decay. Fraction of 0.118 CDS is truncated, and there are 0 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MRPS22	NM_020191.4	c.955delG	p.Asp319fs	frameshift_variant	7/8	ENST00000680020.1	NP_064576.1
MRPS22	NM_001363893.1	c.952delG	p.Asp318fs	frameshift_variant	7/8		NP_001350822.1
MRPS22	NM_001363857.1	c.832delG	p.Asp278fs	frameshift_variant	7/8		NP_001350786.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MRPS22	ENST00000680020.1	c.955delG	p.Asp319fs	frameshift_variant	7/8		NM_020191.4	ENSP00000505414.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461814 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 727216

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Inborn genetic diseases Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Feb 01, 2022

The c.955delG (p.D319Ifs*7) alteration, located in exon 7 (coding exon 7) of the MRPS22 gene, consists of a deletion of one nucleotide at position 955, causing a translational frameshift with a predicted alternate stop codon after 7 amino acids. This alteration occurs at the 3' terminus of the MRPS22 gene, is not expected to trigger nonsense-mediated mRNA decay, and only impacts the last 11% of the protein. The exact functional effect of this alteration is unknown. This variant was not reported in population-based cohorts in the Genome Aggregation Database (gnomAD). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr3-139074598;