3-196659748-G-A

Position:

• chr3-196659748-G-A

Variant summary

Our verdict is Likely benign. Variant got -3 ACMG points: 2P and 5B. PM2 BP4_Strong BS1_Supporting

The NM_198565.3(NRROS):​c.109-4G>A variant causes a splice region, splice polypyrimidine tract, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000193 in 1,450,166 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.000019 (0 hom.)
• Consequence: NRROS NM_198565.3 splice_region, splice_polypyrimidine_tract, intron
• Scores: Splicing: ADA: 0.00003432
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.365

Genes affected

NRROS (HGNC:24613): (negative regulator of reactive oxygen species) Enables transforming growth factor beta binding activity. Predicted to be involved in several processes, including microglia development; sequestering of TGFbeta in extracellular matrix; and transforming growth factor beta1 activation. Located in cell surface. [provided by Alliance of Genome Resources, Apr 2022]

PIGX (HGNC:26046): (phosphatidylinositol glycan anchor biosynthesis class X) This gene encodes a type I transmembrane protein in the endoplasmic reticulum (ER). The protein is an essential component of glycosylphosphatidylinositol-mannosyltransferase I, which transfers the first of the four mannoses in the GPI-anchor precursors during GPI-anchor biosynthesis. Studies in rat indicate that the protein is translated from a non-AUG translation initiation site. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Oct 2009]

ACMG classification

Verdict is Likely_benign. Variant got -3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.83).
• BS1: Variant frequency is greater than expected in population eas. gnomad4_exome allele frequency = 0.0000193 (28/1450166) while in subpopulation EAS AF= 0.0000253 (1/39458). AF 95% confidence interval is 0.0000164. There are 0 homozygotes in gnomad4_exome. There are 20 alleles in male gnomad4_exome subpopulation. Median coverage is 30. This position pass quality control queck. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
NRROS	NM_198565.3	c.109-4G>A		splice_region_variant, splice_polypyrimidine_tract_variant, intron_variant		ENST00000328557.5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
NRROS	ENST00000328557.5	c.109-4G>A		splice_region_variant, splice_polypyrimidine_tract_variant, intron_variant		1	NM_198565.3	P1
PIGX	ENST00000426755.5	c.-12+5101G>A		intron_variant		3

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 0.0000193 AC: 28 AN: 1450166 Hom.: 0 Cov.: 30 AF XY: 0.0000278 AC XY: 20 AN XY: 720112

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000253

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000235

Gnomad4 OTH exome AF: 0.0000167

GnomAD4 genome Cov.: 31

Alfa AF: 0.0000313 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Seizures, early-onset, with neurodegeneration and brain calcifications Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Laboratorio de Genetica e Diagnostico Molecular, Hospital Israelita Albert Einstein

Jan 05, 2023

ACMG classification criteria: PM2 moderated -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.83
CADD	Benign	7.4
DANN	Benign	0.82

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.000034
dbscSNV1_RF	Benign	0.0020
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

LitVar

Other links and lift over

dbSNP: rs199961460; hg19: chr3-196386619;