rs201779890

Variant names:

• chr1-145927328-C-G
• rs201779890
• NM_005105.5:c.67+32G>C

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 8P and 6B. PP5_Very_Strong BP4 BS1_Supporting BS2

The NM_005105.5(RBM8A):​c.67+32G>C variant causes a intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00482 in 1,603,802 control chromosomes in the GnomAD database, including 52 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic,low penetrance (★★).

• Frequency:
  • Genomes: 𝑓 0.0049 (5 hom., cov: 31)
  • Exomes 𝑓: 0.0048 (47 hom.)
• Consequence: RBM8A NM_005105.5 intron
• Clinical Significance: Pathogenic/Likely pathogenic/Pathogenic, low penetrance criteria provided, multiple submitters, no conflicts P:19 O:1
• Conservation: PhyloP100: 0.828
• Publications: 20 publications found

Genes affected

RBM8A (HGNC:9905): (RNA binding motif protein 8A) This gene encodes a protein with a conserved RNA-binding motif. The protein is found predominantly in the nucleus, although it is also present in the cytoplasm. It is preferentially associated with mRNAs produced by splicing, including both nuclear mRNAs and newly exported cytoplasmic mRNAs. It is thought that the protein remains associated with spliced mRNAs as a tag to indicate where introns had been present, thus coupling pre- and post-mRNA splicing events. Previously, it was thought that two genes encode this protein, RBM8A and RBM8B; it is now thought that the RBM8B locus is a pseudogene. There are two alternate translation start codons with this gene, which result in two forms of the protein. An allele mutation and a low-frequency noncoding single-nucleotide polymorphism (SNP) in this gene cause thrombocytopenia-absent radius (TAR) syndrome. [provided by RefSeq, Jul 2013]

ENSG00000280778 (HGNC:):

LIX1L-AS1 (HGNC:41210): (LIX1L antisense RNA 1)

ACMG classification

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

• PP5: Variant 1-145927328-C-G is Pathogenic according to our data. Variant chr1-145927328-C-G is described in ClinVar as Pathogenic/Likely_pathogenic/Pathogenic,_low_penetrance. ClinVar VariationId is 30465.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.36). . Strength limited to SUPPORTING due to the PP5.
• BS1: Variant frequency is greater than expected in population nfe. GnomAd4 allele frequency = 0.00489 (744/152258) while in subpopulation NFE AF = 0.00723 (492/68018). AF 95% confidence interval is 0.00671. There are 5 homozygotes in GnomAd4. There are 397 alleles in the male GnomAd4 subpopulation. Median coverage is 31. This position passed quality control check. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting
• BS2: High Homozygotes in GnomAd4 at 5 AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
RBM8A	NM_005105.5	c.67+32G>C		intron_variant	Intron 1 of 5	ENST00000583313.7	NP_005096.1
LIX1L-AS1	NR_147182.1	n.381C>G		non_coding_transcript_exon_variant	Exon 2 of 3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
RBM8A	ENST00000583313.7	c.67+32G>C		intron_variant	Intron 1 of 5	1	NM_005105.5	ENSP00000463058.2
ENSG00000280778	ENST00000625258.1	c.-30+39C>G		intron_variant	Intron 1 of 3	5		ENSP00000487094.1

Frequencies

GnomAD3 genomes AF: 0.00489 AC: 744 AN: 152140 Hom.: 5 Cov.: 31

Gnomad AFR AF: 0.000459

Gnomad AMI AF: 0.00658

Gnomad AMR AF: 0.00138

Gnomad ASJ AF: 0.000864

Gnomad EAS AF: 0.000192

Gnomad SAS AF: 0.00104

Gnomad FIN AF: 0.0182

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00723

Gnomad OTH AF: 0.00191

GnomAD2 exomes AF: 0.00547 AC: 1281 AN: 234162 AF XY: 0.00545

Gnomad AFR exome AF: 0.000480

Gnomad AMR exome AF: 0.00136

Gnomad ASJ exome AF: 0.000829

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.0238

Gnomad NFE exome AF: 0.00671

Gnomad OTH exome AF: 0.00462

GnomAD4 exome AF: 0.00482 AC: 6994 AN: 1451544 Hom.: 47 Cov.: 31 AF XY: 0.00475 AC XY: 3422 AN XY: 720966

African (AFR) AF: 0.000600 AC: 20 AN: 33352

American (AMR) AF: 0.00126 AC: 54 AN: 42918

Ashkenazi Jewish (ASJ) AF: 0.00151 AC: 39 AN: 25876

East Asian (EAS) AF: 0.00 AC: 0 AN: 39410

South Asian (SAS) AF: 0.000495 AC: 42 AN: 84892

European-Finnish (FIN) AF: 0.0214 AC: 1131 AN: 52882

Middle Eastern (MID) AF: 0.000522 AC: 3 AN: 5750

European-Non Finnish (NFE) AF: 0.00492 AC: 5447 AN: 1106412

Other (OTH) AF: 0.00430 AC: 258 AN: 60052

GnomAD4 genome AF: 0.00489 AC: 744 AN: 152258 Hom.: 5 Cov.: 31 AF XY: 0.00533 AC XY: 397 AN XY: 74438

African (AFR) AF: 0.000457 AC: 19 AN: 41548

American (AMR) AF: 0.00137 AC: 21 AN: 15286

Ashkenazi Jewish (ASJ) AF: 0.000864 AC: 3 AN: 3472

East Asian (EAS) AF: 0.000193 AC: 1 AN: 5190

South Asian (SAS) AF: 0.00104 AC: 5 AN: 4822

European-Finnish (FIN) AF: 0.0182 AC: 193 AN: 10604

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 294

European-Non Finnish (NFE) AF: 0.00723 AC: 492 AN: 68018

Other (OTH) AF: 0.00189 AC: 4 AN: 2112

Alfa AF: 0.00639 Hom.: 2

Bravo AF: 0.00317

Asia WGS AF: 0.000577 AC: 2 AN: 3478

ClinVar

Significance: Pathogenic/Likely pathogenic/Pathogenic, low penetrance

Submissions summary: Pathogenic:19 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Radial aplasia-thrombocytopenia syndrome Pathogenic:9 Other:1

Jul 10, 2023

Department of Pathology and Laboratory Medicine, Sinai Health System

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: research

- -

Feb 26, 2012

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Jan 06, 2020

Reproductive Health Research and Development, BGI Genomics

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: curation

NG_032654.2(NM_005105.4):c.67+32G>C in the RBM8A gene has an allele frequency of 0.023 in European(non-Finnish) subpopulation in the gnomAD database. Experimental studies have reported that c.67+32G>C leads to a partial decrease in RBM8A expression in vitro, possibly by disrupting a transcription factor binding site (PMID: 22366785). It was detected in multiple individuals with Radial aplasia-thrombocytopenia syndrome, compound heterozygous with a submicroscopic deletion encompassing the RBM8A gene (PMID: 22366785). Taken together, we interprete this variant as Pathogenic/Likely pathogenic variant. ACMG/AMP criteria applied: PS3; PM3_Strong; PP4. -

-

GeneReviews

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

- -

May 04, 2022

Mendelics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jan 24, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic, low penetrance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change falls in intron 1 of the RBM8A gene. It does not directly change the encoded amino acid sequence of the RBM8A protein. Experimental studies have reported that this variant leads to a partial decrease in RBM8A expression in vitro, possibly by disrupting a transcription factor binding site (PMID: 22366785). This variant is present in population databases (rs201779890, gnomAD 2.3%), including at least one homozygous and/or hemizygous individual. This variant has been observed on the opposite chromosome (in trans) from a whole gene deletion of RBM8A in several individuals affected with TAR syndrome (PMID: 22366785). However, it has been reported as homozygous in an unaffected parent (PMID: 22366785). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 30465). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site. In summary, this variant is reported to cause disease. However, as this variant is associated with a lower penetrance than other pathogenic alleles in the RBM8A gene, it has been classified as Pathogenic (low penetrance). -

Aug 14, 2018

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.67+32G>C variant in RBM8A has been reported in >25 individuals with thromb ocytopenia with absent radius (TAR) syndrome, all of whom had a submicroscopic d eletion encompassing the RBM8A gene on the second allele (Albers 2012, Manukjan 2017), suggesting that compound heterozygosity for this variant and a loss of fu nction variant in RBM8A is disease causing. In vitro studies demonstrated that t his variant may lead to reduced gene expression (Albers 2012). Although this var iant has also been identified in 2.5% (562/24044) of Finnish and 0.7% (883/11850 8) of other European chromosomes, including 11 homozygotes, by the Genome Aggreg ation Database (gnomAD, http://exac.broadinstitute.org; dbSNP rs201779890), loss of function variants in RBM8A are very rare in large population studies, sugges ting that compound heterozygosity for the c.67+32G>C variant and a loss of funct ion variant in RBM8A is rare. Compound heterozygosity for this variant and a los s-of-function variant in RBM8A is strongly associated with TAR syndrome. Note th at individuals that are homozygous for this variant are not expected to have fea tures of TAR syndrome. In summary, this variant is pathogenic for TAR syndrome i n an autosomal recessive manner. ACMG/AMP Criteria applied: PS3, PM3_VeryStrong. -

Apr 19, 2023

Institute of Human Genetics, University of Leipzig Medical Center

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was identified as hemizygous in trans with a 414kb Deletion causative for the TAR Syndrome._x000D_ Criteria applied: PM3_VSTR, PS3, PP4 -

Apr 25, 2023

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: RBM8A c.67+32G>C is located at a position not widely known to affect splicing. 4/4 computational tools predict no significant impact on normal splicing. The variant allele was found at a frequency of 0.0055 in 234162 control chromosomes in the gnomAD database, including 8 homozygotes. Homozygotes in this variant are not expected to have features of TAR due to compound inheritance mechanism of this disease. c.67+32G>C has been reported to segregate with disease in the literature in multiple individuals affected with Radial Aplasia-Thrombocytopenia Syndrome, combined with a 1q21.1 deletion (Albers_2012). These data indicate that the variant is very likely to be associated with disease. Experimental studies suggest a reduced expression of the RBM8A protein and possibly disrupting a transcription factor binding site (Albers_2012). Nine clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as pathogenic (n=8) and likely pathogenic (n=1). Based on the evidence outlined above, the variant was classified as pathogenic. -

Apr 13, 2022

Fulgent Genetics, Fulgent Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided Pathogenic:8

Apr 19, 2024

Mayo Clinic Laboratories, Mayo Clinic

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

BS1, BS2, PM3_very_strong, PS3, PS4_supporting -

Jan 26, 2016

Eurofins Ntd Llc (ga)

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Nov 22, 2024

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Observed multiple times with a null pathogenic variant on the opposite allele (in trans) in unrelated patients with TAR syndrome in the published literature (PMID: 22366785, 28857120); Published functional studies suggest a damaging effect due to disruption of a transcription factor binding site and reduced expression of the resulting protein, consistent with a hypomorphic allele (PMID: 22366785); In silico analysis supports that this variant does not alter splicing; This variant is associated with the following publications: (PMID: 30609409, 27320760, 34906519, 22366785, 30385887, 27348543, 32109542, 32227665, 34958143, 36077017, 28857120) -

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Diagnostic Laboratory, Department of Genetics, University Medical Center Groningen

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Oct 23, 2020

Institute of Medical Genetics and Applied Genomics, University Hospital Tübingen

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Dec 24, 2022

Genomic Research Center, Shahid Beheshti University of Medical Sciences

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

-

Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Feb 16, 2025

Laboratory of Genetics, Children's Clinical University Hospital Latvia

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Global developmental delay;C1850049:Clinodactyly of the 5th finger;C4021085:Abnormal brain morphology Pathogenic:1

Feb 22, 2019

Knight Diagnostic Laboratories, Oregon Health and Sciences University

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

RBM8A-related disorder Pathogenic:1

Aug 20, 2024

PreventionGenetics, part of Exact Sciences

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

The RBM8A c.67+32G>C variant is predicted to interfere with splicing. The c.67+32G>C substitution is found in apparently unaffected individuals at frequencies over 0.5%. However, significant evidence suggests the c.67+32G>C substitution is a “functional polymorphism” and is likely a cause of disease only when paired with a null RBM8A allele, such as a large 1q21.1 deletion that encompasses the RBM8A gene. Large RBM8A deletions found in trans with a functional polymorphism such as c.67+32G>C have been identified in many patients with autosomal recessive thrombocytopenia with absent radius (TAR) (Albers et al. 2012. PubMed ID: 22366785; Boussion et al. 2020. PubMed ID: 32227665). Therefore, we consider this variant to be likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.36
CADD	Benign	16
DANN	Benign	0.72
PhyloP100		0.83
PromoterAI		-0.013	Neutral

Splicing

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

Other links and lift over

dbSNP: rs201779890; hg19: chr1-145507765;