2-218660069-A-G

Variant names:

• chr2-218660069-A-G
• rs745861723
• ENST00000392109:c.-199A>G

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 3P and 1B. PM2 PP5 BP4

The NM_004328.5(BCS1L):​c.-226A>G variant causes a 5 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000329 in 152,166 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.000033 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: BCS1L NM_004328.5 5_prime_UTR
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:2
• Conservation: PhyloP100: 0.368

Genes affected

BCS1L (HGNC:1020): (BCS1 homolog, ubiquinol-cytochrome c reductase complex chaperone) This gene encodes a homolog of the S. cerevisiae bcs1 protein which is involved in the assembly of complex III of the mitochondrial respiratory chain. The encoded protein does not contain a mitochondrial targeting sequence but experimental studies confirm that it is imported into mitochondria. Mutations in this gene are associated with mitochondrial complex III deficiency and the GRACILE syndrome. Several alternatively spliced transcripts encoding two different isoforms have been described. [provided by RefSeq, Jan 2016]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 2-218660069-A-G is Pathogenic according to our data. Variant chr2-218660069-A-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 2680147.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=2}.
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.78). . Strength limited to SUPPORTING due to the PP5.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
BCS1L	NM_001079866.2	c.-50+326A>G		intron_variant	Intron 1 of 7	ENST00000359273.8	NP_001073335.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
BCS1L	ENST00000359273.8	c.-50+326A>G		intron_variant	Intron 1 of 7	1	NM_001079866.2	ENSP00000352219.3

Frequencies

GnomAD3 genomes AF: 0.0000329 AC: 5 AN: 152166 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000735

Gnomad OTH AF: 0.00

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 34 Hom.: 0 Cov.: 0 AF XY: 0.00 AC XY: 0 AN XY: 20

Gnomad4 AFR exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

GnomAD4 genome AF: 0.0000329 AC: 5 AN: 152166 Hom.: 0 Cov.: 32 AF XY: 0.0000269 AC XY: 2 AN XY: 74328

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000735

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.0000416

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Pili torti-deafness syndrome Pathogenic:1

Feb 27, 2024

Baylor Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not specified Uncertain:1

Apr 25, 2024

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

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: BCS1L c.-226A>G is located in the untranslated mRNA region upstream of the initiation codon. The variant allele was found at a frequency of 3.2e-05 in 31390 control chromosomes (gnomAD). c.-226A>G has been reported in the literature in individuals affected with features of Mitochondrial Complex III Deficiency, including renal tubulopathy and hepatopathy (Cruz_2017, Bick_2017), and these patients were reported as compound heterozygous with a pathogenic variant. These data indicate that the variant may be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publications have been ascertained in the context of this evaluation (PMID: 28128857, 28496993). ClinVar contains an entry for this variant (Variation ID: 2680147). Based on the evidence outlined above, the variant was classified as VUS-possibly pathogenic. -

Pili torti-deafness syndrome;C1864002:GRACILE syndrome;C3541471:Mitochondrial complex III deficiency nuclear type 1 Uncertain:1

Jun 19, 2024

Fulgent Genetics, Fulgent Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.78
CADD	Benign	13
DANN	Benign	0.70

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

LitVar

Other links and lift over

dbSNP: rs745861723; hg19: chr2-219524792;