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  • Gene obtained from curated document aligns with the Allele Registry but not with ClinVar data


Variant: NM_000174.5(GP9):c.466G>A (p.Ala156Thr)

CA202222

196227 (ClinVar)

Gene: GP9
Condition: Bernard-Soulier syndrome
Inheritance Mode: Autosomal recessive inheritance
UUID: 05e16eb5-5bb2-4243-b0b3-5cc2381f8cf5
Approved on: 2025-02-11
Published on: 2025-02-17

HGVS expressions

NM_000174.5:c.466G>A
NM_000174.5(GP9):c.466G>A (p.Ala156Thr)
NC_000003.12:g.129062205G>A
CM000665.2:g.129062205G>A
NC_000003.11:g.128781048G>A
CM000665.1:g.128781048G>A
NC_000003.10:g.130263738G>A
NG_008715.1:g.6404G>A
ENST00000307395.5:c.466G>A
ENST00000307395.4:c.466G>A
NM_000174.4:c.466G>A
More

Benign

Met criteria codes 3
BP4 PS3_Supporting BA1
Not Met criteria codes 4
BP2 PP4 PM3 BS2

Evidence Links 1

Expert Panel

Criteria Specification Information

Criteria Specification: ClinGen Platelet Disorders Expert Panel Specifications to the ACMG/AMP Variant Interpretation Guidelines for GP9 Version 1.0.0

Criteria Specification Approval History
Criteria Specifications for this VCEP
Evidence submitted by expert panel
Platelet Disorders VCEP
The c.466G>A (p.Ala156Thr) variant in GP9 is a missense variant predicted to cause substitution of alanine by threonine at amino acid 156. At least one patient (Case in PMID:15351858 or internal) with this variant had aggregation absent for ristocetin and present for all other agonists, which is highly specific for Bernard-Soulier syndrome. Additionally, the patient had excessive mucocutaneous bleeding and macrothrombocytopenia which is consistent with Bernard-Soulier syndrome, however this variant has a Grpmax Filtering allele frequency in gnomAD v4.1 is 0.2194 (based on 9530/42710 alleles) in the East Asian population, which is higher than the ClinGen PD VCEP threshold (>0.001), and therefore meets this criterion (BA1). The computational predictor REVEL gives a score of 0.187, which is below the ClinGen PD VCEP threshold of <0.290 and predicts no damaging effect on GP9 function and splicing predictor SpliceAI predicts no impact on splicing with delta scores of 0.00 (BP4). Surface expression of GPIBa and GP9 measured by flow cytometry in CHO cells in cells transiently co-transfected with the c.466G>A variant and wild type GP1a and GP1b showed decreased expression at very low (<25%) WT levels, indicating that this variant impacts protein function (PMID:15351858)(PS3_supporting). In summary with BP4 (-1), BA1, PS3_supporting (+1), the other criteria cancel out and BA1 alone provides a Benign classification, ACMG/AMP criteria applied, as specified by the ClinGen PD VCEP.
Met criteria codes
BP4
The computational predictor REVEL gives a score of 0.187, which is below the ClinGen PD VCEP threshold of <0.290 and predicts no damaging effect on GP9 function and splicing predictor SpliceAI predicts no impact on splicing with delta scores of 0.00 (BP4).
PS3_Supporting
Surface expression of GPIBa and GP9 measured by flow cytometry in CHO cells in cells transiently co-transfected with the c.466G>A variant and wild type GP1a and GP1b showed decreased expression at very low (<25%) WT levels, indicating that this variant impacts protein function (PMID:15351858)(PS3_supporting).

BA1
The Grpmax Filtering allele frequency in gnomAD v4.1 is 0.2194 (based on 9530/42710 alleles) in the East Asian population, which is higher than the ClinGen PD VCEP threshold (>0.001), and therefore meets this criterion (BA1).
Not Met criteria codes
BP2
This variant has been observed in cis with the variant c.450G>A (p.Trp150Ter) (PMID:20497174) which is classified as likely pathogenic by the ClinGen PD VCEP in an individual with Bernard-Soulier syndrome. The phase of the variants was confirmed by parental/family testing. Because p.Trp150Ter is not classified as pathogenic, this criteria is not met.
PP4
At least one patient (Case in PMID:15351858) with this variant had aggregation absent for ristocetin and present for all other agonists, which is highly specific for Bernard-Soulier syndrome (PP4). Additionally, the patient had excessive mucocutaneous bleeding and macrothrombocytopenia which is consistent with Bernard-Soulier syndrome. This is not considered here because BA1 is met.
PM3
Not evaluated for variants meeting BA1 or BS1.
BS2
This variant has been observed in 1 homozygous individual who is unaffected with Bernard Soulier Syndrome (proven with flow cytometry and normal platelet count and normal platelet size), a condition with high penetrance at an early age (PMID:20497174) Because the group threshold is >1 unaffected probands, this criteria is not met. CONFIRM HOMOZYGOSITY - CONFLICTING INFO IN PAPER
Curation History
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