Supplementary Tables 1 and 2 combined information:

Case17b: GT17b, Male, 15 years old, brother of GT17a

DiseaseAssertion: Glanzmann thrombasthenia

FamilyInfo: Available per supplementary table 1

ParentalGenotype: Parents are not consanguineous, no other genotype information available

CasePresentingHPOs: HP:0000978, HP:0000979, HP:0031364, HP:0000421, HP:0002239

(Bruising, purpura, ecchymosis, epistaxis, gastrointestinal bleeding)

CaseHPOFreeText: Post traumatic hemorrhage

CaseNotHPOs: N/A

CaseNotHPOsFreeText: N/A

ProteinExpression: Showed <5% of αIIbβ3 expression measured by flow cytometry

PlateletAggregation: Platelet aggregation showed no response to ADP and collagen but normal response to ristocetin

CasePreviousTesting: All exons from ITGA2B and ITGB3 genes were amplified by PCR using intronic primers. DNA sequencing was determined by Sanger sequencing.

Gene: ITGA2B

Variant: NM_000419.3:c.2671C>T (p.Gln891Ter)

LegacyVariant: N/A

ClinVar: N/A

CAiD: CA8602626 (p.Gln891Ter)

gnomAD: N/A

Supplementary Tables 1 and 2 combined information:

Case18: Gt18, Male, 20 years old

DiseaseAssertion: Glanzmann thrombasthenia

FamilyInfo: Available per Table 1; however, very minimal information

ParentalGenotype: Parents are consanguineous, no other genotype information available

CasePresentingHPOs: HP:0000421

(Epistaxis)

CaseHPOFreeText: N/A

CaseNotHPOs: N/A

CaseNotHPOsFreeText: N/A

ProteinExpression: Showed <5% of αIIbβ3 expression measured by flow cytometry

PlateletAggregation: Platelet aggregation showed no response to ADP and collagen but normal response to ristocetin

CasePreviousTesting: All exons from ITGA2B and ITGB3 genes were amplified by PCR using intronic primers. DNA sequencing was determined by Sanger sequencing.

Gene: ITGA2B

Variant: NM_000419.3:c.2671C>T (p.Gln891Ter)

LegacyVariant: N/A

ClinVar: N/A

CAiD: CA8602626 (p.Gln891Ter)

gnomAD: N/A

Supplementary Tables 1 and 2 combined information:

Case17a: GT17a, Female, 14 years old, sister of GT17b proband

DiseaseAssertion: Glanzmann thrombasthenia

FamilyInfo: Available per supplementary table 1

ParentalGenotype: Parents are not consanguineous, no other genotype information available

CasePresentingHPOs: HP:0000978, HP:0000979, HP:0031364, HP:0000421

(Bruising, purpura, ecchymosis, epistaxis)

CaseHPOFreeText: Post traumatic hemorrhage

CaseNotHPOs: N/A

CaseNotHPOsFreeText: N/A

ProteinExpression: Showed <5% of αIIbβ3 expression measured by flow cytometry

PlateletAggregation: Platelet aggregation showed a small response to ADP and collagen but normal response to ristocetin

CasePreviousTesting: All exons from ITGA2B and ITGB3 genes were amplified by PCR using intronic primers. DNA sequencing was determined by Sanger sequencing.

Gene: ITGA2B

Variant: NM_000419.3:c.799+2T>C and NM_000419.3:c.2671C>T (p.Gln891Ter)

LegacyVariant: N/A

ClinVar: N/A

CAiD: CA399805155 (c.799 +2 T>C) and CA8602626 (p.Gln891Ter)

gnomAD: N/A

Supplementary Tables 1 and 2 combined information:

Case26: GT26, Male, 13 years old

DiseaseAssertion: Glanzmann thrombasthenia

FamilyInfo: Not available per supplementary table 1

ParentalGenotype: Parents are not consanguineous, no other genotype information available

CasePresentingHPOs: HP:0000978, HP:0000979, HP:0031364

(Bruising, purpura, ecchymosis)

CaseHPOFreeText: N/A

CaseNotHPOs: N/A

CaseNotHPOsFreeText: N/A

ProteinExpression: Showed <5% of αIIbβ3 expression measured by flow cytometry

PlateletAggregation: Platelet aggregation showed no response to ADP and collagen but normal response to ristocetin

CasePreviousTesting: All exons from ITGA2B and ITGB3 genes were amplified by PCR using intronic primers. DNA sequencing was determined by Sanger sequencing.

Gene: ITGA2B

Variant: NM_000419.3:c.2333A>C (Gln778Pro) and NM_000419.3:c.2671C>T (p.Gln891Ter)

LegacyVariant: N/A

ClinVar: 225393 (p.Gln778Pro)

CAiD: CA290947544 (p.Gln778Pro) and CA8602626 (p.Gln891Ter)

gnomAD: MAF in East Asian population: 0.0001087 https://gnomad.broadinstitute.org/variant/17-42453691-T-G

Supplementary Tables 1 and 2 combined information:

Case4: GT4, Female, 22 years old

DiseaseAssertion: Glanzmann thrombasthenia

FamilyInfo: Not available per supplementary table 1

ParentalGenotype: Parents are consanguineous, no other genotype information available

CasePresentingHPOs: HP:0000978, HP:0000979, HP:0031364, HP:0000421, HP:0000225, HP:0000132

(Bruising, purpura, ecchymosis, epistaxis, gingival bleeding, menorrhagia)

CaseHPOFreeText: N/A

CaseNotHPOs: N/A

CaseNotHPOsFreeText: N/A

ProteinExpression: Showed <5% of αIIbβ3 expression measured by flow cytometry

PlateletAggregation: Platelet aggregation showed no response to ADP and collagen but normal response to ristocetin

CasePreviousTesting: All exons from ITGA2B and ITGB3 genes were amplified by PCR using intronic primers. DNA sequencing was determined by Sanger sequencing.

Gene: ITGA2B

Variant: NM_000419.3:c.2671C>T (p.Gln891Ter)

LegacyVariant: N/A

ClinVar: N/A

CAiD: CA8602626

gnomAD: N/A

Case#: Patient 8

DiseaseAssertion: Glanzmann thrombasthenia

FamilyInfo: Not provided

ParentalGenotype: Not provided

CasePresentingHPOs: (HP:0000421, Epistaxis)

PlateletAggregation: All patients had abnormal platelet aggregation studies prompting analysis of platelet glycoprotein expression by flow cytometry.

ProteinExpression: Flow cytometry, 11 of 12 patients with GT had reduced antibody binding to GPIIb/IIIa

CasePreviousTesting: Not provided

PreviouslyPublished: Not provided

Gene: ITGA2B

Variant: c.1750C>T, p. (R584X)

HGVS: NM_000419.5:c.1750C>T

ClinVar: 2892 https://www.ncbi.nlm.nih.gov/clinvar/variation/2892/

CAID: CA115834

gnomAD: PopMax = 0.00008834 https://gnomad.broadinstitute.org/variant/17-44380004-G-A?dataset=gnomad_r4

Variant: c.2671C>T, p. (Q891X)

HGVS: NM_000419.5:c.2671C>T

ClinVar: 953054 https://www.ncbi.nlm.nih.gov/clinvar/variation/953054/

CAID: CA8602626

gnomAD: PopMax = 0.000007390 https://gnomad.broadinstitute.org/variant/17-44375647-G-A?dataset=gnomad_r4

PMID: 33928629

Previously annotated and reported Probands: PMID: 29675921. New Functional Evidence.

CAID: CA8602626

Gene: ITGA2B

Variant: NM_000419.3:c.2671C>T (p.Gln891Ter)

FunctionalEvidence: For Q887X mutation: Knock-in mice generated using CRISPR/Cas9 displaed no spontaneous bleeding phenotypes. Platelet morphology cofirmed to be normal and comparable platelet numbers to WT mice. Mean bleeding time increased and platelet aggregation impaired compared to WT. ITGA2B mRNA levels low in KI mice.