Supplemental Table S1:

Case25: Female, Italy, age not specified

DiseaseAssertion: Glanzmann thrombasthenia

FamilyInfo: N/A

ParentalGenotype: N/A

CasePresentingHPOs: N/A

CaseHPOFreeText: Severe bleeding

CaseNotHPOs: N/A

CaseNotHPOsFreeText: N/A

ProteinExpression: <5% αIIbβ3 expression

PlateletAggregation: Absent platelet aggregation (all the information that is provided in Supp. Table S1)

CasePreviousTesting: Sanger sequencing of exons, splice sites and untranslated regions of the ITGA2B and ITGB3 genes was performed

Gene: ITGA2B

Variant: NM_000419.3:c.2051T>G (p.Leu684Arg)

LegacyVariant: N/A

ClinVar: N/A

CAiD: CA399799849

gnomAD: N/A

PreviouslyPublished: PMID: 21113249

Case9: Patient CM, gender, age and ethnicity not specified

DiseaseAssertion: Glanzmann thrombasthenia type I

FamilyInfo: N/A

ParentalGenotype: N/A

CasePresentingHPOs: N/A

CaseHPOFreeText: Bleeding symptoms were evaluated by examining available hospital records. Mild bleeders were defined as those who had minor symptoms, such as epistaxis or gum bleeds, and moderate bleeders suffered, in addition, from bleeding complications after surgery and trauma. Severe bleeders were defined as those with a history of spontaneous or life-threatening hemorrhages, such as gastrointestinal bleeding, or who had repeated episodes requiring platelet transfusion. See Table 1.

CaseNotHPOs: N/A

CaseNotHPOsFreeText: N/A

ProteinExpression: See Table 6

PlateletAggregation: See Table 6

CasePreviousTesting: To ascertain the mutations, we sequenced the coding regions of the αIIb and β3 subunits including the exon/intron boundaries

Gene: ITGA2B

Variant: NM_000419.3:c.2051T>G (p.Leu684Arg)

LegacyVariant: N/A

ClinVar: N/A

CAiD: CA399799849

gnomAD: N/A

Case8: Patient GE, gender, age and ethnicity not specified

DiseaseAssertion: Glanzmann thrombasthenia type I

FamilyInfo: N/A

ParentalGenotype: N/A

CasePresentingHPOs: N/A

CaseHPOFreeText: Bleeding symptoms were evaluated by examining available hospital records. Mild bleeders were defined as those who had minor symptoms, such as epistaxis or gum bleeds, and moderate bleeders suffered, in addition, from bleeding complications after surgery and trauma. Severe bleeders were defined as those with a history of spontaneous or life-threatening hemorrhages, such as gastrointestinal bleeding, or who had repeated episodes requiring platelet transfusion. See Table 1.

CaseNotHPOs: N/A

CaseNotHPOsFreeText: N/A

ProteinExpression: See Table 6

PlateletAggregation: See Table 6

CasePreviousTesting: To ascertain the mutations, we sequenced the coding regions of the αIIb and β3 subunits including the exon/intron boundaries

Gene: ITGA2B

Variant: NM_000419.3:c.2051T>G (p.Leu684Arg)

LegacyVariant: N/A

ClinVar: N/A

CAiD: CA399799849

gnomAD: N/A

Case#: patient 2

DiseaseAssertion: Glanzmann thrombasthenia

**FamilyInfo: **

ParentalGenotype: If noted by authors, annotate with the carrier status of each parent in regards to the variant(s) identified in the proband.

CasePresentingHPOs:

PlateletAggregation: absent platelet integrin αIIbβ3. Monolayer of spread platelets essentially devoid of fibrinogen binding but with high CD62P expression and phosphatidylserine exposure (Figure S1). Figure 5.

CaseHPOFreeText:

CaseNotHPOs:

**CaseNotHPOFreeText: **

ProteinExpression:

CasePreviousTesting:

**PreviouslyPublished: **

Gene: ITGA2B

**HGVS: **

**ClinVar: **

CAID:

**gnomAD: **

Gene: ITGA2B

**HGVS: ** NM_000419.5:c.2051T>G

**ClinVar: ** 1330350

CAID: CA399799849

**gnomAD: **