The c.1139A>C variant in MYOC is a missense variant predicted to cause substitution of Aspartic Acid by Alanine at amino acid 380 (p.Asp380Ala). The highest minor allele frequency of this variant was in the European (non-Finnish) genetic ancestry group of gnomAD (v4.1.0) = 0.00000085 (1 allele out of 1,179,992), which met the ≤ 0.0001 threshold set for PM2_Supporting in a genetic ancestry group of at least 10,000 alleles. The REVEL score = 0.97, which met the ≥ 0.932 threshold for PP3_Strong, predicting a damaging effect on MYOC function. The Asp380Ala protein had increased insolubility, instability and reduced secretion levels compared to wild type myocilin protein in these studies (PMIDs: 20334347, 21612213, 23129764, 16466712). The assays met the OddsPath threshold for PS3_Moderate (> 4.3), indicating that this variant did impact protein function. This protein has also been assessed in these other studies (PMIDs: 15069026, 24333014), however, the same level of evidence was not met. 31 segregations in 6 families, with juvenile or primary open angle glaucoma (JOAG or POAG), have been reported (PMIDs: 17893668, 9863594, 9832047), which fulfilled PP1_Strong (≥ 7 meioses in > 1 family). 7 probands with JOAG or POAG have been reported carrying this variant (PMIDs: 17893668, 9863594, 9832047), which met PS4_Moderate (≥ 6 probands). Two other missense variants (c.1138G>C, p.Asp380His, Grantham score = 81, ClinVar ID: 7961 and c.1139A>G, p.Asp380Gly Grantham score = 94, ClinVar ID: 1342964) in the same codon have been classified as likely pathogenic for juvenile open angle glaucoma by the ClinGen Glaucoma VCEP. The c.1139A>C, p.Asp380Ala variant has a higher Grantham score (= 126) than the previously classified amino acid changes, was not predicted to affect splicing as assessed with SpliceAI (≤ 0.2), and met PP3, meeting the conditions for PM5 to apply. In summary, this variant met the criteria to receive a score of 14 and to be classified as pathogenic (pathogenic classification ≥ 10, adapted from PMID: 32720330) for juvenile open angle glaucoma based on the ACMG/AMP criteria met, as specified by the ClinGen Glaucoma VCEP (v2.0.0, 5 Dec 2024): PP1_Strong, PP3_Strong, PS3_Moderate, PS4_Moderate, PM5, PM2_Supporting (PP3 and PM5 capped at 5 points).