The c.1142_c.1145dup variant in the PDHA1 gene is a frameshift variant in the final exon of PDHA1, which is predicted to escape nonsense mediated decay and result in amino acid truncation that removes less than 10% of the predicted protein product (PVS1_moderate PMID: 30192042). This variant is absent from population databases (PM2). This variant has been reported in several patients with presentations consistent with PDHA1-related disease in the literature. While this variant has been reported several times before, only five cases met criteria for scoring, including four assumed de novo cases in PMID: 10679936 and PMID: 20002461, and one maternity confirmed de novo case in PMID: 26865159. Several commercial testing laboratories (GeneDx, Illumina, and Ambry) have identified this variant was harbored by maternity confirmed de novo probands with presentations consistent with PDHA1-related disease (minimum of 3 and maximum of 6 probands- SCV001251622.1, SCV000252046.3, SCV000742395.2). Upon further review, the expert panel determined that while unable to confirm the identity of these patients, taken together these data in conjunction with the cases reported in the literature were sufficient to support elevating scoring to PS2_Very Strong per SVI de novo variant scoring criteria v1.0. PMID: 1779625 and PMID: 8504309 reported elevated pyruvate in the blood, and blood and CSF of the respective probands. PMID: 23021068 performed PDC activity assays < 3rd percentile in fibroblasts (PP4). In summary, this variant meets criteria to be classified as a pathogenic of PDHA1- related pyruvate dehydrogenase deficiency in an X-linked manner. PDHA1-specific ACMG/AMP criteria applied: (PVS1_moderate, PM2, PS2_Very Strong, PP4). This was reviewed with the PDHA1 expert panel on 4/6/2021 and approved on 4/18/2021.