These six novel variants were located in four genes, including c.547G > T (p.E183Ter) and c.948delA (p.E316Ter) in PAH (NM_000277.1) associated with PKU, c.628G > A (p.E228K) and c.79A > C (p.T27P) in ACADS (NM_000017.4) causing short-chain acyl-CoA dehydrogenase deficiency, c.1364G > C (p.R455P) in SLC25A13 (NM_014251.3) causing CD, and c.493A > C (p.T165P) in MCCC1 (NM_020166.5) causing 3MCC. Here, MCCC1 is linked to Cowden disease.