Some hotspot variants were also observed in Suzhou patients, including c.791G > A in MATA1 gene for hypermethioninemia (MIM# 250850), c.158G > A in PAH gene for mild hyperphenylalaninemia (M-HPA; MIM# 261600), c.721C > T in PAH gene for PKU (MIM# 261600), c.852_855delTATG in SLC25A13 gene for citrullinemia type II (CTLN 2; MIM# 605814), c.639+2T > A in MCCC1 gene for 3- methylcroton acyl coenzyme A carboxylase deficiency (3-MCCD; MIM# 210200 and 210210), c.1400C > G in SLC22A5 gene for primary carnitine uptake defect (PCUD; MIM# 212140), and c1031A > G in ACADS gene for SCADD. The gene discussed is MCCC1; the disease is pulmonary arterial hypertension.