Variants p.Q1236H and p.E1143G in mitochondrial DNA polymerase gamma POLG 1 are not associated with increased risk for valproate‐induced hepatotoxicity or pancreatic toxicity: A retrospective cohort study of patients with epilepsy

• Published in: Epilepsia (Copenhagen) Vol. 59; no. 11; pp. 2125 - 2136
• Main Authors: Hynynen, Johanna, Pokka, Tytti, Komulainen‐Ebrahim, Jonna, Myllynen, Päivi, Kärppä, Mikko, Pylvänen, Laura, Kälviäinen, Reetta, Sokka, Arja, Jyrkilä, Aino, Lähdetie, Jaana, Haataja, Leena, Mäkitalo, Anna, Ylikotila, Pauli, Eriksson, Kai, Haapala, Piia, Ansakorpi, Hanna, Hinttala, Reetta, Vieira, Päivi, Majamaa, Kari, Rantala, Heikki, Uusimaa, Johanna
• Format: Journal Article
• Language: English
• Published: 01.11.2018
• ISSN: 0013-9580; 1528-1167
• DOI: 10.1111/epi.14568

Summary Objective Previous studies have suggested that heterozygous variants p.Q1236H and p.E1143G in mitochondrial DNA polymerase gamma ( POLG 1 ) increase the risk for liver injury for patients on valproate ( VPA ) therapy. We assessed the prevalence of these common variants and seven other pathogenic mutations in POLG 1 and determined the occurrence of VPA ‐induced hepatotoxicity ( VHT ) or pancreatic toxicity in a cohort of patients with epilepsy. Methods Patients with epilepsy (N = 367) were retrospectively identified from medical record files and screened for mutations in POLG 1 . Patients who had received VPA monotherapy and carried either of the two variants, p.Q1236H or p.E1143G, without other pathogenic mutations in POLG 1 (n = 33, variant group) and patients without these variants (n = 28, nonvariant group) were included in the study. Clinical data on epilepsy, characteristics of VPA treatment, risk factors for VHT , laboratory data on liver and pancreas functions, and adverse effects were collected. Results A total of 122 patients had either the POLG 1 p.Q1236H (n = 99) or p.E1143G (n = 24) variant in the heterozygous or homozygous state. Transient liver dysfunction was identified in three (n = 33, 9.1%) variant group patients and in one (n = 28, 3.6%) nonvariant group patient ( P = 0.62). Mild to moderate elevations in liver enzymes were encountered in both groups. Furthermore, two patients on VPA polytherapy developed acute pancreatitis, and two pediatric patients with heterozygous p.Q1236H variants and mutations in IQSEC 2 and GLDC , respectively, had elevated levels of VPA metabolites in urine, elevated plasma glycine, and/or increased acylglycine excretion. Significance POLG 1 p.Q1236H and p.E1143G variants could not be identified as statistically significant risk factors for VHT or pancreatic toxicity. We suggest that VPA treatment could be suitable for patients who harbor these common variants in the absence of other pathogenic mutations in POLG 1 .