Published online Feb 19, 2023. doi: 10.5498/wjp.v13.i2.75
Peer-review started: September 30, 2022
First decision: December 1, 2022
Revised: December 9, 2022
Accepted: January 16, 2023
Article in press: January 16, 2023
Published online: February 19, 2023
Processing time: 140 Days and 6.2 Hours
Major depressive disorder (MDD) is the most frequent reason of disabled people in the world, as reported by the World Health Organization. However, the diagnosis of MDD is mainly based on clinical symptoms.
The clinical, genetic, and molecular characteristics of two Chinese families with MDD are described in this study. There were variable ages of onset and severity in depression among the families. Both Chinese families had a very low pre-valence of MDD. The mitochondrial genomes of these pedigrees were sequenced and indicated a homoplasmic T3394C (Y30H) mutation, with the polymorphism located at a highly conserved tyrosine at position 30 of ND1. The analysis also revealed unique sets of mitochondrial DNA (mtDNA) polymorphisms orig-inating from haplogroups M9a3 and M9a.
This finding of the T3394C mutation in two unrelated depressed patients provides strong evidence that this mutation may have a part in the etiology of MDD. However, In these two Chinese families having the T3394C mutation, no functional mtDNA mutation was observed. Therefore, T3394C mutations are related with MDD, and the phenotypic manifestation of these mutations may be affected by changes in nuclear genes or environmental factors.
Core Tip: We characterized two Chinese families with suspected maternal transmission of major depressive disorder at the clinical, genetic, and molecular levels in the present study. Molecular investigation revealed that the T3394C mutation in the ND1 gene was present in these Chinese families.