Genotypes and clinical assessment
The two groups did not differ significantly in gender (Chi-square value = 1.9652; p value = 0.1610), age (t-value = -1.42; p value = 0.1711) or education (t-value = -1.20; p value = 0.243). Ten MT patients had common mutation of mtDNA. Four of them (Patient 1-4) harbored the A3243G base substitution in the tRNALeu resulting in MELAS syndrome (mitochondrial encephalopathy, lactic acidosis, stroke-like episodes), four patients (Patient 5-8) had the A8344G substitution in tRNALys. This mutation frequently causes MERRF (myoclonic epilepsy associated with ragged red fibers) syndrome. Patient 9 and 10 harbored the T8993G mutation in gene mitochondrial ATP synthase 6 gene which results in NARP syndrome (neuropathy, ataxia, retinitis pigmentosa), and four patients (Patient 11, 12, 13, 18) had common deletion of the mtDNA. MtDNA common deletion results in adult CPEO. Patient 14 had the A8332G base substitution in the tRNALys and Patient 15 had the A12770G substitution resulting in a Glu - Gly substitution in gene ND5. In case of Patient 16 and 17, a C-T base substitution at nucleotide 14771 was present resulting in Pro-Ser substitution in CYB gene. In the case of Patient 19 - beside the A2706G polymorphism which is responsible for linezolid-induced severe lactic acidosis - 14 single nucleotide polymorphisms associated with Leber Hereditary Optic Neuropathy (LHON) were present potentially exerting synergistic effect.
Medication for the mitochondrial disease comprised of Coenzyme Q10, Vitamin E and vitamin C [29
]. Some patients were taking psychiatric drugs at the time of the assessment. Monotherapies were clonazepam (Patient 7, 10, 14), sertraline (Patient 12), mirtazapine (Patient 13), aripiprazole (Patient 19), combination therapies were quetiapine and trazodone for Patient 16, clonazepam, sertraline and quetiapine for Patient 18. Anticonvulsant treatment was valproate for Patient 7 and 8, carbamazepine for Patient 14 and lamotrigine for Patient 16.
MtDNA and 5HTTLPR genotypes, clinical symptoms and medication of the MT group are summarized in Table .
MtDNA and 5TTLPR genotypes, clinical symptoms and medication of MT patients
In the HN group, 9 patients harbored a duplication (Charcot-Marie-Tooth phenotype, CMT), and one patient had a deletion (Hereditary Neuropathy with Liability to Pressure Palsy phenotype, HNPP) in the PMP22 gene.
PMP22 and 5HTTLPR genotypes, clinical symptoms and medications of the HN group are summarized in Table .
PMP22 and 5HTTLPR genotypes, clinical symptoms and medication of HN patients (control group)
Mean HAQ-DI score was 0.82 in the MT (range: 0-1.625) and 0.71 in the HN group (range: 0-1.625). Level of disability between the two groups did not differ significantly (p = 0.6076).
Significant difference was found in the GSI score (1.44 vs 0.46, p = 0.013) and the nine subscales of the SCL-90-R scale. These subscales were obsession-compulsion (p = 0.0079), interpersonal sensitivity (p = 0.0079), depression (p = 0.0309), anxiety (p = 0.0309), hostility (p = 0.0428), phobic anxiety (p = 0.0309), paranoid ideation (p = 0.0101) psychoticism (p = 0.0002) and additional items (p = 0.013). No significant difference was found between the two groups' somatization score (p = 0.0817).
BDI-SF and HDRS scores of the two groups also differed significantly (12.85 vs 4.40, p = 0.0309, and 15.62 vs 7.30, p = 0.0428, respectively). No correlation has been found between total scores of GSI, BDI and HDRS with HAQ-DI either in the MT or in the HN group as assessed by Pearson's correlation.
Results of the SCL-90-R, BDI-SF, HDRS and HAQ-DI are summarized in Table .
Comparison of SCL-90-R, BDI-SF, HDRS and HAQ-DI scores of MT and HN patients
A variety of psychiatric disorders was diagnosed with SCID-I, with a current diagnosis in 6 (31%), past diagnosis in 8 (42%), both past and current diagnosis in 5 (26%), a lifetime prevalence in 9 (47%) MT cases. Past or current major depressive disorder, dysthymia, bipolar II and adjustment disorder with depressed mood occurred in 2 MT cases while the past or current diagnosis of major depression with psychotic features, bipolar I, mixed anxiety-depressive disorder, postpartum depression and PTSD was explored in 1 MT case.
Eight MT patients were diagnosed with personality disorder representing 42% of the group. Three cases of avoidant and 2 cases of obsessive-compulsive personality disorder were diagnosed. In 3 cases, personality disorder not otherwise specified (NOS) was described referring to depressive personality in case of Patient 5 and mixed personality disorder in the cases of Patient 16 and 18.
Five MT patients (Patient 1, 5, 8, 16, 18) had both Axis I and II diagnosis. This subgroup also had mean BDI and GSI scores above the average of the entire MT group (BDI of 19.2 versus 12.85 and GSI of 2.29 versus 1.44).
Patient 5, 6, 9, 11, 12, 17 was free of somatic symptoms (indicated with a HAQ-DI score of 0) but only Patient 6 and 12 was free of psychiatric symptoms as well (although Patient 12 was on Sertraline 50 mg at the time of the assessment for subclinical anxiety). From this physically asymptomatic group Patient 5 and 11 was included in the statistical analysis (independent variables). They have higher BDI (15.5 versus 12.85) and GSI (1.66 versus 1.44) compared to the entire MT group.
Gender, age, results of the SCID interviews, together with the BDI-SF, GSI and HAQ-DI scores of the MT group are indicated in Table .
Gender, age, results of SCID-I and SCID-II, BDI-SF, GSI and HAQ-DI scores of MT patients
In the HN group, 3 patients (30%) had past and current psychiatric diagnosis. Two HN patients had lifetime prevalence of dysthymia, 1 HN patient had lifetime prevalence of major depression, bipolar II, adjustment disorder with depressed mood and alcohol abuse. No personality disorder was found. Somatically asymptomatic (HAQ-DI score of 0) HN patients were Patient 20 and 27 with a lower mean BDI and GSI than the HN group's average (0.5 versus 4.4 and 0.11 versus 0.46, respectively).
Gender, age, results of the SCID interviews, together with the BDI-SF, GSI and HAQ-DI scores of the HN group are shown in Table .
Gender, age, results of SCID-I and SCID-II, BDI-SF, GSI and HAQ-DI scores of HN patients