Neuropsychological Features of Children and Adolescents With Mitochondrial Disorders: A Descriptive Case Series

BACKGROUND

Mitochondrial disorders (MD) are metabolic diseases related to genetic mutations in mitochondrial DNA and nuclear DNA that cause dysfunction of the mitochondrial respiratory chain. Cognitive impairment and psychiatric symptoms are frequently associated with MD in the adult population. The aim of this study is to describe the neuropsychological profile in children and adolescents with MD.

METHODS

We prospectively recruited a sample of 12 children and adolescents between February 2019 and February 2020 in the Reference Center for Mitochondrial Disorders of Angers (France). Participants and their parents completed an anamnestic form describing socio-demographic data and completed the WISC-V (Wechsler Intelligence Scale for Children, 5th edition) and the Parent and Teacher forms of the BRIEF (Behavior Rating Inventory of Executive Function).

RESULTS

In our sample, the mean IQ (Intellectual Quotient) score was 87.3 ± 25.3. The score ranged from 52 to 120. Concerning executive functions, a significant global clinical complaint was found for parents (six times more than normal) and to a lesser extent, for teachers (among 3 to 4 times more). Levels of intelligence and executive functioning were globally linked in our cohort but dissociation remains a possibility.

CONCLUSION

The results of this study show that MD can be associated to neuropsychological disorders in children and adolescents, especially regarding the intelligence quotient and the executive function. Our study also highlights the need for regular neuropsychological assessments in individuals with MD and developing brains, such as children and adolescents.

Clinical and molecular delineation of PUS3-associated neurodevelopmental disorders

Biallelic variants in PUS3 have recently been recognized as a rare cause of neurodevelopmental disorders. Pseudouridine synthase-3 encoded by PUS3 is an enzyme important for modification of various RNAs, including transfer RNA (tRNA). Here we present the clinical and genetic features of 21 individuals with biallelic PUS3 variants: seven new and 14 previously reported individuals, where clinical features of two were updated. The clinical and genetic information were collected through collaborations or by literature search. All individuals were characterized by the local clinicians and the gene variants were identified by next generation sequencing (NGS) based methodologies. The clinical picture was dominated by global developmental delay, epilepsy, hypotonia and microcephaly. Gray sclera, which has previously been suggested to be a characteristic feature of PUS3-associated phenotypes, was reported in only seven individuals. The patients had some dysmorphic facial features, but a recognizable gestalt was not observed. In conclusion, homozygous and compound heterozygous PUS3 variants lead to a rare neurodevelopmental disorder. Further functional studies are necessary to understand involvement of PUS3 and tRNA biogenesis in normal and abnormal brain development.

Myoclonic dystonia phenotype related to a novel calmodulin-binding transcription activator 1 sequence variant

Intragenic rearrangements and sequence variants in the calmodulin-binding transcription activator 1 gene (CAMTA1) can result in a spectrum of clinical presentations, most notably congenital ataxia with or without intellectual disability. We describe for the first time a myoclonic dystonia-predominant phenotype associated with a novel CAMTA1 sequence variant. Furthermore, by identifying an additional, recurrent CAMTA1 sequence variant in an individual with a more typical neurodevelopmental disease manifestation, we contribute to the elucidation of phenotypic variability associated with CAMTA1 gene mutations.

[Evaluation of in vitro activity of ofloxacin against 73 strains of Chlamydia trachomatis isolated from gynecologic infections]

The in vitro activity of ofloxacin, levofloxacin, ciprofloxacin, doxycyclin, erythromycin and roxithromycin was determined against 73 recent clinical strains of Chlamydia trachomatis isolated from genital infections. The MICs 90% were: 0.4; 0.1; 1.6; 0.2; 1.6 and 0.1 mg/l respectively. 100% of strains were susceptible to ofloxacin, roxithromycin and doxycyclin. Erythromycin and ciprofloxacin had a lower in vitro activity against C. trachomatis.