Mutations in TAF8 cause a neurodegenerative disorder.

TAF8 is part of the transcription factor II D complex, composed of the TATA-binding protein and 13 TATA-binding protein-associated factors (TAFs). Transcription factor II D is the first general transcription factor recruited at promoters to assemble the RNA polymerase II preinitiation complex. So far disorders related to variants in 5 of the 13 subunits of human transcription factor II D have been described. Recently, a child with a homozygous c.781-1G>A mutation in TAF8 has been reported. Here we describe seven further patients with mutations in TAF8 and thereby confirm the TAF8 related disorder. In two sibling patients, we identified two novel compound heterozygous TAF8 splice site mutations, c.45+4A > G and c.489G>A, which cause aberrant splicing as well as reduced expression and mislocalization of TAF8. In five further patients, the previously described c.781-1G > A mutation was present on both alleles. The clinical phenotype associated with the different TAF8 mutations is characterized by severe psychomotor retardation with almost absent development, feeding problems, microcephaly, growth retardation, spasticity and epilepsy. Cerebral imaging showed hypomyelination, a thin corpus callosum and brain atrophy. Moreover, repeated imaging in the sibling pair demonstrated progressive cerebral and cerebellar atrophy. Consistently, reduced N-acetylaspartate, a marker of neuronal viability, was observed on magnetic resonance spectroscopy. Further review of the literature shows that mutations causing a reduced expression of transcription factor II D subunits have an overlapping phenotype of microcephaly, developmental delay and intellectual disability. Although transcription factor II D plays an important role in RNA polymerase II transcription in all cells and tissues, the symptoms associated with such defects are almost exclusively neurological. This might indicate a specific vulnerability of neuronal tissue to widespread deregulation of gene expression as also seen in Rett syndrome or Cornelia de Lange syndrome.

Pretreatment Neurofilament Light Chain Serum Levels, Early Disease Severity, and Treatment Response in Pediatric Multiple Sclerosis.

BACKGROUND AND OBJECTIVES: High disease activity and frequent therapy failure in pediatric multiple sclerosis (MS) make prognostic biomarkers urgently needed. We investigated whether serum neurofilament light chain (sNfL) levels in treatment-naive pediatric patients with MS are associated with early disease severity and indicate treatment outcomes. METHODS: A retrospective cohort study of patients seen in the Göttingen Center for MS in Childhood and Adolescence, Germany. Inclusion criteria were MS diagnosis according to the McDonald criteria, MS onset <18 years, and available pretreatment serum sample. sNfL levels were analyzed using a single-molecule array assay. Associations with clinical and MRI evidence of disease severity at sampling were evaluated using the Spearman correlations and nonparametric tests for group comparisons. Correlations between pretreatment sNfL and annualized relapse and new T2 lesion rate on first-line therapy, and odd ratios for switch to high-efficacy therapy were assessed. RESULTS: A total of 178 patients (116 women [65%]) with a mean sampling age of 14.3 years were included in the study. Pretreatment sNfL levels were above the ≥90th percentile reported for healthy controls in 80% of patients (median 21.1 pg/mL) and correlated negatively with age, but no correlation was seen with sex, oligoclonal band status, or body mass index. High pretreatment sNfL levels correlated significantly with a high number of preceding relapses, a shorter first interattack interval, a high T2 lesion count, and recent gadolinium-enhancing lesions. Of interest, sNfL levels reflected more strongly MRI activity rather than clinical activity. Pretreatment sNfL levels also correlated significantly with the relapse rate and occurrence of new/enlarging T2 lesions while on first-line injectable therapy. Odds of future therapy escalation increased from 0.14 for sNfL below 7.5 pg/mL to 6.38 for sNfL above 15 pg/mL. In patients with a recent relapse, higher sNfL levels were associated with poorer recovery 3 months after attack. DISCUSSION: The results of this study have 3 important implications: First, pretreatment sNfL levels are a valuable biomarker for underlying disease activity in pediatric patients with MS. Second, pretreatment sNfL levels in pediatric patients with MS have a predictive value for the response to first-line therapy and the necessity of future therapy escalation. Third, high sNfL levels during a relapse are associated with poor recovery in this age group.