Next-generation sequencing of 32 genes associated with hereditary aortopathies and related disorders of connective tissue in a cohort of 199 patients.

PURPOSE: Heritable factors play an important etiologic role in connective tissue disorders (CTD) with vascular involvement, and a genetic diagnosis is getting increasingly important for gene-tailored, personalized patient management. METHODS: We analyzed 32 disease-associated genes by using targeted next-generation sequencing and exome sequencing in a clinically relevant cohort of 199 individuals. We classified and refined sequence variants according to their likelihood for pathogenicity. RESULTS: We identified 1 pathogenic variant (PV; in FBN1 or SMAD3) in 15 patients (7.5%) and ≥1 likely pathogenic variant (LPV; in COL3A1, FBN1, FBN2, LOX, MYH11, SMAD3, TGFBR1, or TGFBR2) in 19 individuals (9.6%), together resulting in 17.1% diagnostic yield. Thirteen PV/LPV were novel. Of PV/LPV-negative patients 47 (23.6%) showed ≥1 variant of uncertain significance (VUS). Twenty-five patients had concomitant variants. In-depth evaluation of reported/calculated variant classes resulted in reclassification of 19.8% of variants. CONCLUSION: Variant classification and refinement are essential for shaping mutational spectra of disease genes, thereby improving clinical sensitivity. Obligate stringent multigene analysis is a powerful tool for identifying genetic causes of clinically related CTDs. Nonetheless, the relatively high rate of PV/LPV/VUS-negative patients underscores the existence of yet unknown disease loci and/or oligogenic/polygenic inheritance.

Progranulin as a candidate biomarker for therapeutic trial in patients with ALS and FTLD.

The loss-of-function mechanism in progranulin (PGRN) mutation carriers makes PGRN an interesting target for upregulation as a therapeutic approach in neurodegenerative diseases like frontotemporal lobar degeneration. This gives rise to several questions: (1) how stable are PGRN levels in blood and cerebrospinal fluid (CSF) in follow-up? (2) Is it necessary to measure PGRN levels in CSF to monitor a therapeutic effect? Therefore, concentrations of PGRN were measured in paired CSF and serum samples of 22 patients with behavioural variant frontotemporal dementia, including one GRN mutation carrier (c.349+1G>C), 16 patients with amyotrophic lateral sclerosis and 17 non-neurodegenerative patients, which included 22 follow-up levels. PGRN levels of 14 patients with isolated dysfunction of the blood-CSF barrier were measured and PGRN was correlated with albumin quotients as a marker for blood-CSF barrier function. The intrathecal fraction of PGRN was calculated on the basis of CSF-to-serum ratios and hydrodynamic properties. Follow-up measurements of CSF and serum PGRN levels did not show any significant change in diagnostic groups. Mean PGRN levels are 35 times higher in blood than in CSF. However, the CSF-to-serum PGRN ratio does not correlate with the albumin quotient even in patients with severe impairment of the blood-CSF barrier. The calculated intrathecal fraction of CSF PGRN levels ranged between 80 and 90 %. Assuming that CSF PGRN is either brain-derived or transported from the vascular compartment via receptor mediated mechanisms, we propose that monitoring CNS specific effects of PGRN modulating drugs should be done in CSF.