Background: Mitochondrial membrane protein‐associated neurodegeneration (MPAN) is caused by pathogenic sequence variants in C19orf12. Autosomal recessive inheritance has been demonstrated. We present evidence of autosomal dominant MPAN and propose a mechanism to explain these cases.Methods: Two large families with apparently dominant MPAN were investigated; additional singleton cases of MPAN were identified. Gene sequencing and multiplex ligation‐dependent probe amplification were used to characterize the causative sequence variants in C19orf12. Post‐mortem brain from affected subjects was examined.Results: In two multi‐generation non‐consanguineous families, we identified different nonsense sequence variations in C19orf12 that segregate with the MPAN phenotype. Brain pathology was similar to that of autosomal recessive MPAN. We additionally identified a preponderance of cases with single heterozygous pathogenic sequence variants, including two with de novo changes.Conclusions: We present three lines of clinical evidence to demonstrate that MPAN can manifest as a result of only one pathogenic C19orf12 sequence variant. We propose that truncated C19orf12 proteins, resulting from nonsense variants in the final exon in our autosomal dominant cohort, impair function of the normal protein produced from the non‐mutated allele via a dominant negative mechanism and cause loss of function. These findings impact the clinical diagnostic evaluation and counseling.

Background: Mucopolysaccharidosis type I (MPS I) is a rare, recessively inherited lysosomal storage disorder, characterized by progressive multi‐systemic disease. It is caused by a reduced or absent alpha‐l iduronidase (IDUA) enzyme activity secondary to biallelic loss‐of‐function variants in the IDUA. Over 200 causative variants in IDUA have been identified. Nevertheless, there is a fraction of MPS I patients with only a single mutated IDUA allele detectable.Methods: As genetic testing of MPS I is usually based on sequencing methods, copy number variations (CNVs) in IDUA can be missed and therefore presumably remain underdiagnosed. The aim of this study was the detection of CNVs using an IDUA‐specific in house multiplex ligation‐dependent probe amplification (MLPA) assay.Results: A total of five unrelated MPS I patient samples were re‐analyzed after only a single heterozygous IDUA mutation c.979G>C (p.A327P), c.1469T>C (p.L490P), c.1598C>G (p.P533R), c.1205G>A (p.W402X), c.973‐7C>G (p.?) could be identified. We detected a novel splice site variant c.973‐7C>G (p.?), as well as two novel CNVs, a large deletion of IDUA exon 14 and 3’UTR c.(1828 + 1_1829‐1)_(*1963_?)del, and a large duplication extending from IDUA exon 2 to intron 12 c.(157 + 1_158‐1)_(1727 + 1_1728‐1)dup.Conclusion: Together with the CNVs we previously identified, a total of four pathogenic IDUA CNVs have now been reported.

The most common form of hereditary spastic paraplegia (HSP), SPG4 is caused by single nucleotide variants and microrearrangements in the SPAST gene. The high percentage of multi-exonic deletions or duplications observed in SPG4 patients is predisposed by the presence of a high frequency of Alu sequences in the gene sequence. In the present study, we analyzed DNA and RNA samples collected from patients with different microrearrangements in SPAST to map gene breakpoints and evaluate the mutation mechanism. The study group consisted of 69 individuals, including 50 SPG4 patients and 19 healthy relatives from 18 families. Affected family members from 17 families carried varying ranges of microrearrangements in the SPAST gene, while one individual had a single nucleotide variant in the 5′UTR of SPAST. To detect the breakpoints of the SPAST gene, long-range PCR followed by sequencing was performed. The breakpoint sequence was detected for five different intragenic SPAST deletions and one duplication, revealing Alu-mediated microhomology at breakpoint junctions resulting from non-allelic homologous recombination in these patients. Furthermore, SPAST gene expression analysis was performed using patient RNA samples extracted from whole blood. Quantitative real-time PCR tests performed in 14 patients suggest no expression of transcripts with microrearrangements in 5 of them. The obtained data indicate that nonsense-mediated decay degradation is not the only mechanism of hereditary spastic paraplegia in patients with SPAST microrearrangements.

Introduction: Automatic cytological analysis of cerebrospinal fluid (CSF) by Sysmex XN‐Series represents a convenient laboratory platform for quantitative examination of nucleated CSF cells (monomorphonuclear (MN), polymorphonuclear (PMN), high‐fluorescent (HF)). HF cells (HFC), a research laboratory parameter so far, seem to be associated with certain clinical patterns. Hence, we aimed to determine the diagnostic HFC value for different clinical categories in neurological settings.Methods: Morphological classification of automatically detected HFC was carried out using manual light microscopy. Automatic method precision for cell differentiation was evaluated in comparison. In 284 cases, multiple correlation strategies and mathematical disease modellings enabled an explorative analysis of HFC suitability for case stratification into the categories Hemorrhage, Inflammation, Neoplasia, other, and unknown.Results: Manual microscopic reevaluation revealed plasma cells, macrophages, and malignant cells being HFC correlates in 80% of automatically detected HFC. Method correlation for automatic and manual CSF cell differentiation approaches was 95%, yielding a negative bias of 4.3% for MN and positive bias of 0.4% and 3.9% for PMN and HF, respectively. When HFC were used as a “stand‐alone” predicting tool, diagnostic accuracy, specificity, and sensitivity depended on the clinical condition, ranging from > 0.5 up to > 0.7 for Hemorrhage, Inflammation, and Neoplasia. However, multiparametric correlation analyses combining laboratory CSF diagnostics and mathematical methods defined HFC as a relevant laboratory parameter for adequate clinical case stratification. With an expected random distribution of 25% for four clinical categories, almost 70% of cases were correctly classified when the HFC‐based mathematical algorithm was applied.Conclusion: HFC has significant diagnostic and/or predictive value for neurological diseases.

Article Simplified preanalytical laboratory procedures for therapeutic drug monitoring (TDM) in patients treated with high-dose methotrexate (HD-MTX) and glucarpidase was published on July 15, 2024 in the journal Clinical Chemistry and Laboratory Medicine (CCLM) (volume 0, issue 0).

Objectives: To prospectively evaluate the diagnostic value of atypical urothelial cells (Atyp.C), an automatically determined quantitative parameter of the Sysmex UF‐5000 urine particle analyser (Sysmex Corp., Kobe, Japan), as a non‐invasive biomarker for urothelial carcinoma (UC). Early diagnosis of UC remains challenging despite advances in diagnostic techniques. While non‐invasive urine cytology has high diagnostic value, clinical evidence for Atyp.C in urine remains unclear. Quantification of Atyp.C in urine may improve non‐invasive UC disease diagnostics. Patients and Methods: Urine samples from 234 patients who underwent invasive urological intervention for non‐malignant conditions (control group [CG]) or UC (intervention group [IG]) were considered. Based on histopathology, the IG was subclassified into low‐grade (LG) and high‐grade (HG) UC and was further grouped into non‐muscle‐invasive (non‐MI) and MI UC. Patients who received neoadjuvant chemotherapy were analysed separately. Atyp.C of ≥0.1 Atyp.C/μL were defined as positive and were automatically quantified using the Sysmex UF‐5000 urine particle analyser, which classifies epithelial cells with disproportionately high nucleic acid content relative to cell size. Smoking state, urinary tract infection (UTI), and micro‐/macrohaematuria, were evaluated as potential confounding factors. Receiver operating characteristic (ROC) analysis was performed to assess explorative diagnostic Atyp.C performance. Results: The Atyp.C concentration was higher in the IG than in the CG (mean [SEM] 0.53 [0.1] vs 0.29 [0.1] Atyp.C/μL; P = 0.004), with a sensitivity of 0.59. HGUC exhibited higher Atyp.C levels (mean [SEM] 0.85 [0.2] Atyp.C/μL, P < 0.001) and a sensitivity of 0.73. MI UC showed the highest Atyp.C concentrations (mean [SEM] 0.95 [0.4] Atyp.C/μL; P = 0.004) and sensitivity of 0.78. ROC analysis demonstrated the highest diagnostic accuracy for MI UC (area under the ROC curve = 0.75). ROC analysis was exploratory and lacked external validation. UTI was a significant confounder for Atyp.C quantification. Conclusion: The Atyp.C are elevated in HGUC, particularly in MI disease, supporting their potential as a non‐invasive diagnostic biomarker in UC condition.