Hereditary polyneuropathy with optic atrophy due to PDXK variant leading to impaired Vitamin B6 metabolism.

PDXK encodes for a pyridoxal kinase, which converts inactive B6 vitamers to the active cofactor pyridoxal 5'-phosphate (PLP). Recently, biallelic pathogenic variants in PDXK were shown to cause axonal Charcot-Marie-Tooth disease with optic atrophy that responds to PLP supplementation. We present two affected siblings carrying a novel biallelic missense PDXK variant with a similar phenotype with earlier onset. After detection of a novel PDXK variant using Whole Exome Sequencing, we confirmed pathogenicity through in silico protein structure analysis, determination of pyridoxal kinase activity using liquid chromatography-tandem mass spectrometry, and measurement of plasma PLP concentrations using high performance liquid chromatography. Our in silico analysis shows a potential effect on PDXK dimer stability, as well as a putative effect on posttranslational ubiquitination that is predicted to lead to increased protein degradation. We demonstrate that the variant leads to almost complete loss of PDXK enzymatic activity and low PLP levels. Our patients' early diagnosis and prompt PLP replacement restored the PLP plasma levels, enabling long-term monitoring of clinical outcomes. We recommend that patients presenting with similar phenotype should be screened for PDXK mutations, as this is a rare opportunity for treatment.

Study of the mechanisms of crocetin-induced differentiation and apoptosis in human acute promyelocytic leukemia cells.

Crocetin, the major carotenoid in saffron, exhibits potent anticancer effects. However, the antileukemic effects of crocetin are still unclear, especially in primary acute promyelocytic leukemia (APL) cells. In the current study, the potential antipromyelocytic leukemia activity of crocetin and the underlying molecular mechanisms were investigated. Crocetin (100 µM), like standard anti-APL drugs, all-trans retinoic acid (ATRA, 10 µM) and As2 O 3 (arsenic trioxide, 50 µM), significantly inhibited proliferation and induced apoptosis in primary APL cells, as well as NB4 and HL60 cells. The effect was associated with the decreased expressions of prosurvival genes Akt and BCL2, the multidrug resistance (MDR) proteins, ABCB1 and ABCC1 and the inhibition of tyrosyl-DNA phosphodiesterase 1 (TDP1), while the expressions of proapoptotic genes CASP3, CASP9, and BAX/BCL2 ratio were significantly increased. In contrast, crocetin at relatively low concentration (10 µM), like ATRA (1 µM) and As 2 O 3 (0.5 µM), induced differentiation of leukemic cells toward granulocytic pattern, and increased the number of differentiated cells expressing CD11b and CD14, while the number of the immature cells expressing CD34 or CD33 was decreased. Furthermore, crocetin suppressed the expression of clinical marker promyelocytic leukemia/retinoic acid receptor-α ( PML/RARα) in NB4 and primary APL cells, and reduced the expression of histone deacetylase 1 ( HDAC1) in all leukemic cells. The results suggested that crocetin can be considered as a candidate for future preclinical and clinical trials of complementary APL treatment.

Personalised treatment of haematological malignancies through systems medicine based on single molecules in single cells.

Molecular diagnostics in haematological malignancies continues to advance towards more personalized treatment and accordingly demand is increasing for procedures providing quantitative analyses of heterogeneous tissue in malignancies. Circulating leukaemic cells are diverse and comprise discrete clonal populations arising from a common progenitor cell. Some of the current diagnostic techniques possess an attenuated dynamic quantitative range that prevents a clear comprehension of intercellular interactions. Quantitative measurements will facilitate an accurate appreciation of holistic cellular processes, assist with predictions pertaining to perturbations and reveal functional moieties that are truly a facet of the disease, and thus add to current biomarker discovery which often lack assessment of functional involvement in disease mechanisms and processes. This review focuses on quantitative studies related to peripheral blood and haematological malignancies. Data retrieval for either of these diseases is hampered by the high and unchartered degree of heterogeneity typically existing within clinical samples. The likelihood of analysis across single cell populations is highly probable in the near future. This will allow a patient to be readily screened for malignancies and assigned to a risk group based on a quantitative profile of a complex of molecules related to disease. The future analysis of molecular pathology based on detailed molecular dissection looks promising, requiring the integration of various disciplines encompassing morphology, genetics, expression profiling and new and evolving predictive modeling via systems medicine. From this detailed view into patient health, an increasingly personalized treatment plan can be administered, commencing with stratified medicine.