Journal of Inherited Metabolic Disease最新文献

Bone manifestations are one of the most prevalent complications in patients with Gaucher disease (GD). Bone involvement is evaluated by using imaging methods, and there are different scores to assess its severity. However, there are no biomarkers that allow us to predict these manifestations. In recent years, several miRNAs have been associated with bone involvement and postulated as excellent bioavailable biomarkers. This study aims to identify a miRNA expression profile from plasma exosomes and to associate it with the severity of bone involvement in patients with GD. This study included 60 untreated patients with GD with bone involvement, who were classified according to the S-MRI score into three groups: mild disease (MiBD; S-MRI < 5), moderate disease (MoBD; S-MRI: 5–11), or severe disease (SBD; S-MRI > 11). Plasma exosomes were purified, and miRNAs were extracted and identified by next-generation sequencing (NGS) technology. Differentially expressed miRNAs were validated by droplet digital PCR (ddPCR). In the patients' groups classified by S-MRI, the median ages (Q1–Q3) were: MiBD 19.0 (4.00–40.00), MoBD 40.5 (28.25–56.00), and SBD 37.5 (31.25–47.00) years. When comparing groups, we found 12 differentially expressed exosomal miRNAs. After validation, four miRNAs were identified as differentially expressed: hsa-miR-127-3p, hsa-miR-184, hsa-miR-197-3p, and hsa-miR-660-5p. Notably, hsa-miR-127-3p, hsa-miR-660-5p, and hsa-miR-184 were correlated with the presence of infarcts, necrosis, and the degree of infiltration into the spine, pelvis, and femur. These three miRNAs could serve as bioavailable biomarkers to assess bone disease in GD, and further revalidation with a higher number of patients.

The number of inherited metabolic diseases (IMDs) in newborn screening (NBS) programs has increased significantly in the past decades. For some of the IMDs included in NBS (e.g., tyrosinemia type I), there are clear and substantial health benefits of NBS, while for others (e.g., very long chain acyl CoA dehydrogenase deficiency and 3-methylcrotonyl CoA carboxylase 1 deficiency), this is less clear as NBS identifies individuals who are asymptomatic or have milder forms of the disease. Therefore, knowledge of the full disease spectrum (including later onset forms) is needed when setting diagnostic metabolite cut-offs for NBS. Insights into the clinical, genetic and biochemical characteristics of different patient subsets can be used to redefine NBS protocols to identify patients with more severe forms of the disease who are most likely to benefit from identification in the newborn period. These insights require life-long monitoring of individuals identified based on symptoms versus those identified by NBS to determine long-term health outcomes and quantify the benefits of NBS. Adult metabolic specialists should be included in the development of NBS programs to provide data from this long-term monitoring and to contribute specific knowledge about later onset phenotypes of the IMDs included in NBS programs. The goal should be to develop NBS programs that identify newborns that benefit from early disease detection and treatment, without increasing psychological, social and management burden for individuals who may develop disease in adulthood with milder phenotype or potentially even not at all.

Human alanine:glyoxylate aminotransferase (AGT) is a liver peroxisomal enzyme that metabolizes glyoxylate, the oxalate precursor, to glycine. AGT deficiency, due to recessive pathogenic changes in the AGXT gene, results in calcium oxalate accumulation and kidney stones, a condition known as primary hyperoxaluria type 1 (PH1). Most missense variants lead to PH1 by causing AGT misfolding, but their effects manifest differently based on the presence of two polymorphic variants, p.Pro11Leu (p.P11L) and p.Ile340Met (p.I340M), which are usually present in linkage disequilibrium and generate the minor haplotype. While the p.P11L substitution reduces AGT global stability and worsens the effects of pathogenic changes, the p.I340M exerts a stabilizing effect whose role on PH1 pathogenesis has never been elucidated. The p.Ile279Thr (p.I279T) variant is frequent in healthy populations (0.29%), mainly on the major allele, but we present data from six PH1 families (eight patients) suggesting p.I279T as a PH1 pathogenic allele. Interestingly, in these families, p.Thr279 is always associated with p.Leu11 and p.Ile340, thus with a split AGXT haplotype. Analysis of the effects of the p.I279T mutation by in silico predictions, biochemical analyses on purified proteins, and expression in two cellular models of disease (AGXT1-KO HepG2 and CHO cells) shows that it causes a folding defect that is exacerbated by p.P11L but mitigated by p.I340M, thus explaining why p.Thr279 is pathogenic just on the p.Leu11–p.Ile340 haplotype. These data indicate that genetic screenings for PH1 should document the AGXT haplotype, including its components, to obtain an accurate diagnosis and possible prognostic information.

Neurodegeneration in metachromatic leukodystrophy (MLD) may be preceded by systemic complications. Characterization of these features is critical to define barriers to early diagnosis and treatment eligibility for gene therapy. We utilized medical billing (claims) datasets and a natural history study to capture pre-diagnosis MLD-related events. MLD-related events (ICD-10-CM codes) were aggregated into system-based diagnosis clusters, and time to MLD diagnosis (TTD) computed for each organ-system diagnosis cluster. Differences in TTD distribution, instantaneous diagnosis hazard, and survival to MLD diagnosis were compared by sex and payor type. TTD and regression from onset of first symptoms were described using median and inter-quartile range. The claims dataset identified 174 MLD cases (diagnosis ≤ 6 years old) with 14 diagnosed within the first year of life. General neurologic concerns (n = 138; median 257 days pre-diagnosis), gastrointestinal (n = 137; 231 days), seizures (n = 48; 236 days), ophthalmologic (n = 46; 362 days), and language-related events (n = 41; 267 days) were common. Time to MLD diagnosis from onset of prodromal clusters was longer for children with non-commercial insurance: most prominent with seizures (survival logrank p value < 0.02) and non-degenerative neurological symptoms (survival logrank p value < 0.04). Similar findings were noted in our analysis of a second claims dataset. The natural history cohort demonstrated a similar pattern of prodromal disease features and delayed diagnosis. This study defines barriers to MLD diagnosis and highlights prodromal periods of pre-regression symptomatology, further supporting the need for early screening in this fatal disorder of childhood.