Molecular genetics and metabolism最新文献

Gaucher disease (GD) is a rare genetic disorder with multi-system involvement. Liver fibrosis is a long-term complication of GD, potentially leading to cirrhosis, end-stage liver disease, and hepatocellular carcinoma. There are currently no validated clinical tools for the monitoring of liver fibrosis in patients with GD. In this study, we aim at assessing the validity of common fibrosis-predicting scores, developed for other diseases, for the use in GD, using transient elastography as a gold-standard, as well as developing the first GD-specific liver fibrosis predicting score. We enrolled 19 adult patients with GD who had been on treatment for a minimum of 1 year on enzyme replacement therapy or substrate reduction therapy and who had no evidence of any other liver disease except GD or metabolic-associated steatotic liver disease (MASLD), which is a common comorbidity of GD. We analyzed the correlation between liver stiffness and genotype, treatment modality (imiglucerase or other therapies), clinical severity, and clinical laboratory tests. We found that the common liver fibrosis scores APRI, FIB-4, and NFS did not accurately predict liver fibrosis in people with GD. We also found that male sex, the DS3 score, AST, and GGT levels significantly correlated with liver stiffness, and used these to create a simple but accurate fibrosis-predicting score specifically for GD (the "Gaucher liver fibrosis score", or GLFS), with high accuracy (AUC = 0.8571, p = 0.0206). We believe that our new GLFS may be used in clinical practice to help prioritize GD patients for closer monitoring of liver fibrosis.

Measurement of enzymatic activity in newborn dried blood spots (DBS) is the preferred first-tier method in newborn screening (NBS) for mucopolysaccharidosis (MPS) disorders. However, false positives are observed due mainly to the presence of pseudodeficiencies. Our previous publications on glycosaminoglycan (GAG) biomarker levels in dried blood spots (DBS) for mucopolysaccharidoses demonstrated that second-tier GAG biomarker analysis can dramatically reduce the false positive rate in NBS. In the present study, we extend this approach to the analysis of a large number of false positives for MPS-I obtained from the Illinois, New York, and Tennessee NBS programs and from Greenwood Genetics Center. Results show that GAG levels measured by the Endogenous-Non-Reducing End method (Endogenous-NRE) are in the normal reference range for all samples. In a second study, we analyzed 166 samples that showed below-cutoff MPS-I enzymatic activity level after testing 384,144 newborns in the Ontario, Canada NBS program. Both genotype and Endogenous-NRE GAG levels were determined for all 166 samples. Newborns at high risk for MPS-I based on genotype also showed elevated GAG levels and were clinically confirmed to be symptomatic for MPS-I. All newborns with pseudodeficiency or carrier status by genotyping all showed normal levels of the appropriate GAG biomarker. Samples found to be inconclusive based on one or more variants of unknown significance (VUS) all showed normal GAG biomarker levels and were found to be clinically normal during follow-up. These studies show that the Endogenous-NRE GAG second-tier NBS method is preferred over second-tier DNA analysis for the NBS of MPS-I with minimal false positives.

Background: Newborn screening (NBS) is a simple, non-invasive test that allows for the early identification of genetic diseases within the first days of a newborn's life. The aim of NBS is to detect potentially fatal or disabling conditions in newborns as early as possible, before the onset of disease symptoms. Early diagnosis enables timely treatments and improves the quality of life for affected patients.

Results: A pilot project for dried blood spot (DBS) NBS of lysosomal storage diseases (LSDs), including Mucopolysaccharidosis I (MPSI, IDUA α-L-iduronidase deficiency), Pompe disease (GAA α-glucosidase acid deficiency), Gaucher disease (GBA β-glucosidase deficiency) and Fabry disease (GLA α-galactosidase deficiency), was conducted using the digital microfluidic (DMF) technique. DBS were analyzed in a multiplexed assays for the enzymatic activities of four lysosomal enzymes (IDUA, GAA, GBA, GLA), and subjects identified as deficient in any of these enzymes were referred to the clinical reference center for diagnosis confirmation. From June 6th, 2022, to May 12th, 2023, a total of 7650 newborns were analyzed and 1 subject affected by Pompe disease was identified together with two additional subjects, suspected of Pompe and Fabry disease respectively, for whom continued follow-up is mandatory to determine the phenotype.

Conclusions: The pilot project for DBS NBS of four LSDs in Campania Region validated the effectiveness of DMF method, established enzymatic activity cut-offs, and identified newborns referred to the clinical center for integrated diagnostics, including genetic analyses. The results suggest that this technique can effectively detect potentially affected newborns, who will require further diagnostic confirmation and clinical follow-up. This diagnostic flow chart provides the opportunity to initiate early treatments and improve LSD patients' life span.

Cerebrotendinous Xanthomatosis (CTX) is a treatable, inborn error of bile acids metabolism caused by pathogenic variants in CYP27A1. CTX is a multi-organ system disorder that progresses over decades. Clinical features include cerebellar dysfunction, pyramidal tract dysfunction, cognitive deficits and decline, peripheral neuropathy, chronic diarrhea, bilateral cataracts, and tendon xanthomas. Treatment is effective when started early, but diagnostic delays often result in individuals not being diagnosed until after the window of highest treatment efficacy. CTX is documented to occur in most global populations, however, no CTX-causing genetic variants have been reported in Ashkenazi Jews. We conducted a systematic review of every case of CTX reported in a person identified as Jewish and the specific CYP27A1 variants present. We also leveraged the Israeli Medical Genetics Database and the population genetics data resource gnomAD to identify CTX-causing alleles in Ashkenazi Jews. We found that there are three pathogenic CYP27A1 variants in the Ashkenazi Jewish population segregating at an appreciable frequency, with a gene carrier rate of 0.002 based on the gnomAD Ashkenazi Jewish data. One pathogenic variant appears only in the Ashkenazi Jewish group in gnomAD, which contains genetic data from across the globe. We compared the carrier frequency for CTX to the carrier frequencies for diseases that are commonly included in carrier screening for Ashkenazi Jews. These results show that CTX occurs in Ashkenazi Jews, and that both Sephardi and Ashkenazi Jews may benefit from newborn and carrier screening for CTX.

Background and objectives: Mitochondrial diseases are caused by defects in oxidative phosphorylation, with primary mitochondrial myopathies (PMM) being a subset where muscle involvement is predominant. PMM presents symptoms ranging from exercise intolerance to progressive muscle weakness, often involving ocular muscles, leading to ptosis and progressive external ophthalmoplegia (PEO). PMM can be due to variants in mitochondrial or nuclear DNA. Growth differentiation factor 15 (GDF15) has been identified as an accurate biomarker for mitochondrial dysfunction. This study evaluates the utility of GDF15 as a biomarker for monitoring PMM.

Methods: This observational study involved 50 adult PMM patients. Clinical data were collected alongside functional motor outcomes measured by the Motor Research Council scale, 6-min walk test, North Star Ambulatory Assessment, and 100-m run test (100MRT). Biomarkers including serum lactate, creatine kinase (CK), creatinine, and plasma GDF15 were assessed.

Results: Patients exhibited diverse phenotypes, including exercise intolerance (8 %), progressive myopathy (22 %), isolated PEO (24 %), and PEO plus (42 %). Significant correlations were found among motor function tests, with 100MRT being particularly sensitive. Biomarker analysis showed elevated lactate in 32 %, elevated CK in 54 %, reduced creatinine in 76 %, and elevated GDF15 in 86 % of cases. GDF15 levels correlated with motor performance, lactate levels, and mtDNA mutation load in muscle. Creatinine levels were strongly linked to disease severity.

Discussion: This study underscores the heterogeneity of PMM and the importance of reliable biomarkers. GDF15 was consistently elevated across all PMM phenotypes and genotypes, correlating well with disease severity. Reduced creatinine also emerged as a potential prognostic marker.

Objective: GM1 gangliosidosis is a rare lysosomal storage disorder characterized by the accumulation of GM1 gangliosides in neuronal cells, resulting in severe neurodegeneration. Currently, limited data exists on the brain volumetric changes associated with this disease. This study focuses on the late-infantile and juvenile subtypes of type II GM1 gangliosidosis, aiming to quantify brain volumetric characteristics to track disease progression.

Methods: Brain volumetric analysis was conducted on 56 MRI scans from 24 type II GM1 patients (8 late-infantile and 16 juvenile) and 19 healthy controls over multiple time points. The analysis included the use of semi-automated segmentation of the whole brain, ventricles, cerebellum, corpus callosum, thalamus, caudate, and lentiform nucleus. A generalized linear model was used to compare the volumetric measurements between the patient groups and healthy controls, accounting for age as a confounding factor.

Results: Both late-infantile and juvenile GM1 patients exhibited significant whole-brain atrophy compared to healthy controls, even after adjusting for age. Notably, the late-infantile subtype displayed more pronounced atrophy in the cerebellum, thalamus, and corpus callosum compared to the juvenile subtype. Both late-infantile and juvenile subtypes showed significantly higher ventricular volumes and a significant reduction in all other structure volumes compared to the healthy controls. The volumetric measurements also correlated well with disease severity based on clinical metrics.

Conclusions: The findings underscore the distinct brain volumetrics of the late-infantile and juvenile subtypes of GM1 gangliosidosis compared to healthy controls. These quantifications can be used as reliable imaging biomarkers to track disease progression and evaluate responses to therapeutic interventions.