Galactose-1-phosphate Uridyltransferase Research Articles

Single-nucleus and spatial transcriptomics of paediatric ovary: Molecular insights into the dysregulated signalling pathways underlying premature ovarian insufficiency in classic galactosemia.

Classic galactosemia (CG) is an inborn error of galactose metabolism caused by mutations in the GALT gene. Premature ovarian insufficiency (POI) is a later complication that affects 80% of women with CG due to a significant decline in ovarian reserve (primordial follicle pool). The definite mechanisms underlying the early onset of POI in CG patients are not fully understood. In this study, we performed single-nucleus RNA sequencing (snRNA-seq) and spatial transcriptomics on ovary tissue biopsies from prepubertal girls diagnosed with CG to investigate dynamic changes in gene expression and altered signalling pathways in granulosa cells, oocytes, and stromal cells. We generated single-nucleus and spatial transcriptomics atlas of human ovaries from prepubertal girls diagnosed with and without CG. snRNA-seq profiling of the paediatric ovary revealed a diverse ovarian microenvironment with seven distinct major cell types. Our transcriptomic analysis revealed an increase in the expression of several endoplasmic reticulum stress and oxidative stress associated genes, which can promote apoptosis of granulosa cells in CG. PTEN/PI3K/AKT signalling, which is crucial for primordial follicle activation and survival was dysregulated as supported by upregulated PTEN transcripts and a significant reduction in phospho-AKT levels in the granulosa cells and oocytes. We also found a marked increase in expression of phospho-H2A.X, LC3A/B and CASP9 in the primordial follicles of CG ovaries suggesting DNA damage, autophagy, and accelerated follicular atresia. Furthermore, we noticed genes participating in extracellular matrix organisation, integrin and gap junction signalling, essential for structural support of the ovarian stroma were profoundly altered. Our findings provide molecular insights into the dysregulated cellular signalling pathways essential for primordial follicle growth and survival that can explain the etiology of POI in CG patients. This study has implications in the development of future therapeutic interventions to preserve ovarian function and promote femalereproductive health. Created a comprehensive single-nucleus transcriptomic atlas and spatial landscape of paediatric ovary tissue from prepubertal girls diagnosed with classic galactosemia (CG). Our transcriptomic analysis revealed activation of genes associated with ER-stress signalling, oxidative stress response and ATM signalling/DNA damage response as shown by significant increase in expression of p-EIF2A, p-H2A.X and LC3A/B in the primordial follicles of CG ovary. PTEN/PI3K/AKT signalling pathways was dysregulated evidenced by a significant reduction in phospho-AKT expression in the primordial follicles of CG ovary, suggesting impaired follicle activation and survival.

Genomic variants associated with inborn errors in carbohydrate metabolism in southwestern Colombia

Introduction: Carbohydrate Inborn Errors of Metabolism (IEMs) result from disruption of the catabolic or anabolic pathways of different carbohydrates, fructose, galactose and glycogen being the most common and belong to a heterogeneous group of disorders that may be inherited or may occur as a result of spontaneous genetic variants. In IEM, there are altered carbohydrate pathways, both catabolic and anabolic pathways, including fructose, galactose and glycogen metabolism, resulting in a heterogeneous group of disorders. However, data on these pathologies in Colombia are scarce. The aim of our study was to identify genomic variants associated with carbohydrate IEM in the southwestern Colombian population lacking clinical diagnosis. Results: We performed a cross-sectional study, sequencing 320 exomes and classifying variants according to standard guidelines. We identified 286 variants, including 206 new variants and 73 benign or probably benign variants. Notably, six variants in genes such as GALT, GAK1, ALDOB, GAA and SLC2A1 were of uncertain significance, and one pathogenic variant in the GALT gene was associated with classic galactosemia. Interestingly, 18% were intronic, 5% missense, 10% synonymous, and 67% unreported variants. Conclusions: These findings highlight the need for early diagnostic programs to implement targeted treatments, including transdisciplinary management to minimize morbidity and mortality. Genetic counseling and risk education are crucial, facilitating anticipatory and preventive medicine approaches, thus advancing precision medicine.

Measurement of temperature, pH and substrate levels on the activity of the Galactose-1-Phosphate Uridyltransferase enzyme

Galactose-1-phosphate uridyltransferase (GALT) is an important enzyme involved in galactose metabolism. Understanding the factors influencing GALT activity is critical to elucidate its physiological role and potential therapeutic implications in galactosemia. In developing new drugs, chicken intestine/liver powder can be used as an enzyme source, GALT, to treat galactosemia. Therefore, it is necessary to research the characterization of the GALT enzyme in chicken intestine and liver powder. In this study, we investigated the influence of temperature, pH, and substrate level on GALT enzyme activity using an experimental approach in vitro. The optimum pH extraction results show that the optimum pH for the extraction of the chicken intestine and liver GALT is pH 7, with activity values ​​of 0.47 units/mL and 0.3953 units/mL, respectively. The optimum temperature for the extraction of chicken intestine and liver GALT is 37℃ with substrate hydrolysis capabilities of 0.48 U/mL and 0.57 U/mL, respectively. Meanwhile, the optimum substrate content is 400x. These insights provide a valuable foundation for further research aimed at comprehensively understanding GALT function, developing targeted interventions for disorders of galactose metabolism, and possible application in the development of new drugs for galactosemia

Galactose-1-phosphate inhibits cytochrome c oxidase and causes mitochondrial dysfunction in classic galactosemia

Classic galactosemia is an inborn error of metabolism caused by mutations in the GALT gene resulting in the diminished activity of the galactose-1-phosphate uridyltransferase enzyme. This reduced GALT activity leads to the buildup of the toxic intermediate galactose-1-phosphate and a decrease in ATP levels upon exposure to galactose. In this work, we focused our attention on mitochondrial oxidative phosphorylation in the context of this metabolic disorder. We observed that galactose-1-phosphate accumulation reduced respiratory rates in vivo and changed mitochondrial function and morphology in yeast models of galactosemia. These alterations are harmful to yeast cells since the mitochondrial retrograde response is activated as part of the cellular adaptation to galactose toxicity. In addition, we found that galactose-1-phosphate directly impairs cytochrome c oxidase activity of mitochondrial preparations derived from yeast, rat liver, and human cell lines. These results highlight the evolutionary conservation of this biochemical effect. Finally, we discovered that two compounds - oleic acid and dihydrolipoic acid – that can improve the growth of cell models of mitochondrial diseases, were also able to improve galactose tolerance in this model of galactosemia. These results reveal a new molecular mechanism relevant to the pathophysiology of classic galactosemia - galactose-1-phosphate-dependent mitochondrial dysfunction - and suggest that therapies designed to treat mitochondrial diseases may be repurposed to treat galactosemia.

Restoring galactose metabolism without restoring GALT rescues both compromised survival in larvae and an adult climbing deficit in a GALT-null D. Melanogaster model of classic galactosemia.

Classic galactosemia (CG) is an autosomal recessive disorder that results from profound deficiency of galactose-1-phosphate uridylyltransferase (GALT), the middle enzyme in the highly conserved Leloir pathway of galactose metabolism. That galactose metabolism is disrupted in patients with CG, and in GALT-null microbial, cell culture, and animal models of CG, has been known for many years. However, whether the long-term developmental complications of CG result from disrupted galactose metabolism alone, or from loss of some independent moonlighting function of GALT, in addition to disrupted galactose metabolism, has been posed but never resolved. Here, we addressed this question using a GALT-null Drosophila melanogaster model of CG engineered to express uridine diphosphate (UDP)-glucose/galactose pyrophosphorylase (UGGP), a plant enzyme that effectively bypasses GALT in the Leloir pathway by converting substrates uridine triphosphate (UTP) plus galactose-1-phosphate (gal-1P) into products UDP-galactose plus pyrophosphate (PPi). While GALT and UGGP share one substrate (gal-1P) and one product (UDP-galactose), they are structurally and evolutionarily unrelated enzymes. It is therefore extremely unlikely that they would also share a moonlighting function. We found that GALT-null flies expressing UGGP showed not only partial rescue of metabolic abnormalities and acute larval sensitivity to dietary galactose, as expected, but also full rescue of an adult motor deficit otherwise seen in this model. By extension, these results may offer insights to the underlying bases of at least some acute and long-term complications experienced by patients with CG.

Galactokinase 1 is the source of elevated galactose-1-phosphate and cerebrosides are modestly reduced in a mouse model of classic galactosemia.

Classic galactosemia (CG) arises from loss-of-function mutations in the Galt gene, which codes for the enzyme galactose-1-phosphate uridylyltransferase (GALT), a central component in galactose metabolism. The neonatal fatality associated with CG can be prevented by galactose dietary restriction, but for decades it has been known that limiting galactose intake is not a cure and patients often have lasting complications. Even on a low-galactose diet, GALT's substrate galactose-1-phosphate (Gal1P) is elevated and one hypothesis is that elevated Gal1P is a driver of pathology. Here we show that Gal1P levels were elevated above wildtype (WT) in Galt mutant mice, while mice doubly mutant for Galt and the gene encoding galactokinase 1 (Galk1) had normal Gal1P levels. This indicates that GALK1 is necessary for the elevated Gal1P in CG. Another hypothesis to explain the pathology is that an inability to metabolize galactose leads to diminished or disrupted galactosylation of proteins or lipids. Our studies reveal that levels of a subset of cerebrosides-galactosylceramide 24:1, sulfatide 24:1, and glucosylceramide 24:1-were modestly decreased compared to WT. In contrast, gangliosides were unaltered. The observed reduction in these 24:1 cerebrosides may be relevant to the clinical pathology of CG, since the cerebroside galactosylceramide is an important structural component of myelin, the 24:1 species is the most abundant in myelin, and irregularities in white matter, of which myelin is a constituent, have been observed in patients with CG. Therefore, impaired cerebroside production may be a contributing factor to the brain damage that is a common clinical feature of the human disease.

A case report of classic galactosemia with a GALT gene variant and a literature review

BackgroundGalactosemia is an autosomal recessive disorder resulting from an enzyme defect in the galactose metabolic pathway. The most severe manifestation of classic galactosemia is caused by galactose-1-phosphate uridylyltransferase (GALT) deficiency, and this condition can be fatal during infancy if left untreated. It also may result in long-term complications in affected individuals.Case presentationThis report describes a patient whose initial clinical symptoms were jaundice and liver dysfunction. The patient’s liver and coagulation functions did not improve after multiple admissions and treatment with antibiotics, hepatoprotective and choleretic agents and blood transfusion. Genetic analysis revealed the presence of two variants in the GALT gene in the compound heterozygous state: c.377 + 2dup and c.368G > C (p.Arg123Pro). Currently, the variant locus (c.377 + 2dup) in the GALT gene has not been reported in the Human Gene Mutation Database (HGMD), while c.368G > C (p.Arg123Pro) has not been reported in the Genome Aggregation Database (GnomAD) nor the HGMD in East Asian population. We postulated that the two variants may contribute to the development of classical galactosemia.ConclusionsApplications of whole-exome sequencing to detect the two variants can improve the detection and early diagnosis of classical galactosemia and, more specifically, may identify individuals who are compound heterozygous with variants in the GALT gene. Variants in the GALT gene have a potential therapeutic significance for classical galactosemia.

Premature ovarian insufficiency in patients with galactosemia

Background. Galactosemia is a congenital disorder of carbohydrate metabolism caused by a defect in any of the enzymes of galactose metabolism. One of the long-term complications is premature ovarian insufficiency (POI), which is more common in patients with the c.563A>G (Q188R) mutation in the homozygous state in the galactose-1-phosphate uridylyltransferase (GALT) gene. At the same time, fertility factors may be higher in patients with POI caused by classical galactosemia (CG) compared with other causes of POI, which makes it difficult to resolve the issue of the need to use fertility preservation methods for this group of patients in the prepubescent period. Case report. This article describes two clinical observations of patients with CG who were diagnosed with hypergonadotropic hypogonadism. Patient A. was initiated hormone replacement therapy (HRT) at the age of 11, and according to the results of osteodensitometry, there is currently no decrease in bone mineral density. In patient C. at the age of 14, before the start of HRT, ovaries without pronounced follicular apparatus, osteopenia and osteoporosis were detected. The issue of the necessity and timing of the use of fertility preservation methods is being considered. Conclusion. Patients with CG are recommended to monitor hormonal profile indicators for timely administration of HRT. Cryopreservation of ovarian tissue should be considered as one of the options for maintaining fertility in patients with CG, taking into account that some of them still have the possibility of spontaneous pregnancy, despite the POI.

Jasmonates and Ethylene Shape Floridoside Synthesis during Carposporogenesis in the Red Seaweed Grateloupia imbricata.

Floridoside is a galactosyl-glycerol compound that acts to supply UDP-galactose and functions as an organic osmolyte in response to salinity in Rhodophyta. Significantly, the UDP-galactose pool is shared for sulfated cell wall galactan synthesis, and, in turn, affected by thallus development alongside carposporogenesis induced by volatile growth regulators, such as ethylene and methyl jasmonate, in the red seaweed Grateloupia imbricata. In this study, we monitored changes in the floridoside reservoir through gene expression controlling both the galactose pool and glyceride pool under different reproductive stages of G. imbricata and we considered changing salinity conditions. Floridoside synthesis was followed by expression analysis of galactose-1-phosphate uridyltransferase (GALT) as UDP-galactose is obtained from UDP-glucose and glucose-1P, and through α-galactosidase gene expression as degradation of floridoside occurs through the cleavage of galactosyl residues. Meanwhile, glycerol 3-phosphate is connected with the galactoglyceride biosynthetic pathway by glycerol 3-phosphate dehydrogenase (G3PD), monogalactosyl diacylglyceride synthase (MGDGS), and digalactosyl diacylglyceride synthase (DGDGS). The results of our study confirm that low GALT transcripts are correlated with thalli softness to locate reproductive structures, as well as constricting the synthesis of UDP-hexoses for galactan backbone synthesis in the presence of two volatile regulators and methionine. Meanwhile, α-galactosidase modulates expression according to cystocarp maturation, and we found high transcripts in late development stages, as occurred in the presence of methyljasmonate, compared to early stages in ethylene. Regarding the acylglyceride pool, the upregulation of G3PD, MGDGS, and DGDGS gene expression in G. imbricata treated with MEJA supports lipid remodeling, as high levels of transcripts for MGDGS and DGDGS provide membrane stability during late development stages of cystocarps. Similar behavior is assumed in three naturally collected thalli development stages-namely, fertile, fertilized, and fertile-under 65 psu salinity conditions. Low transcripts for α-galactosidase and high for G3PD are reported in infertile and fertilized thalli, which is the opposite to high transcripts for α-galactosidase and low for G3PD encountered in fertile thalli within visible cystocarps compared to each of their corresponding stages in 35 psu. No significant changes are reported for MGDGS and DGDGS. It is concluded that cystocarp and thallus development stages affect galactose and glycerides pools with interwoven effects on cell wall polysaccharides.

Whole-body galactose oxidation as a robust functional assay to assess the efficacy of gene-based therapies in a mouse model of Galactosemia

Despite the implementation of life-saving newborn screening programs and a galactose-restricted diet, many patients with Classic Galactosemia develop long-term debilitating neurological deficits and primary ovarian insufficiency. Previously, we showed that administration of human GALT mRNA predominantly expressed in the GalT gene-trapped mouse liver augmented the expression of hepatic GALT activity, which not only decreased galactose-1 phosphate (gal-1P) in the liver, but also peripheral tissues. Since each peripheral tissue requires distinct methods to examine the biomarker and/or GALT effect, this highlights the necessity for alternative strategies to evaluate the overall impact of therapies. In this study, we established that whole-body galactose oxidation (WBGO) as a robust, non-invasive, and specific method to assess the in vivo pharmacokinetic and pharmacodynamic parameters of two experimental gene-based therapies that aimed to restore GALT activity in a mouse model of Galactosemia. While our results illustrated the long-lasting efficacy of AAVrh10-mediated GALT gene transfer, we found that GALT mRNA therapy that target the liver predominantly is sufficient to sustain WBGO. The latter could have important implications in the design of novel targeted therapy to ensure optimal efficacy and safety.

Determination of The GALT Gene in Galactosemic Cataract Patients in Azerbaijan

Galactosemia is one of the genetic diseases that can be treated thanks to early detection by genetic screening test. Galactosemia is a hereditary metabolic disease. This disease is heterogeneous and controlled by GALT, GALK, GALE and GALM genes. The presented article is dedicated to galactosemic disease among Azerbaijani patients as a result of GALT (galactose-1-phosphate uridyltransferase) gene mutations. This study reviews discusses the type of cataracts associated with galactosemia. The genetics of galactosemic patients are evaluated and details of galactose metabolism are described. This study describes the results of the GALT gene analysis of two Azerbaijanian patients with Galactosemic cataract. In one of the patients the heterzygous form of the same mutation, and the homozygous form in the other patient were found. In this study, control and experimental groups were determined, and DNA extracted from the peripheral blood of patients belonging to both groups was subjected to PCR amplification according to standard protocols and sequenced by Sanger sequence method. The symptoms of the disease were reviewed in these patients. Patients presented with jaundice, diarrhea, vomiting, malnutrition, seizures, allergies and more cataracts in the neonatal period. Commonly, Cataract disease is idiopathic origin. Also, patients with cataracts may have an underlying genetic abnormality of galactose metabolism. Elevated levels of galactose and galactose-1-phosphate and absence of GALT activity were diagnosed in the studied patients. Early biochemical and molecular-genetic diagnosis and genetic counseling of patients and their family members are extremely important in the treatment of galactosemia. We selected 25 cataract patients aged 0-45 years and 25 age and sex-matched controls for the study. Blood samples taken from the experimental and control groups, were biochemically and then molecular-genetically analyzed. Mutations Q188R, K285N and N314D were investigated in patients. Of these mutations, only the N314D mutation was detected in two patients. Both heterozygous and homozygous forms of N314D mutation were detected.

Grip strength in patients with galactosemia and in a galactose-1-phosphate uridylyltransferase (GALT)-null rat model.

Classic galactosemia (CG) and clinical variant galactosemia (CVG) are allelic inborn errors of metabolism that result from profound deficiency, and near-profound deficiency, respectively, of galactose-1-P uridylyltransferase (GALT). Despite early detection and lifelong dietary restriction of galactose, which is the current standard of care, most patients with CG/CVG grow to experience a range of long-term developmental and other complications. One of the less well-understood complications of CG/CVG is decreased hand grip strength, as reported by Potter et al. (2013). Here, we confirm this phenotype in an independent cohort of 36 cases (4-18 years) and 19 controls (4-17 years), and further demonstrate that the grip strength deficit observed in cases may be secondary to growth delay. Specifically, we found that when grip strength of cases and controls in a new cohort recruited in 2022 was plotted by weight, rather than age, the difference between cases and controls for both sexes disappeared. Reanalyzing data from the original 2013 cohort, we found that differences in weight accounted for grip strength differences between cases and controls in girls and young women, but not in boys and young men. Finally, we tested whether a GALT-null rat model of CG also showed a grip strength deficit-it did-and again the difference between GALT-null and wild-type rats associated with differences in body mass. Combined, these results confirm that GALT deficiency is associated with a grip strength deficit in both young patients with CG/CVG and GALT-null rats, and further demonstrate that this phenotype may be secondary to growth delay, and therefore not evidence of a muscle abnormality.

Identification of genes in a genomic DNA sequence

Today, newer pyrosequencing methods have drastically cut the cost of sequencing and may eventually allow every person the possibility of personalized genome information. Being able to read how our genes are expressed offers the promise of advanced medical treatments, but it will certainly require considerable work to generate, understand, organize, and apply this massive amount of data to human disease. This study describes the results of the CFTR, MEFV, GALT, PAH, BCKDHB and DBT genes analysis of Azerbaijanian patients. The molecular diagnostics methods using specific primers to identify CFTR, MEFV, GALT, PAH, BCKDHB and DBT genes many mutations. A total 15 different mutations (R261Q, V245V, P281L, R241C, L385L, V399V, E280K, R261X, A434D, R176X, Ex6-96A> G, R241C, R243Q, R252Q, Y356X) and 2 different polymorphisms (Q232Q,V245V) were detected of the PAH gene. 4 different mutations (P325L, H132Q, Q334K, N314D ) were detected of the GALT gene, 6 different mutations (Phe508del, Phe508del/5T, R117H/R334W, R553X and 965 (T-C)) were found in the CFTR gene, polymorphisms (D102D, G138G, A165A, R202Q, R314R, G474G, G476G, D510D) were detected of the MEFV gene, 2 different mutations were found of the BCKDHB gene and one mutation detected of the DBT gene in patients from Azerbaijani population. To prophylaxis the phenylketonuria, galactosemia, maple syrup urine disease, cystic fibrosis disease and Fammilian Mediterranian Fever it is recommended to screen genetically newborns, to consult medical-genetically risky families, and to carry out prenatal diagnostics during pregnancies for those families.

Quantification of golgi dispersal and classification using machine learning models

The Golgi body is a critical organelle in eukaryotic cells responsible for processing and modifying proteins and lipids. Under certain conditions, such as stress, disease, or ageing, the Golgi structure alters. Therefore, understanding the mechanisms that regulate Golgi dispersion has significant research contributions to identifying disease. However, there is a lack of tools to quantify the Golgi dispersion datasets. In this paper, we aim to automate the process of quantification of Golgi dispersion and use extracted features to classify dispersed Golgi images from undispersed Golgi images using machine learning models. First, we collected confocal microscopy images of transiently transfected HeLa cells expressing Galactose-1-phosphate uridylyltransferase (GALT)- green fluorescent protein (GFP) to quantify Golgi dispersal and classification. For the quantification, we introduced automated image processing and segmentation by applying mean and Gaussian filters. Then we used Otsu thresholding on preprocessed images and watershed segmentation to refine the segmentation of dispersed Golgi particles. In the case of classification, we extracted features from the Golgi dispersal images and classified them into empty vector (EV) versus CARP1 ring mutant (CARP1 RM) and empty vector (EV) versus CARP1 wildtype (CARP1 WT) classes. Our approach used machine-learning models, including logistic regression, decision tree, random forest, Naive Bayes, k-Nearest Neighbor (KNN), and gradient boosting for dispersed Golgi image classification. The experiment results show that our quantification technique on Golgi dispersal images reached 65% classification accuracy when the system uses a gradient boosting classifier for EV vs. CARP1 WT classification. Furthermore, our approach achieved 65% classification accuracy using a random forest classifier for EV vs. CARP1 RM classification.

Classical Hereditary galactosemia: findings in patients and animal models.

Classic galactosemia is a rare inborn error of metabolism that affects the metabolism of galactose, a sugar derived from milk and derivates. Classic galactosemia is caused by variants of the GALT gene, which lead to absent or misfolded forms of the ubiquitously present galactose-1-phosphate uridylyltransferase enzyme (GALT) driving galactose metabolites to accumulate, damaging cells from neurons to hepatocytes. The disease has different prevalence around the world due to different allele frequencies among populations and its symptoms range from cognitive and psychomotor impairment to hepatic, ophthalmological, and bone structural damage. The practice of newborn screening still varies among countries, dairy restriction treatment is a consensus despite advances in preclinical treatment strategies. Recent clinical studies in Duarte variant suggest dairy restriction could be reconsidered in these cases. Despite noteworthy advances in the classic galactosemia understanding, preclinical trials are still crucial to fully understand the pathophysiology of the disease and help propose new treatments. This review aims to report a comprehensive analysis of past studies and state of art research on galactosemia screening, its clinical and preclinical trials, and treatments with the goal of shedding light on this complex and multisystemic innate error of the metabolism.

Jasmonates disrupt carrageenan synthesis during carposporogenesis in the red seaweed Grateloupia imbricata

In this study, we monitored changes in cell wall sulfated galactans in the red seaweed Grateloupia imbricata after the rapid (48 h) induction of cystocarp maturation and carpospore development by the volatile hormone methyl jasmonate (MEJA). Synthesis of sulfated galactans, carrageenans, which requires sulfated UDP galactose, was followed by expression analysis of genes encoding phosphoglucomutase (PGM), galactose-1-phosphate uridyltransferase (GALT), and those responsible for sulfate assimilation (S-transporter and sulfate adenylyltransferase, SAT). In addition, the expression of carbohydrate sulfotransferase and galactose-6-sulfurylase responsible for the addition and removal of sulfate groups to the galactans backbone were evaluated. Structural changes, such as thallus softening, were analyzed using Fourier-transformed infrared spectroscopy (FTIR) spectra, and ploidy was assessed using flow cytometry. The results showed downregulation of most of the genes encoding precursors or those in charge of transformation into sulfated hexoses for cell wall synthesis. Furthermore, alterations in the FTIR spectrum of carrageenan from MEJA-induced fertile thalli, such as the disappearance and flattening of absorption bands, were observed. The promptness of these events and the ploidy of thalli and spores seem to confirm the induction of mitotic production of haploid spores by MEJA.

Novel GALT variations and genetic spectrum in Turkish population with the correlation of genotype and phenotype.

Classic galactosemia (OMIM#230400) is an autosomal recessive inborn error of carbohydrate metabolism caused by a deficiency of the galactose-1-phosphate-uridyl-transferase enzyme encoded by the GALT gene. Even though a galactose-restricted diet efficiently resolves the acute complications, it is insufficient to prevent long-term complications regarding speech defects, intellectual functioning, premature ovarian failure, cataract, hepatomegaly, dysarthria, ataxia, and tremor. Seventy-seven patients who were genetically diagnosed with classic galactosemia were included in this cohort. Identified novel variants were classified based on their predicted effect on the GALT function. Further, potential genotype-phenotype correlations were investigated via statistical analysis. In total, 18 different sequence variants were identified, including four novels (c.200delG/p.(Arg67Profs* 19), c.533T>G/ p.(Met178Arg), c.708_709delGT/p.(Ser236Argfs* 30), c.467C>A/p.(Ser156* )). Jaundice was the most common short-term finding with 80% (61/77). Even with early diagnosis, intellectual disability is encountered with 36% (27/74) of the long-term complications. Patients with biallelic missense variants have a significantly higher prevalence of cataracts (OR: 17.9). Longitudinal observations showed attenuation of cataracts and hepatomegaly. This study has shown the GALT variation spectrum of the Turkish population with a 30-year retrospective cohort, submitting a significant contribution to the genotype/phenotype correlation in galactosemia. This study also highlights the cost-effective importance of Sanger sequencing in the diagnosis of single-gene metabolic diseases.

Development, optimization and validation of LC-MS/MS method for the determination of DBS GALT enzyme activity

Galactosemia is a carbohydrate metabolism disorder often caused by galactose-1-phosphate uridyl transferase (GALT) deficiency. Detecting GALT deficiency involves measuring intra-erythrocyte enzyme activity. We aimed to create a robust liquid chromatography-mass spectrometry (LC-MS/MS) method to assess GALT activity in dried blood spot (DBS) samples. We validated this method and compared it to the fluorometric approach. We investigated the impact of K2EDTA and lithium heparin tubes on enzyme activity to identify the best sample collection tube. We also assessed the reaction-stopping method. The developed approach employed [13C6]-galactose-1-phosphate as a substrate and UDP-N-acetylglycosamine as an internal standard (IS). The mean ± SD value for GALT activity of DBS samples was determined as 6.37 ± 1.96 μmol/gHb/hour. The linear range was 0.4–50 μM (2.4–310% of normal) in the DBS method. The % coefficient of variation (%CV) values were less than 15 for intra-day and inter-day repeatability studies. Over 90% recovery was achieved in recovery studies, and no ion suppression from matrix was detected. DBS samples were quite stable for 31 days under different storage conditions. Enzyme activity results reported as <3.5 U/g Hb by fluorometric method, were quantitatively determined for even very low concentrations by LC-MS/MS method.

Molecular Basis of Galactosemia

The presented article discusses the results of the genetic screening of galactosemia for the disease of genetic metabolism. The structure of primers used in molecular diagnostics of the GALT gene is shown. The newborn has pathogenic mutations. GALTc.563 A&gt;G (p.Gln 188 Arg). The A&gt;G substitution occurred at nucleotide 563 of exon 6 of the GALT gene. The results of enzymatic testing in leukocyte preparations were analyzed. The results of molecular genetic analysis of the GALT gene showed that the disease of galactosemia in the population of the country is extremely rare.

Treatable cause of leukodystrophy: Galactosaemia

Galactosaemia is a group of autosomal recessive metabolic disorders characterised by increased blood levels of galactose. It is characterised by cataracts, organomegaly, sepsis and developmental delay. We are reporting a case of galactosaemia presenting as a neurodegenerative disease with a leukodystrophy-like presentation. An 11-month-old boy born to a second-degree consanguineously married couple presented with developmental delay, vomiting, lethargy and refusal of feeds. Examination showed normocephaly, cataract, hepatomegaly and spasticity in all limbs with exaggerated deep tendon reflexes. Magnetic resonance imaging (MRI) of the brain was suggestive of diffuse hyperintensities in periventricular, subcortical and deep white matter on T2WI. Plasma galactose levels were high (3784.0 u M/L) and the RBC Galactose 1-Phosphate uridylyltransferase (GALT) enzyme was low (&lt;0.04). Genetic testing showed homozygous missense mutation c.428C&gt;T (p.Ser143Leu) in exon 5 of the GALT gene. For any child who presents with cataracts, hepatomegaly, developmental delay and leukodystrophy picture on an MRI of the brain, a treatable cause of galactosaemia should be considered.