RARE DISEASE
Classic galactosemia
Classic galactosemia
Classic galactosemia
Synonyms: GALT deficiency, Galactose-1-phosphate uridyltransferase deficiency, Galactosemia type 1
Synonyms: GALT deficiency, Galactose-1-phosphate uridyltransferase deficiency, Galactosemia type 1
Synonyms: GALT deficiency, Galactose-1-phosphate uridyltransferase deficiency, Galactosemia type 1
Drug discovery
1
drug
With orphan designation
Overview
Classic galactosemia is an autosomal recessive disorder caused by deficient galactose-1-phosphate uridylyltransferase (GALT) activity, impairing galactose metabolism. Neonatal presentation includes feeding difficulties, hepatic dysfunction, and sepsis risk without prompt dietary intervention. Lifelong galactose restriction prevents acute toxicity but fails to halt chronic complications: neurocognitive impairments, primary ovarian insufficiency (79.9% of females), and low bone density (26.5%) [1][2][6].
Burden
Clinical: 85% develop neurocognitive deficits (speech, memory), tremors, and social challenges; progressive functional decline [4][9][13].
Psychosocial: Caregiver dependency (67% adults require daily support), social isolation, and mental health impacts [4][5][13].
Economic: High costs of lifelong medical care, therapies, and dietary management [5][14].
Therapies
Dietary: Lifelong lactose-free formula (infancy) and strict galactose avoidance, though endogenous production persists [1][6][8].
Adjuncts: Calcium, vitamin D/K supplementation; developmental/gonadal monitoring [2][3][12].
Emerging therapies: GALT gene/mRNA therapy, GALK1 inhibitors, and pharmacological chaperones under investigation [1][16].
Categories: rare endocrine diseases, rare genetic diseases, rare gynecological and obstetric diseases, rare hepatic diseases, rare inborn errors of metabolism, rare infertility disorders, rare neurological diseases, rare ophthalmic disorders, rare renal diseases, rare transplant-related disorders
Research Papers
342 drug discovery papers about Classic galactosemia, with 4 first-in-class and 3 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
342 drug discovery papers about Classic galactosemia, with 4 first-in-class and 3 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
2025-11-21 | Experimental Galactose-1-Phosphate Uridylyltransferase (GALT) mRNA Therapy Improves Motor-Related Phenotypes in a Mouse Model of Classic Galactosemia—A Pilot Study
Background: Despite life-saving newborn screening programs and a life-long galactose-restricted diet, many patients with classic galactosemia continue to develop long-term debilitating neurological deficits, speech dyspraxia, and primary ovarian insufficiency (POI). In an earlier study, we showed that administration of an experimental human GALT mRNA predominantly expressed in the liver of the GalT gene-trapped mouse model augmented the expression of hepatic GALT activity, which reduced build-up of galactose and its toxic metabolites not only in the liver but also in the peripheral tissues. Moreover, we showed that the administration of GALT mRNA in the mutant mice restored whole-body galactose oxidation (WBGO), which is a functional biomarker. Methods: In this pilot study, we extended our proof-of-concept efficacy studies to a disease-relevant phenotype: motor impairment. GalT-KO mice aged 3 and 6 weeks old administered biweekly intravenous injections of 100 µL GALT mRNA at a dose of 2 mg/kg for 2 months. Motor performance was assessed using rotarod testing and composite phenotype scoring, 3 and 9 weeks following the dosing regimen. Results: Preliminary results showed that a biweekly dosing at 2 mg/kg for 2 months improved the motor performance of the animals in rotarod and composite phenotype scoring tests in a short-term experiment. Conclusions: Despite being a small-scale study, our findings suggest that when treated early in life, the experimental GALT mRNA is effective in improving the motor-related phenotypes in GalT-KO mice using the specified dosing regimen. These findings highlight the potential of mRNA-based therapies for mitigating neurological symptoms in Classic galactosemia.
2025-11-15 | Pretreatment With a Selected Strain of Baker's Yeast, GY007, Prevents the Accumulation of Galactose Metabolites Following Dietary Galactose Exposure in a GALT-Null Rat Model of Classic Galactosemia.
The current standard of care for patients with classic galactosemia (CG) involves lifelong dietary restriction of high galactose foods, including most dairy products. Here, we present the results of a pilot study testing whether pretreatment with GY007, a strain of baker's yeast selected to metabolize galactose despite the presence of other sugars, would be sufficient to prevent the metabolic impact of dietary galactose exposure in a GALT-null rat model of CG. Specifically, we dosed cohorts of adolescent GALT-null rats with either (a) placebo alone, (b) placebo followed by galactose, or (c) GY007 yeast followed by galactose. All rats were treated 3 times daily for 8 consecutive days, for a combined daily dose of almost 27 mg galactose per rat. Wild-type rats dosed with placebo served as controls. All rats also had ad libitum access to water and chow that contained about 0.15% calories from galactose. Rats grew at the expected pace for the duration of the study regardless of treatment group. To test the metabolic efficacy of the GY007 pretreatment, we followed galactose, galactitol, and gal-1P longitudinally in blood, and at euthanasia in brain and liver. In both liver and red blood cells, most metabolites remained near placebo levels despite the galactose exposure, limiting our ability to test the efficacy of GY007 pretreatment in those tissues. However, in both plasma and brain, metabolites showed a significant elevation following galactose exposure, and this rise was prevented by pretreatment with GY007. These results demonstrate the potential of GY007 yeast to prevent the metabolic consequences of transient low-level dietary galactose exposure in GALT deficiency.
2025-10-14 | Myo-Inositol Deficiency, Structural Brain Changes, and Cerebral Perfusion Alterations in Classic Galactosemia: Preliminary Insights From a Multiparametric MRI Study.
Classic galactosemia is a rare metabolic disorder resulting from galactose-1-phosphate uridylyltransferase deficiency, which disrupts normal galactose metabolism, leading to toxic accumulation of galactose-1-phosphate and galactitol. Despite early dietary intervention, patients remain at risk for long-term neurological impairments, including cognitive deficits, motor speech disorders, and psychiatric conditions. The mechanisms driving these persistent abnormalities remain unclear. This study investigated brain metabolic and structural alterations in adults with classic galactosemia using advanced multiparametric MRI. Six patients (3 males, 3 females; mean age 34.0 ± 7.3 years) adhering to lifelong galactose-restricted diets and six age- and sex-matched controls underwent 3T and 7T MRI, including T1-weighted imaging, pseudo-continuous arterial spin labeling, and high-resolution MR spectroscopic imaging. Patients exhibited significantly lower myo-inositol (mIns) concentrations in cerebellum (p = 0.007), putamen (p = 0.023), and cerebral white matter (p = 0.001), reflecting a chronic mIns deficiency despite dietary management. Structural analyses revealed reduced volumes of white matter (p < 0.001), bilateral putamen (p < 0.038), and left thalamus (p = 0.044); alongside increased cortical thickness and reduced cortical surface area, indicating abnormal cortical maturation, particularly in regions associated with motor and cognitive processing. Additionally, cerebral blood flow was elevated in emotion-processing regions, including bilateral amygdala (p < 0.022) and thalamus (p < 0.038). These preliminary findings highlight persistent neurological alterations in classic galactosemia despite dietary management and suggest that chronic mIns deficiency may contribute to the pathophysiology. They underscore the need for larger, longitudinal studies to confirm these results, investigate potential correlations with clinical severity and biochemical markers, and explore therapeutic strategies aimed at modulating mIns metabolism.
2025-10-01 | Exit interviews with caregivers of pediatric patients with classic galactosemia to explore meaningfulness of changes in the ACTION-galactosemia kids trial.
Classic Galactosemia is a rare, autosomal recessive disease in which galactose is not metabolized properly due to severe deficiency/absence of the galactose-1-phosphate uridylyltransferase (GALT) enzyme, converting to an aberrant and toxic metabolite, galactitol. Living with the debilitating symptoms and long-term consequences of Classic Galactosemia creates a heavy burden on patients' and their families' lives. Objectives were to: (1) Evaluate the impact and burden of disease; (2) Qualitatively explore changes in patient symptoms following treatment; and (3) Document the meaningfulness of changes resulting from treatment with govorestat as assessed by the Caregiver Global Impression of Severity (CGIS) and Caregiver Global Impression of Change (CGIC) scales. The AT-007-1002 clinical trial involved a Phase 1/2 dose escalation component (Part A) followed by a Phase 3, randomized, double-blind, placebo-controlled long-term administration component (Part B) that evaluated potential clinical benefit. Exit Interviews were completed prior to unblinding of data. The in-depth, qualitative interviews were semi-structured, using a discussion guide, and conducted by either Zoom or GoToMeeting. Thirty-six caregiver interviews were conducted, capturing the experience of 37 pediatric patients (one caregiver had 2 patients enrolled in the study). Thematic analysis was undertaken to identify themes or patterns within the data. All analyses were conducted on blinded data. Following finalization of the analysis and report findings, post-hoc analysis of the unblinded data was then conducted to explore the meaningfulness of patients experience by treatment arm. This study confirms the substantial burden known to be associated with Classic Galactosemia in a pediatric population. The difficulties experienced were across multiple areas including cognitive function, behavior/social function, motor function, emotional function, communication, vision problems, ovarian insufficiency, sensory difficulties, and sleep problems. The interviews demonstrated that most patients (approximately two thirds) experienced an improvement in symptoms and impacts associated with classic galactosemia over the course of the trial. Nearly all caregivers reported that they perceived a 1-category change on the Caregiver Global Impression of Severity or Caregiver Global Impression of Change items, indicating severity and change respectively, was meaningful to them and the patient. Unblinded analysis of the exit interview data confirmed the patient experience reported by caregivers was different between the treatment arms, providing qualitative support for the treatment benefit of govorestat when compared to placebo. Furthermore, the qualitative data from caregivers provide in-depth insights of their unique lived experience that highlight the substantial impact that this improvement had on the caregiver's and the patient's quality of life. The improvements observed led to a reduction on the burden of Classic Galactosemia and may lead to a greater patient's greater independence. The exit interviews confirmed the burden of Classic Galactosemia disease across multiple domains. Qualitative investigation suggests that observed changes are meaningful to the patient and caregiver, and changes were more commonly reported in those receiving govorestat compared to placebo. Full clinical trial findings will be published separately.
2025-07-14 | A Pilot Study of Bone Marrow Transplantation in a GALT-Null Rat Model of Classic Galactosemia.
Classic galactosemia (CG) is a rare inborn error of metabolism with substantial unmet medical need. Early detection, often by population newborn screening, enables immediate and life-long dietary restriction of galactose, which is the current standard of care. This treatment minimizes or prevents the potentially lethal acute symptoms of disease in infants but fails to prevent the long-term developmental complications experienced by most patients later in childhood. Many possible approaches to improved intervention have been proposed, ranging from small molecule inhibitors or effectors to chaperones to DNA or RNA-based gene therapy, among others. Here, we describe the results of a pilot study testing the potential efficacy of GALT+ bone marrow transplantation (BMT) as a candidate intervention in a GALT-null rat model of CG. Specifically, we pre-treated adolescent GALT-null rats with busulfan for myeloablation and then administered major histocompatibility complex (MHC)-matched GFP+ bone marrow cells harvested from either GALT+ or GALT-null donors. Successful engraftment of GALT+ but not GALT-null cells resulted in > 50% wild-type levels of GALT activity in red blood cells (RBC) and normalized RBC galactose-1-phosphate, a biomarker commonly followed in CG patients. However, GALT activity and galactose metabolites in both liver and brain samples remained essentially unchanged, demonstrating that successful GALT+ BMT in adolescent GALT-null rats was not protective of other tissues.
2025-11-21 | Experimental Galactose-1-Phosphate Uridylyltransferase (GALT) mRNA Therapy Improves Motor-Related Phenotypes in a Mouse Model of Classic Galactosemia—A Pilot Study
Background: Despite life-saving newborn screening programs and a life-long galactose-restricted diet, many patients with classic galactosemia continue to develop long-term debilitating neurological deficits, speech dyspraxia, and primary ovarian insufficiency (POI). In an earlier study, we showed that administration of an experimental human GALT mRNA predominantly expressed in the liver of the GalT gene-trapped mouse model augmented the expression of hepatic GALT activity, which reduced build-up of galactose and its toxic metabolites not only in the liver but also in the peripheral tissues. Moreover, we showed that the administration of GALT mRNA in the mutant mice restored whole-body galactose oxidation (WBGO), which is a functional biomarker. Methods: In this pilot study, we extended our proof-of-concept efficacy studies to a disease-relevant phenotype: motor impairment. GalT-KO mice aged 3 and 6 weeks old administered biweekly intravenous injections of 100 µL GALT mRNA at a dose of 2 mg/kg for 2 months. Motor performance was assessed using rotarod testing and composite phenotype scoring, 3 and 9 weeks following the dosing regimen. Results: Preliminary results showed that a biweekly dosing at 2 mg/kg for 2 months improved the motor performance of the animals in rotarod and composite phenotype scoring tests in a short-term experiment. Conclusions: Despite being a small-scale study, our findings suggest that when treated early in life, the experimental GALT mRNA is effective in improving the motor-related phenotypes in GalT-KO mice using the specified dosing regimen. These findings highlight the potential of mRNA-based therapies for mitigating neurological symptoms in Classic galactosemia.
2025-11-15 | Pretreatment With a Selected Strain of Baker's Yeast, GY007, Prevents the Accumulation of Galactose Metabolites Following Dietary Galactose Exposure in a GALT-Null Rat Model of Classic Galactosemia.
The current standard of care for patients with classic galactosemia (CG) involves lifelong dietary restriction of high galactose foods, including most dairy products. Here, we present the results of a pilot study testing whether pretreatment with GY007, a strain of baker's yeast selected to metabolize galactose despite the presence of other sugars, would be sufficient to prevent the metabolic impact of dietary galactose exposure in a GALT-null rat model of CG. Specifically, we dosed cohorts of adolescent GALT-null rats with either (a) placebo alone, (b) placebo followed by galactose, or (c) GY007 yeast followed by galactose. All rats were treated 3 times daily for 8 consecutive days, for a combined daily dose of almost 27 mg galactose per rat. Wild-type rats dosed with placebo served as controls. All rats also had ad libitum access to water and chow that contained about 0.15% calories from galactose. Rats grew at the expected pace for the duration of the study regardless of treatment group. To test the metabolic efficacy of the GY007 pretreatment, we followed galactose, galactitol, and gal-1P longitudinally in blood, and at euthanasia in brain and liver. In both liver and red blood cells, most metabolites remained near placebo levels despite the galactose exposure, limiting our ability to test the efficacy of GY007 pretreatment in those tissues. However, in both plasma and brain, metabolites showed a significant elevation following galactose exposure, and this rise was prevented by pretreatment with GY007. These results demonstrate the potential of GY007 yeast to prevent the metabolic consequences of transient low-level dietary galactose exposure in GALT deficiency.
2025-10-14 | Myo-Inositol Deficiency, Structural Brain Changes, and Cerebral Perfusion Alterations in Classic Galactosemia: Preliminary Insights From a Multiparametric MRI Study.
Classic galactosemia is a rare metabolic disorder resulting from galactose-1-phosphate uridylyltransferase deficiency, which disrupts normal galactose metabolism, leading to toxic accumulation of galactose-1-phosphate and galactitol. Despite early dietary intervention, patients remain at risk for long-term neurological impairments, including cognitive deficits, motor speech disorders, and psychiatric conditions. The mechanisms driving these persistent abnormalities remain unclear. This study investigated brain metabolic and structural alterations in adults with classic galactosemia using advanced multiparametric MRI. Six patients (3 males, 3 females; mean age 34.0 ± 7.3 years) adhering to lifelong galactose-restricted diets and six age- and sex-matched controls underwent 3T and 7T MRI, including T1-weighted imaging, pseudo-continuous arterial spin labeling, and high-resolution MR spectroscopic imaging. Patients exhibited significantly lower myo-inositol (mIns) concentrations in cerebellum (p = 0.007), putamen (p = 0.023), and cerebral white matter (p = 0.001), reflecting a chronic mIns deficiency despite dietary management. Structural analyses revealed reduced volumes of white matter (p < 0.001), bilateral putamen (p < 0.038), and left thalamus (p = 0.044); alongside increased cortical thickness and reduced cortical surface area, indicating abnormal cortical maturation, particularly in regions associated with motor and cognitive processing. Additionally, cerebral blood flow was elevated in emotion-processing regions, including bilateral amygdala (p < 0.022) and thalamus (p < 0.038). These preliminary findings highlight persistent neurological alterations in classic galactosemia despite dietary management and suggest that chronic mIns deficiency may contribute to the pathophysiology. They underscore the need for larger, longitudinal studies to confirm these results, investigate potential correlations with clinical severity and biochemical markers, and explore therapeutic strategies aimed at modulating mIns metabolism.
2025-10-01 | Exit interviews with caregivers of pediatric patients with classic galactosemia to explore meaningfulness of changes in the ACTION-galactosemia kids trial.
Classic Galactosemia is a rare, autosomal recessive disease in which galactose is not metabolized properly due to severe deficiency/absence of the galactose-1-phosphate uridylyltransferase (GALT) enzyme, converting to an aberrant and toxic metabolite, galactitol. Living with the debilitating symptoms and long-term consequences of Classic Galactosemia creates a heavy burden on patients' and their families' lives. Objectives were to: (1) Evaluate the impact and burden of disease; (2) Qualitatively explore changes in patient symptoms following treatment; and (3) Document the meaningfulness of changes resulting from treatment with govorestat as assessed by the Caregiver Global Impression of Severity (CGIS) and Caregiver Global Impression of Change (CGIC) scales. The AT-007-1002 clinical trial involved a Phase 1/2 dose escalation component (Part A) followed by a Phase 3, randomized, double-blind, placebo-controlled long-term administration component (Part B) that evaluated potential clinical benefit. Exit Interviews were completed prior to unblinding of data. The in-depth, qualitative interviews were semi-structured, using a discussion guide, and conducted by either Zoom or GoToMeeting. Thirty-six caregiver interviews were conducted, capturing the experience of 37 pediatric patients (one caregiver had 2 patients enrolled in the study). Thematic analysis was undertaken to identify themes or patterns within the data. All analyses were conducted on blinded data. Following finalization of the analysis and report findings, post-hoc analysis of the unblinded data was then conducted to explore the meaningfulness of patients experience by treatment arm. This study confirms the substantial burden known to be associated with Classic Galactosemia in a pediatric population. The difficulties experienced were across multiple areas including cognitive function, behavior/social function, motor function, emotional function, communication, vision problems, ovarian insufficiency, sensory difficulties, and sleep problems. The interviews demonstrated that most patients (approximately two thirds) experienced an improvement in symptoms and impacts associated with classic galactosemia over the course of the trial. Nearly all caregivers reported that they perceived a 1-category change on the Caregiver Global Impression of Severity or Caregiver Global Impression of Change items, indicating severity and change respectively, was meaningful to them and the patient. Unblinded analysis of the exit interview data confirmed the patient experience reported by caregivers was different between the treatment arms, providing qualitative support for the treatment benefit of govorestat when compared to placebo. Furthermore, the qualitative data from caregivers provide in-depth insights of their unique lived experience that highlight the substantial impact that this improvement had on the caregiver's and the patient's quality of life. The improvements observed led to a reduction on the burden of Classic Galactosemia and may lead to a greater patient's greater independence. The exit interviews confirmed the burden of Classic Galactosemia disease across multiple domains. Qualitative investigation suggests that observed changes are meaningful to the patient and caregiver, and changes were more commonly reported in those receiving govorestat compared to placebo. Full clinical trial findings will be published separately.
2025-07-14 | A Pilot Study of Bone Marrow Transplantation in a GALT-Null Rat Model of Classic Galactosemia.
Classic galactosemia (CG) is a rare inborn error of metabolism with substantial unmet medical need. Early detection, often by population newborn screening, enables immediate and life-long dietary restriction of galactose, which is the current standard of care. This treatment minimizes or prevents the potentially lethal acute symptoms of disease in infants but fails to prevent the long-term developmental complications experienced by most patients later in childhood. Many possible approaches to improved intervention have been proposed, ranging from small molecule inhibitors or effectors to chaperones to DNA or RNA-based gene therapy, among others. Here, we describe the results of a pilot study testing the potential efficacy of GALT+ bone marrow transplantation (BMT) as a candidate intervention in a GALT-null rat model of CG. Specifically, we pre-treated adolescent GALT-null rats with busulfan for myeloablation and then administered major histocompatibility complex (MHC)-matched GFP+ bone marrow cells harvested from either GALT+ or GALT-null donors. Successful engraftment of GALT+ but not GALT-null cells resulted in > 50% wild-type levels of GALT activity in red blood cells (RBC) and normalized RBC galactose-1-phosphate, a biomarker commonly followed in CG patients. However, GALT activity and galactose metabolites in both liver and brain samples remained essentially unchanged, demonstrating that successful GALT+ BMT in adolescent GALT-null rats was not protective of other tissues.
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Drug Discovery Landscape
1 orphan drug designation for Classic galactosemia.
1 orphan drug designation for Classic galactosemia.
Drug | Therapy type | Regulator | Orphan designation | Approval | Sponsor |
|---|---|---|---|---|---|
Govorestat | small molecules | EMA | 2022-06-21 | — | Advanz Pharma Limited |
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