Rare Pediatrics News

Disease Profile

Galactokinase deficiency

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset






Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

GALK deficiency; Galactosemia 2; Hereditary galactokinase deficiency;


Congenital and Genetic Diseases; Digestive Diseases; Endocrine Diseases;


Galactokinase deficiency (GALK), a mild type of galactosemia, is an inherited disorder that impairs the body's ability to process and produce energy from a simple sugar called galactose. If babies with GALK eat foods containing galactose, undigested sugars build up in the blood.[1] Galactose is present in many foods, including all dairy products, many baby formulas, and some fruits and vegetables.[1][2] Children with GALK who are not treated with dietary therapy develop cataracts in the eyes, but otherwise they typically do not have long-term health problems.[2] Rarely, a child with GALK will have pseudotumor cerebri, a condition which mimics the symptoms of a large brain tumor when no brain tumor is present.[3][4] This is thought to be caused by increased pressure in the brain from cerebrospinal fluid (CSF) due to elevated levels of a galactose product in the CSF.[3] The severe medical problems that occur with "classic" galactosemia (type 1), such as liver, kidney, and brain damage, typically are not present in people with GALK.[2][3]

GALK is caused by mutations in the GALK1 gene and inheritance is autosomal recessive.[2] The disorder may be suspected in babies with an abnormal newborn screening result, or in babies with cataracts. The diagnosis can be confirmed with biochemical and molecular genetic testing.[1][3] The treatment is dietary therapy, which involves taking calcium supplements and restricting galactose in the diet throughout life to prevent cataracts.[5] If cataracts develop, they usually resolve with dietary therapy.[1][3] Children with GALK should have their growth monitored, and both children and adults should consult with a dietitian and have regular eye exams.[5]


This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
80%-99% of people have these symptoms
Clouding of the lens of the eye
Cloudy lens

[ more ]

Impairment of galactose metabolism
5%-29% of people have these symptoms
Increased intracranial pressure
Rise in pressure inside skull
Percent of people who have these symptoms is not available through HPO
Autosomal recessive inheritance
Increased urinary galactose level
Prolonged neonatal jaundice
Prolonged yellowing of skin in newborn


Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.

    Newborn Screening

    • An ACTion (ACT) sheet is available for this condition that describes the short-term actions a health professional should follow when an infant has a positive newborn screening result. ACT sheets were developed by experts in collaboration with the American College of Medical Genetics.
    • An Algorithm flowchart is available for this condition for determining the final diagnosis in an infant with a positive newborn screening result. Algorithms are developed by experts in collaboration with the American College of Medical Genetics.
    • Baby's First Test is the nation's newborn screening education center for families and providers. This site provides information and resources about screening at the local, state, and national levels and serves as the Clearinghouse for newborn screening information.
    • The Newborn Screening Coding and Terminology Guide has information on the standard codes used for newborn screening tests. Using these standards helps compare data across different laboratories. This resource was created by the National Library of Medicine.
    • National Newborn Screening and Global Resource Center (NNSGRC) provides information and resources in the area of newborn screening and genetics to benefit health professionals, the public health community, consumers and government officials.


      Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

      Organizations Supporting this Disease

        Learn more

        These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

        Where to Start

        • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
        • Genetics Home Reference (GHR) contains information on Galactokinase deficiency. This website is maintained by the National Library of Medicine.

          In-Depth Information

          • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
          • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
          • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
          • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
          • PubMed is a searchable database of medical literature and lists journal articles that discuss Galactokinase deficiency. Click on the link to view a sample search on this topic.


            1. Galactokinase deficiency. Baby's First Test. https://www.babysfirsttest.org/newborn-screening/conditions/galactokinase-deficiency. Accessed 10/9/2018.
            2. Galactosemia. Genetics Home Reference. August, 2015; https://www.ghr.nlm.nih.gov/condition=galactosemia.
            3. Sutton VR. Galactosemia: Clinical features and diagnosis. UpToDate. Waltham, MA: UpToDate; July 18, 2018; https://www.uptodate.com/contents/galactosemia-clinical-features-and-diagnosis.
            4. Pseudotumor Cerebri Information Page. National Institute of Neurological Disorders and Stroke (NINDS). June 20, 2018; https://www.ninds.nih.gov/Disorders/All-Disorders/Pseudotumor-Cerebri-Information-Page.
            5. Sutton VR. Galactosemia: Management and outcome. UpToDate. Waltham, MA: UpToDate; March 13, 2017; https://www.uptodate.com/contents/galactosemia-management-and-outcome.