Galactosaemia is a group of genetic, metabolic conditions where the body is unable to break down (process) a type of sugar called galactose.^1,2 Galactose is found in many types of food, particularly dairy products. The body usually breaks down galactose to produce energy. In individuals with galactosaemia, the galactose is not processed and it builds up (accumulates) in the blood. This build up can become toxic, resulting in a range of symptoms and in some cases, can be life-threatening.

Galactosaemia is caused by genetic changes in genes that are involved in the break down of galactose (galactose metabolism). Depending on the gene that is affected, this would result in different type of galactosaemia. The different types of galactosaemia differ in their range of symptoms and severity:¹

• Classic galactosaemia (type 1; GALT) – a severe, life-threatening form in individuals with no or low GALT enzyme activity [please note that there are other GALT variants/conditions where there is higher GALT enzyme activity which may result in milder or no symptoms – these are not classified as classic galactosaemia, and are not covered fully on this page]
• Galactokinase deficiency (type 2; GALK) – a mild form that mainly causes cataracts
• Galactose epimerase deficiency (type 3; GALE) – ranges from mild/moderate (when only some cells or tissues are affected) to severe and life-threatening (severely affecting overall body systems)
• Galactose mutarotase deficiency (type 4; GALM) – a relatively mild form but which is not as well understood than the other types

In Australia, galactosaemia is often detected shortly after birth via newborn bloodspot screening (NBS) programs. Additional testing is required to confirm a diagnosis and determine the type of galactosaemia. For individuals who are not screened at birth, galactosaemia is often diagnosed after symptoms develop. Management of galactosaemia involves a life-long galactose-restricted diet where individuals have to avoid or restrict foods containing lactose, milk and other sources of galactose.^3,4 Early detection and management of galactosaemia is important to prevent or reduce serious complications, including life-threatening complications.

Synonyms:  galactose intolerance; galactosemia

Universal rare disease classifications provide a common language for recording, reporting and monitoring diseases. Please visit the Rare Disease Classifications page for more information about these internationally recognised classifications.

ORPHA:352 Galactosemia

• ORPHA:79239 Classic galactosemia
• ORPHA:79237 Galactokinase deficiency
• ORPHA:79238 Galactose epimerase deficiency
• ORPHA:570422 Galactose mutarotase deficiency

ICD11: 5C51.4 Disorders of galactose metabolism

•  5C51.40 Galactose-1-phosphate uridyltransferase deficiency
•  5C51.41 Galactokinase deficiency
•  5C51.4Y Other specified disorders of galactose metabolism

Symptoms of galactosaemia vary between the different types. If left untreated, symptoms that can develop for the different types may include:

Classic galactosaemia (type 1; GALT)^5-8

Symptoms associated with no or low GALT enzyme activity may include feeding issues, failure to thrive (do not gain weight and grow as expected), lethargy (lack of energy), jaundice (yellowing of skin and eyes), liver damage and bleeding in babies, and can quickly lead to life-threatening complications such as liver failure, sepsis and early death. Even with treatment, children may have developmental delays, with speech issues and issues with their motor function, poor growth, intellectual disability, cataracts, and females can go on to have ovarian issues.

Please note that individuals with a higher GALT enzyme activity may have clinical variant galactosaemia or Duarte galactosaemia, which is different from classic galactosaemia. Those with clinical variant galactosaemia may have milder symptoms but the symptoms can still be life-threatening; however, individuals are less likely to have long term complications. Individuals with Duarte galactosaemia typically do not display any symptoms (asymptomatic). Information on this page is focussed on classic galactosaemia and not these other variants.

Galactokinase deficiency (type 2; GALK)^9-11

Children often develop cataracts during the first weeks or months of life due to build-up of galactitol (a product of galactose) in the lens of the eyes, but do not have the severe symptoms seen in type 1. There may be other symptoms, such as pseudotumor cerebri. Pseudotumor cerebri, also known as idiopathic intracranial hypertension, is caused by increased cerebrospinal fluid pressure in the brain and results in symptoms similar to those caused by a brain tumour.

Galactose epimerase deficiency (type 3; GALE)^12-14

Symptoms vary widely between individuals depending on the different forms of galactose epimerase deficiency, based on which tissues are affected and have no or lower GALE activity. Individuals with the generalised form generally have very low or no enzyme activity in all tissues, and have symptoms similar to the classic galactosaemia. Those with the peripheral form (mainly circulating red and white blood cells affected) typically do not have any symptoms whilst the intermediate form (circulating red and blood cells affected with other tissues having slightly lower activity) may have no or short-term illness during the newborn stage.

Galactose mutarotase deficiency (type 4; GALM)^15-17

As this galactosaemia type was only identified in 2019, it is not as well understood as the other types. It has been reported to be a milder form compared to the other types, and symptoms include mild cataracts and mild liver impairment.

Please speak to your medical team to learn more about the symptoms and complications of a specific type of galactosaemia.

Rare diseases are often serious and progressive, exhibiting a high degree of symptom complexity, leading to significant disability. Majority of the estimated two million Australians living with a rare disease meet the Australian Government’s definition for disability (in accordance to the Australian Public Service Commission and Australian Bureau of Statistics), and many experience severe and permanent disability impacts. If you or someone you care for is experiencing disability-related impacts from a rare condition, please speak with a health or disability professional for advice. Information about relevant disability support can be found at the RARE Portal’s Disability Support Information page.

Orphanet: Disability – Classic galactosemia has information about the functional impacts that people with classic galactosemia may experience; please note that this was last updated in 2015 and may not reflect the most current information.

Orphanet: Disability – Galactokinase deficiency has information about the functional impacts that people with galactokinase deficiency may experience; please note that this was last updated in 2023 and may not reflect the most current information.

Orphanet: Disability – Galactose epimerase deficiency does not provide information about the functional impacts for galactose epimerase deficiency due to the extreme variability of its presentation reported between individuals.

Orphanet has not have information about functional impacts for galactose mutarotase deficiency.

Galactosaemia are genetic conditions. It is caused by disease-causing genetic changes (variants) in the genes that are involved in the body’s process of breaking down galactose, a sugar that is found in many types of food, especially in dairy.^1,2

Different genes (responsible for producing different enzymes) are affected in the different types of galactosaemia:

• Classic galactosaemia – GALT gene (galactose-1-phosphate uridyltransferase enzyme)
• Galactokinase deficiency – GALK1 gene (galactokinase enzyme)
• Galactose epimerase deficiency – GALE gene (UDP-galactose-4-epimerase enzyme)
• Galactose mutarotase deficiency  – GALM gene (galactose mutarotase enzyme)

All individuals have two copies (alleles) of each gene – one on each chromosome that is inherited from each parent. Galactosaemia are autosomal recessive conditions, which means both copies of the affected gene must have the disease-causing genetic variants. More information on autosomal recessive inheritance pattern can be found at Centre for Genetics Education: Autosomal recessive inheritance.

If you would like to learn more about the inheritance and impact of this condition, please ask your doctor for a referral to a genetic counsellor. Genetic counsellors are qualified allied health professionals who can provide information and support regarding genetic conditions and testing. More information about genetic counselling can be found at:

• Information on Genetic Services
• The National and State Services pages underneath the ‘Genetic Counselling’ sections listed

Newborn screening

In Australia, galactosaemia is usually detected via the newborn bloodspot screening (NBS) programs.  Shortly after birth and with parental consent, a nurse or midwife will collect the baby’s blood via a heel prick blood test. The healthcare provider will then send it to a specific laboratory to test for a range of rare conditions, including galactosaemia. If the test results suggest that there is a risk of the baby having one of screened conditions, laboratory staff will promptly get in touch with healthcare providers. The healthcare providers will then arrange for the baby to have further testing to confirm if the baby actually has the condition. The healthcare providers will also organise for the baby to receive urgent care if required. Depending on your state or territory, parents may or may not receive a notification if the test results are clear. You can find out more about NBS in your state or territory at Australian Government Department of Health, Disability and Ageing: Delivering newborn bloodspot screening programs.

Newborn bloodspot screening is a reliable way to check for certain rare conditions early in life. Although it’s extremely rare, cases can sometimes be missed. If you are concerned your baby may have a condition that they have already been screened for, you should contact a medical professional.

Diagnosis

A diagnosis of galactosaemia may be suspected based on an abnormal result from NBS but additional tests will be required to confirm a diagnosis and determine the type of galactosaemia. For individuals who are not screened at birth, galactosaemia is often diagnosed after symptoms develop.

Diagnosis of galactosaemia may be made based on:¹

• clinical examination
• biochemical tests on blood samples to detect increased levels of galactose and galactose-1-phosphate levels; tests may also be done on urine samples to detect for some forms of galactose
• enzyme assays to measure activity of the different enzymes involved in galactose breakdown
• genetic testing to look for genetic changes in the GALT, GALK1, GALE or GALM gene.

Please speak to your medical team to learn more about the available pathways for diagnosis of this condition.

There is no curative treatment for galactosaemia. Management of galactosaemia involves a life-long galactose-restricted diet where individuals have to avoid or restrict foods containing lactose, milk and other sources of galactose, along with regular follow-ups, as well as monitoring for and management of symptoms.^3,4 The Galactosaemia Handbook prepared by the Australasian Society for Inborn Errors of Metabolism (ASIEM) has further information about the galactose-restricted diet. Early detection and management of galactosaemia can help prevent or reduce serious complications, including life-threatening complications. There may be some symptoms that may not be prevented or managed fully by the galactose-restricted diet (even with early and adequate treatment), and may need to be monitored for, and further managed. Management of symptoms may include speech therapy, occupational therapy, physiotherapy, as well as management of cataracts, bone health and ovarian issues, such as hypergonadotropic hypogonadism and primary ovarian insufficiency.

Please speak to your medical team to learn more about the possible treatment or management options for your condition. Treatment will depend on an individual’s specific condition and symptoms. It is also important to stay connected to your medical team so that you can be made aware of any upcoming clinical trial opportunities. For many rare diseases, treatment options may be limited. Participation in a clinical trial may provide access to new or emerging therapies.

Healthcare professionals involved in the clinical care of individuals of galactosaemia may include metabolic doctors, nurses, geneticists, dieticians, speech pathologists, and healthcare workers who are trained to look after people with metabolic disorders. The need for different healthcare professionals may change over a person’s lifetime and extend beyond those listed here.

Clinical care for rare diseases often involves a multidisciplinary team of medical, care and support professionals. Please note that the information provided here is as a guide and that RVA does not necessarily monitor or endorse specific clinics or health experts.

This may not be applicable to all rare diseases but for many, palliative care services may be relevant and useful. Palliative care services are available for people (adults, children and their families) living with a life-limiting illness and is not only for end-of-life care. It can also help at any stage of illness from diagnosis onwards, and will look different for different people. Palliative care services provide assistance, support, resources and tools to help people manage their illness and the symptoms, ease pain, and improve comfort and quality of life. If this is relevant to you and you wish to find out more information about palliative care and how it can help you, please visit:

• Australian Institute of Health and Welfare: Palliative care Overview
• Australian Government Department of Health, Disability and Ageing: Palliative care
• Palliative Care Australia

The Galactosaemia Handbook was prepared by a working party of the Australasian Society for Inborn Errors of Metabolism, a special interest group of the Human Genetic Society of Australasia; published in 2024.

The International clinical guideline for the management of classical galactosemia: diagnosis, treatment, and follow-up was developed by members of The Galactosemia Network (GalNet); published in 2017.

Individuals living with rare diseases may have complex medical issues and disabilities, which are not always visible. It is often useful to refer to their medical history as well as personal information such as a medical card, doctor’s letter, or if available, a rare disease passport, for relevant information.

In addition, individuals, their parents, families and carers often develop extensive expertise on their specific rare disease. It is important to recognise that they can contribute valuable knowledge about their rare condition. Rare diseases often impact individuals differently, so it’s important to consider a person’s lived experience.

If you know of any relevant emergency management guidelines or information relevant to emergency care, please let us know via the  Contribute page.

The Galactosemia Network (GalNet) is the international network for galactosemia established in 2012. It includes professionals from Austria, Belgium, Bulgaria, Croatia, Czech Republic, Estonia, France, Georgia, Germany, Greece, Ireland, Italy, Lithuania, Netherlands, Poland, Portugal, Spain, Switzerland, the United Kingdom, Turkey, the United States of America, Australia and several South American countries. It is open for clinicians and researchers from all countries in order to improve the care of patients worldwide. The GalNet focuses on the advancement of research, diagnosis, treatment and follow-up care of galactosemic patients by close collaboration among the various stakeholders, clinicians, researchers, nutritionists, and patients and families.

There are specific considerations around participating in rare disease research, including clinical trials. It is important to be mindful of issues such as data privacy, research ethics, consent and differences in research regulations between Australia and other countries. For more information, please visit the RARE Portal’s Considerations for Participating in Health and Medical Research page.

If you are interested in finding clinical trials for your condition, please visit the following websites; however, there may not be any clinical trials available:

• Australian Clinical Trials
• ClinicalTrials.gov

It is best to discuss your interest in research, including clinical trials,  with your medical team to determine suitability and eligibility.

Australian Organisation:

Australian Galactosaemia Support Network
Website: https://agsn.org.au/

The Australian Galactosaemia Support Network provides vital support, resources, and advocacy for families living with galactosaemia. They work to improve understanding of this rare genetic condition and ensure families have access to the information and support they need.

Please note that RVA does not monitor or endorse each group/organisation’s operational governance and activities. When engaging with a group, please consider the information on the RARE Portal’s Finding Helpful Peer and Community Supports page.

Galactosaemia varies between individuals, and each person’s experience is unique.

If you would like to share your personal story with RVA, please visit the Rare Voices Australia: Share Your Story page. RVA will consider your story for publishing on our website and inclusion on the RARE Portal.

For information on available government and social services that provide support for individuals with a rare disease, please visit the National and State Services pages.

People living with a rare disease often face unique challenges such as diagnostic delays, misdiagnoses, limited treatment options, and limited access to rare disease specialists and support. These challenges may impact people’s emotional wellbeing and quality of life. Many find it helpful to seek mental health and wellbeing support to cope with ongoing stress and uncertainty. Connecting with people who have shared experiences through a support group may also be helpful. Information about relevant mental health and wellbeing support can be found at:

• Mental Health and Wellbeing Support for Australians Living with a Rare Disease
• The National and State Services pages underneath the ‘Mental Health’ sections listed

Further information on galactosaemia can be found at:

• • The Galactosaemia Handbook prepared by the Australasian Society for Inborn Errors of Metabolism (ASIEM)
  • Genetic and Rare Diseases (GARD) Information Center: Galactosaemia
  • Genetic and Rare Diseases (GARD) Information Center: Classic galactosemia
  • Genetic and Rare Diseases (GARD) Information Center: Galactokinase deficiency
  • Genetic and Rare Diseases (GARD) Information Center: Galactose epimerase deficiency
  • Genetic and Rare Diseases (GARD) Information Center: Galactosemia 4

Royal College of Pathologists of Australasia (RCPA): Galactosaemia

GeneReviews^®:Classic Galactosemia and Clinical Variant Galactosemia

GeneReviews^®: Epimerase Deficiency Galactosemia

Online Mendelian Inheritance in Man, OMIM^® : #230400 Galactosemia I; GALAC1

Online Mendelian Inheritance in Man, OMIM^® :#230200 Galactosemia II; GALAC2

Online Mendelian Inheritance in Man, OMIM^® :#230350 Galactosemia III; GALAC3 

Online Mendelian Inheritance in Man, OMIM^® :#618881. Galactosemia IV; GALAC4

This page has been developed by Rare Voices Australia (RVA)’s RARE Portal team. If you would like to see more information added to this page, please reach out via the Contact form. If you would like to share relevant resources for this condition, please visit the Contribute page.

If you are aware of any additional information that may benefit stakeholders with an interest in this page, or if you notice any broken links or inaccurate information, please let us know via the Contribute page.