Are there any emerging treatments beyond dietary restriction, such as enzyme replacement or gene therapy?

Research is ongoing. Small‑molecule chaperones that stabilize residual GALT activity are in early clinical trials, but none are yet approved. Gene‑editing approaches (CRISPR‑based) have shown promise in animal models, yet human trials are still years away. Currently, the standard of care remains strict dietary avoidance of galactose, with supportive therapies for complications.

How strict does the low‑galactose diet need to be, and which foods are considered safe?

ll sources of lactose must be eliminated, because lactose breaks down into glucose + galactose. Safe foods include most fresh meats, fish, eggs, non‑dairy vegetables, fruits (except those with added milk), rice, pasta, and gluten‑free grains. Lactose‑free dairy alternatives (soy, almond, coconut milk) are acceptable if they contain no added galactose. Even trace galactose in processed foods (e.g., certain sauces, baked goods) should be avoided; reading ingredient labels for “lactose,” “milk solids,” or “galactose” is essential.

Even with a strict diet, can classic galactosemia cause long‑term problems, and how are they monitored?

Yes. Despite early dietary control, many patients develop speech delays, learning difficulties, or premature ovarian insufficiency (POI) in females. Annual assessments should include developmental screening, speech‑language evaluation, and, after puberty, measurement of anti‑Müllerian hormone or follicle‑stimulating hormone to gauge ovarian reserve. Liver function tests and cataract exams are also recommended periodically.

What newborn screening tests detect galactosemia, and what steps follow a positive result?

Most states use a heel‑stick dried blood spot to measure GALT enzyme activity or galactose‑1‑phosphate levels. A positive screen prompts a confirmatory quantitative enzyme assay and genetic testing for GALT, GALK1, or GALE mutations. While awaiting results, the infant is placed on a lactose‑free formula (e.g., soy‑based) to prevent acute decompensation. Once the diagnosis is confirmed, lifelong dietary restriction is instituted and a metabolic specialist follows the child.

Galactosemia

Galactosemia is a genetic disorder that impairs the body's ability to process the sugar galactose, causing life‑threatening complications if not treated early. A low‑galactose diet is essential for managing the condition.

Overview

Galactosemia is a disorder that affects how the body processes a simple sugar called galactose. A small amount of galactose is present in many foods, primarily as part of lactose found in dairy products and many baby formulas. The signs and symptoms result from an inability to use galactose to produce energy.

Types

Classic Galactosemia (Type I)

Classic galactosemia is the most common and most severe form. If infants are not treated promptly with a low‑galactose diet, life‑threatening complications appear within a few days after birth. Affected infants typically develop feeding difficulties, lethargy, failure to thrive, jaundice, liver damage, abnormal bleeding, overwhelming bacterial infections, shock, delayed development, cataracts, speech difficulties, intellectual disability, and, in females, premature ovarian insufficiency.

Type II (Galactokinase Deficiency)

Type II causes fewer medical problems than the classic type. Affected infants develop cataracts but otherwise experience few long‑term complications.

Type III (Galactose Epimerase Deficiency)

Type III symptoms vary from mild to severe and can include cataracts, delayed growth and development, intellectual disability, liver disease, and kidney problems.

Symptoms

Feeding difficulties
Lethargy
Failure to thrive
Jaundice
Liver damage
Abnormal bleeding
Overwhelming bacterial infections
Shock
Delayed development
Cataracts
Speech difficulties
Intellectual disability
Premature ovarian insufficiency (in females)

Frequency

Classic galactosemia occurs in 1 in 30,000 to 60,000 newborns. Type II and Type III are less common; type II probably affects fewer than 1 in 100,000 newborns and type III appears to be very rare.

Causes & Risk Factors

Mutations in the GALT, GALK1, and GALE genes cause galactosemia. These genes provide instructions for making enzymes essential for processing galactose obtained from the diet. The enzymes break down galactose into glucose and other molecules the body can store or use for energy.

Mutations in the GALT gene cause classic galactosemia (type I). Most of these genetic changes almost completely eliminate the activity of the enzyme, preventing normal processing of galactose and resulting in life‑threatening signs and symptoms. Another GALT gene mutation, known as the Duarte variant, reduces but does not eliminate enzyme activity, leading to milder features.

Galactosemia type II results from mutations in the GALK1 gene, while mutations in the GALE gene underlie galactosemia type III. A shortage of any of these critical enzymes allows galactose and related compounds to build up to toxic levels, damaging tissues and organs.

Learn more about the genes associated with Galactosemia

GALE
GALK1
GALT

Inheritance

This condition is inherited in an , which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Other Names for This Condition

Classic galactosemia
Epimerase deficiency galactosemia
Galactokinase deficiency disease
Galactose epimerase deficiency
Galactose-1-phosphate uridyl-transferase deficiency disease
GALE deficiency
GALK deficiency
GALT deficiency
UDP-galactose-4-epimerase deficiency disease
UTP hexose-1-phosphate uridylyltransferase deficiency

Resources

Genetic Testing Information

Genetic Testing Registry: Deficiency of galactokinase
Genetic Testing Registry: Deficiency of UDPglucose-hexose-1-phosphate uridylyltransferase
Genetic Testing Registry: Galactosemia
Genetic Testing Registry: UDPglucose-4-epimerase deficiency

Genetic and Rare Diseases Information Center

Galactosemia

Patient Support and Advocacy Resources

National Organization for Rare Disorders (NORD)

Clinical Trials

ClinicalTrials.gov

Catalog of Genes and Diseases from OMIM

GALACTOSEMIA I; GALAC1
GALACTOSEMIA II; GALAC2
GALACTOSEMIA III; GALAC3

Scientific Articles on PubMed

PubMed

MEDICAL ENCYCLOPEDIA

Galactose-1-phospate uridyltransferase
Galactosemia
Genetics

Understanding Genetics

What is the prognosis of a genetic condition?
How can gene variants affect health and development?
What does it mean if a disorder seems to run in my family?
What are the different ways a genetic condition can be inherited?
How are genetic conditions treated or managed?

References

Berry GT. Classic Galactosemia and Clinical Variant Galactosemia. 2000 Feb 4 [updated 2021 Mar 11]. In: Adam MP, Bick S, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews(R) [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2026. Citation on PubMed
Berry GT. Galactosemia: when is it a newborn screening emergency? Mol Genet Metab. 2012 May;106(1):7-11. doi: 10.1016/j.ymgme.2012.03.007. Epub 2012 Mar 21. Citation on PubMed
Bosch AM. Classical galactosaemia revisited. J Inherit Metab Dis. 2006 Aug;29(4):516-25. doi: 10.1007/s10545-006-0382-0. Epub 2006 Jul 11. Citation on PubMed
Fridovich-Keil J, Bean L, He M, Schroer R. Epimerase Deficiency Galactosemia. 2011 Jan 25 [updated 2021 Mar 4]. In: Adam MP, Bick S, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews(R) [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2026. Citation on PubMed
Fridovich-Keil JL, Gambello MJ, Singh RH, Sharer JD. Duarte Galactosemia. 2014 Dec 4 [updated 2025 Dec 4]. In: Adam MP, Bick S, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews(R) [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2026. Citation on PubMed
Fridovich-Keil JL, Gubbels CS, Spencer JB, Sanders RD, Land JA, Rubio-Gozalbo E. Ovarian function in girls and women with GALT-deficiency galactosemia. J Inherit Metab Dis. 2011 Apr;34(2):357-66. doi: 10.1007/s10545-010-9221-4. Epub 2010 Oct 27. Citation on PubMed or Free article on PubMed Central
Karadag N, Zenciroglu A, Eminoglu FT, Dilli D, Karagol BS, Kundak A, Dursun A, Hakan N, Okumus N. Literature review and outcome of classic galactosemia diagnosed in the neonatal period. Clin Lab. 2013;59(9-10):1139-46. doi: 10.7754/clin.lab.2013.121235. Citation on PubMed
Openo KK, Schulz JM, Vargas CA, Orton CS, Epstein MP, Schnur RE, Scaglia F, Berry GT, Gottesman GS, Ficicioglu C, Slonim AE, Schroer RJ, Yu C, Rangel VE, Keenan J, Lamance K, Fridovich-Keil JL. Epimerase-deficiency galactosemia is not a binary condition. Am J Hum Genet. 2006 Jan;78(1):89-102. doi: 10.1086/498985. Epub 2005 Nov 14. Citation on PubMed or Free article on PubMed Central
Timson DJ. The molecular basis of galactosemia - Past, present and future. Gene. 2016 Sep 10;589(2):133-41. doi: 10.1016/j.gene.2015.06.077. Epub 2015 Jul 2. Citation on PubMed