Galactose Degradation Pathway
Galactose Pathway
Galactosemia is an inherited metabolic disorder that can lead to life-threatening complications unless a lactose-restricted diet is immediately provided after birth. During normal digestion, the enzyme lactase breaks lactose (primarily found in dairy products, including baby formula) into galactose and glucose. Individuals with galactosemia lack, or are missing, specific enzymes needed for further breakdown of galactose into uridine diphosphate (UDP)-glucose and, ultimately, carbon dioxide.

Three types of galactosemia can occur:
Enzyme Deficiency Differentiating Characteristics
uridyl-transferase (GALT)
Results in classic galactosemia, in which homozygotes have less than 5% enzyme activity. If untreated, severe damage of body systems can occur; if undetected, death.

Children with Duarte variant galactosemia generally have a residual 10-25% GALT enzyme activity. It occurs when a child inherits a classic mutation from one parent and the Duarte variant from the other. It is similar to Classic galactosemia, but less severe. Depending on severity, no treatment may be needed.
Galactokinase 1 (GALK1) Results in relatively mild symptoms, although may cause cataracts. Individuals still have normal GALT enzyme activity.
UDP-galactose-4-epimerase (GALE) Either results in deficiency that is found only in red blood cells and no symptoms occur, or a deficiency that affects most tissues and results in symptoms similar to those found in classic galactosemia.

GALT deficiency causes the most common and severe form of galactosemia and will be the focus of the following discussion.

Other Names & Coding

Classic galactosemia (galactosemia type I, GALT deficiency, galactose-1-phosphate uridyltransferase deficiency)
Duarte galactosemia (mild galactosemia)
Galactokinase deficiency disease (GALK deficiency, galactosemia type II)
UDP-galactose-4-epimerase deficiency disease (GALE deficiency, galactosemia III)
ICD-10 coding

E74.21, galactosemia

Further coding details can be found at ICD-10 for Galactosemia (


GALT deficiency occurs approximately 1 in 30,000 individuals. [Bosch: 2005] The Duarte variant occurs in about 1 in 16,000.

GALK deficiency seems to be rare; although there have been no large population studies, the estimated prevalence is less than 1 in 100,000. [Elsas: 2010]

GALE deficiency occurs in two forms. One form is confined to red blood cells and has no symptoms and the second form, which is exceedingly rare, involves most body systems; only a few patients have been reported nationally. [Holton: 2001] [Openo: 2006]


Galactosemia is inherited in an autosomal recessive manner. More than 200 known genetic mutations cause classic galactosemia or variants, such as the Duarte variant. [McCorvie: 2011]


With treatment, most clinical complications can be prevented and a normal life expectancy achieved; however, intellectual disability, speech problems, reduced coordination, and primary amenorrhea or premature menopause can occur despite adherence to galactose-restricted diets. [Hoffmann: 2012] [Bosch: 2009]

Practice Guidelines

There are no published guidelines for the diagnosis or management of children with galactosemia.

Roles of the Medical Home

In addition to providing primary care, the medical home works collaboratively with families to reinforce successful dietary strategies at home and in the classroom. Families often need substantial support in understanding and implementing the dietary restrictions, which work best when the entire family participates, and managing the unavoidable effects of the condition. Parents likely will benefit from accessing family-supported and community-based organizations.

Clinical Assessment

Pearls & Alerts for Assessment

Sepsis in newborns may signal galactosemia

Escherichia Coli is the most common bacteria causing sepsis in infants with galactosemia, but Klebsiella, Enterobacter, Staphylococcus, group-B strep, and Streptococcus faecalis also have been observed.

Osteoporosis common in children with galactosemia

Calcium supplementation at 750 mg/day in neonates and >1200 mg/day in children, along with vitamin D3 (cholecalciferol) at 1000 IU/day, may prevent decreased bone mineralization. It is not clear how to prevent chronic secondary effects such as hypergonadotropic hypogonadism in females, ataxia, and growth delays. [Elsas: 2010]

High false positive newborn screen results

Most children who have a positive screening test will have neither classic galactosemia nor Duarte variant. The newborn with questionable screening results should be treated with soy-based formula pending definitive results from further tests.


For the Condition

Virtually 100% of affected infants can be detected in state newborn screening programs that test for galactosemia by measuring GALT activity. [Elsas: 2010] Some centers also measure galactose levels that become elevated in GALK and GALE deficient galactosemia. Enzyme isoelectric focusing can be helpful in cases of intermediate enzyme activity levels, where ranges for Duarte galactosemia and other carrier states may overlap. Prenatal diagnosis is possible for pregnancies at 25% risk for classic galactosemia using molecular genetic testing if the disease-causing GALT mutations in the family are known. [Elsas: 2010] The Medical Home Portal's Newborn Disorder page on Galactosemia contains more detailed information.

Of Family Members

Couples who have had one affected child have a 25% chance of having an affected child in each subsequent pregnancy. [Elsas: 2010] Subsequent siblings of children with galactosemia should be screened either prenatally or at birth (GALT enzyme activity and genetic testing). Lactose containing substances, including breast milk, should not be given until results are available. [Elsas: 2010]

For Complications

Because of their relative frequency in individuals with galactosemia, screening for the following are indicated:
  • Delays in speech and language development
  • Delays in cognitive or learning development
  • Cataracts (though they may have little impact on vision) [Widger: 2010]
  • Sudden increases in toxic analytes – RBC gal-1-P and urinary galactitol, generally monitored through periodic visits with metabolic genetics
  • Primary ovarian insufficiency/failure in girls


Newborns with classic galactosemia are usually symptom-free for the first few days or week of life, until ingestion of breast milk or lactose-containing formula results in: [Waggoner: 1990]
  • Jaundice
  • Vomiting
  • Hepatomegaly
  • Failure to thrive
  • Poor feeding
  • Lethargy and Irritability
  • Diarrhea
  • Sepsis (usually Escherichia coli sepsis)
Presentations of long-term problems, even when treatment is initiated before the acute event, may include: [Michael: 2014]
  • Poor growth
  • Learning disabilities
  • Speech apraxia
  • Unsteady gait
  • Fine and gross motor skill delays
  • Cataracts, which usually regress with dietary treatment and leave no remaining visual impairment
  • Decreased bone mineral density
  • Ataxia and tremor

Ataxia and tremor may become evident with time in some patients. Some mutations, such as Q188R or K285N, are more likely to be associated with severe outcome. Mild GALT may show similar, but less severe, symptoms than classic galactosemia.

Children deficient in GALK may have increased blood galactose and cataracts but no other problems.

GALE deficiency may present with liver disease and a high galactose-1-phosphate level, but normal GALT activity. There are two variants of this condition: one restricted to the red cells that is usually benign, and one where the liver is affected, causing the same symptoms of classic galactosemia.

Clinical Classification

In classic (G/G) galactosemia, GALT enzyme activity is less than 5% of control values and erythrocyte gal-1-P is higher than 10 mg/dL. In Duarte variant (D/G) galactosemia, GALT enzyme activity is usually higher than 5% and often approximates 25% of control values.

Differential Diagnosis

Any condition that causes liver damage in neonates may be confused with galactosemia including:

History & Examination

Current & Past Medical History

Children usually present at 5-14 days of age. Many have history of hyperbilirubinemia.

Family History

Because this is an autosomal recessive condition, there is often no family history.

Developmental & Educational Progress

Delays in development, if any, are not usually very severe, unless there is brain damage from the initial event. Ongoing surveillance of development and periodic assessment of school performance may help identify delays/problems early. The impact of specific interventions is not known.

Maturational Progress

Premature ovarian insufficiency is present in a majority of girls with galactosemia and may present as primary or secondary amenorrhea. [Elsas: 2010]

Physical Exam

Growth Parameters

Growth may be delayed during childhood.


Girls with abnormal estrogen levels due to premature ovarian insufficiency may present with cutaneous rashes.


Although rarely needing treatment, cataracts may be visible.

Neurologic Exam

Delayed acquisition of motor skills, poor coordination, and ataxia may be noted.


Genetic Testing

Enzyme assay in red blood cells and gene testing in consultation with metabolic genetics is necessary to distinguish among galactosemia types. [Berry: 2012]

Specialty Collaborations & Other Services

Pediatric Metabolics (see RI providers [2])

Provides diagnostic confirmation, management of dietary treatment, and monitoring for complications.

Nutrition, Metabolic (see RI providers [18])

Provides expertise in initiation and management of dietary restrictions and will work with the family to address dietary challenges.

Treatment & Management


Children with classic galactosemia are treated with a lactose-restricted diet. Despite therapy, affected individuals can have life-long problems. These problems are thought to be due to endogenous production of galactose and the accumulation of galactose-1-phosphate. Patients with Duarte variant galactosemia usually do not need lactose restriction and are not at risk for sepsis.

Pearls & Alerts for Treatment & Management

Complications despite dietary restriction

Despite even rigorous galactose avoidance, individuals may still have symptoms, including mild to moderate intellectual disability, growth problems, speech and language problems, and ataxia.

Hidden lactose in foods

Lactose may be found in whey, milk solids, and dry milk powder, as well as in some non-milk products like fermented soy, legumes, tomato sauces, and organ meats.

Hidden lactose in medication

Certain medications have galactose or lactose fillers. These are not required to be listed in supplements. Avoid casein hydrolysates (Alimentum®, Nutramigen®, Pregestimil®) and medications with lactulose. [Elsas: 2010]

Fruit and vegetable galactose controversy

Free galactose is present in some fruits and vegetables, such as tomatoes, brussel sprouts, bananas, and apples. There is no consensus about whether these should be eliminated from the diet because endogenous synthesis of galactose also occurs. Some have suggested that an elemental formula (galactose free) may be preferable to soy formula in the treatment of galactosemia. [Gropper: 2000] [Segal: 1998] [Zlatunich: 2005]



Upon presentation, infants will be referred to metabolic genetics. The child will need frequent follow-up in the first couple of years. Adherence to the diet should be life-long, but can be relaxed a little after puberty. Genetic counseling will usually be provided to support decision-making regarding future children.

Specialty Collaborations & Other Services

Pediatric Metabolics (see RI providers [2])

Co-management should be established with metabolic genetics.

Nutrition, Metabolic (see RI providers [18])

Initiates and adjusts a lactose-free diet.

Genetic Testing and Counseling (see RI providers [8])

Helps families understand the inheritance pattern and risks for subsequent children.

Development (general)

Despite optimal adherence to a lactose-free diet, measurable levels of galactose will persist, most likely due to endogenous galactose production. Currently, there is no way to prevent this, although studies are in progress. The primary care clinician should monitor children for developmental delays/intellectual disability, order appropriate therapies when needed, and evaluate periodically for coordination problems or problems with balance.

Specialty Collaborations & Other Services

Early Intervention for Children with Disabilities/Delays (see RI providers [13])

All children who test positive for classic galactosemia should be referred for early intervention evaluation and, if indicated, treatment.

Developmental - Behavioral Pediatrics (see RI providers [11])

An evaluation by developmental pediatrics may be helpful for children who are behind developmentally or who have attention or learning problems.

Physical Therapy (see RI providers [3])

May be helpful for patients with gross motor developmental delays and/or coordination problems/ataxia.

Occupational Therapy (see RI providers [10])

May be helpful for patients with fine motor delays or problems with activities of daily living.

Speech - Language Pathologists (see RI providers [23])

May be helpful for patients with language delay or articulation problems.

Pediatric Physical Medicine & Rehabilitation (see RI providers [3])

Depending on local expertise and availability, may help with physical evaluation and management plan.


Cataracts are seen in approximately 30% of children with galactosemia. [Elsas: 2010] Although they may not cause serious visual problems, children should be monitored yearly.

Specialty Collaborations & Other Services

Pediatric Ophthalmology (see RI providers [8])

Periodic visits with pediatric ophthalmology are necessary to monitor for cataracts and treat as needed.


Primary ovarian insufficiency/failure is common in girls with galactosemia. This can lead to failure to develop secondary sexual characters, infertility, and early menopause (in some cases by age 20). Anti-Mullerian hormone, follicle stimulating hormone, luteinizing hormone, and estradiol should be measured in pre-teen girls; referral to an endocrinologist should be offered when hormone treatment is indicated.

Specialty Collaborations & Other Services

Pediatric Endocrinology (see RI providers [13])

Assists in evaluation and management of girls with ovarian insufficiency.

Issues Related to Galactosemia

No Related Issues were found for this diagnosis.

Ask the Specialist

My daughter was diagnosed with galactosemia when she was 2 days old, since then we have always avoided galactose. Despite this, she struggles in school and with her speech. Why is she not doing better?

Individuals with galactosemia are often developmentally delayed, even when families have strictly adhered to a galactose free diet. Some children may receive galactose in foods that are not expected to contain galactose, or their bodies produce galactose as part of their normal metabolism. Either situation may contribute to higher than normal galactose levels and subsequent problems. The Lactose-Free Diet Guidelines (Sutter Health) may be helpful for answering questions about food inclusions.

Resources for Clinicians

On the Web

The Medical Home Portal's newborn disorders page for galactosemia provides information about the newborn screening process, follow-up on positive screening results, and steps to be taken after diagnosis confirmation.

Galactosemia (GeneReviews)
Detailed information addressing clinical characteristics, diagnosis/testing, management, genetic counseling, and molecular pathogenesis; from the University of Washington and the National Library of Medicine.

Galactosemia (GARD)
Includes information about symptoms, inheritance, diagnosis, finding a specialist, related diseases, and support organizations; Genetic and Rare Diseases Information Center of the National Center for Advancing Translational Sciences.

Classic Galactosemia (Orphanet)
Overview of galactosemia and links to more information, services, and other resources; from Orphanet, a French-coordinated consortium involving over 40 countries to provide a portal for information about rare diseases and orphan drugs.

ACT Sheet for Classic Galactosemia (ACMG) (PDF Document 348 KB)
Contains short-term recommendations for clinical follow-up of the newborn who has screened positive; American College of Medical Genetics.

ACT Sheet for Primary or Secondary Hypergalactosemia (ACMG) (PDF Document 345 KB)
Contains short-term recommendations for clinical follow-up of the newborn who has screened positive; American College of Medical Genetics.

Helpful Articles

PubMed search for galactosemia and neonatal screening, last 5 years.

Bosch AM.
Classical galactosaemia revisited.
J Inherit Metab Dis. 2006;29(4):516-25. PubMed abstract / Full Text
Review of classic galactosemia from the University Hospital of Amsterdam.

Elsas LJ.
GeneReview. 2010. PubMed abstract / Full Text
Includes disease characteristics and genetic, diagnosis, and management information.

Walter, JH, Collins, JE, Leonard, JV.
Recommendations for the management of galactosemia.
Arch Dis Child. 1999;80:93-96. PubMed abstract / Full Text
Recommendations for the evaluation and management of galactosemia. Despite being written in 1999, still contains pertinent information; from the UK Galactosemia Screening Group.

Resources for Patients & Families

Information on the Web

Galactosemia (MedlinePlus)
Information for families that includes description, frequency, causes, inheritance, other names, and additional resources; from the National Library of Medicine.

Galactosemia Tutorial for Parents (English and Spanish)
Tutorials on congenital conditions; Patient Education Institute, Iowa Department of Health's Center for Congenital and Inherited Disorders.

Resources for Galactosemia (Disease InfoSearch)
Compilation of information, articles, research, case studies, and genetics links; from Genetic Alliance.

Lactose-Free Diet Guidelines (Sutter Health)
A comprehensive guide to dietary restrictions needed to avoid lactose.

National & Local Support

Galactosemia Foundation
Provides information about galactosemia and facilitates networking among families, clinicians, and researchers.


Studies of Galactosemia (
Studies looking at better understanding, diagnosing, and treating this condition; from the National Library of Medicine.

Services for Patients & Families in Rhode Island (RI)

For services not listed above, browse our Services categories or search our database.

* number of provider listings may vary by how states categorize services, whether providers are listed by organization or individual, how services are organized in the state, and other factors; Nationwide (NW) providers are generally limited to web-based services, provider locator services, and organizations that serve children from across the nation.

Authors & Reviewers

Initial publication: April 2014
Current Authors and Reviewers:
Author: Nicola Longo, MD, Ph.D.


Berry GT.
Galactosemia: when is it a newborn screening emergency?.
Mol Genet Metab. 2012;106(1):7-11. PubMed abstract
An excellent review regarding response to, and family counseling for, children who have a positive newborn screening result for galactosemia.

Bosch AM.
Classical galactosaemia revisited.
J Inherit Metab Dis. 2006;29(4):516-25. PubMed abstract / Full Text
Review of classic galactosemia from the University Hospital of Amsterdam.

Bosch AM, Ijlst L, Oostheim W, Mulders J, Bakker HD, Wijburg FA, Wanders RJ, Waterham HR.
Identification of novel mutations in classical galactosemia.
Hum Mutat. 2005;25(5):502. PubMed abstract / Full Text
Report of the mutational spectrum of classical galactosemia in a cohort of 123 Dutch patients, all with biochemically proven classical galactosemia.

Bosch AM, Maurice-Stam H, Wijburg FA, Grootenhuis MA.
Remarkable differences: the course of life of young adults with galactosaemia and PKU.
J Inherit Metab Dis. 2009;32(6):706-12. PubMed abstract
Investigates the course of life and the social demographical outcomes in young adults with galactosaemia and compares them with the general population and with PKU patients.

Elsas LJ.
GeneReview. 2010. PubMed abstract / Full Text
Includes disease characteristics and genetic, diagnosis, and management information.

Gerard T Berry, MD; Chief Editor: Bruce Buehler, MD.
Galactose-1-phosphate uridyltransferase deficiency (galactosemia) differential diagnoses.
Medscape; (2014) Accessed on 2/17/2014.
Diagnosis and treatment information for galactosemia.

Gropper S.
Free Galactose Content of Fresh Fruits and Strained Fruit and Vegetable Baby Foods: More Foods to Consider for the Galactose-restricted Diet.
Journal of the American Dietetic Association. 2000;100(5). PubMed abstract
Examines free galactose content of foods and discusses restriction issues.

Hoffmann B, Dragano N, Schweitzer-Krantz S.
Living situation, occupation and health-related quality of life in adult patients with classic galactosemia.
J Inherit Metab Dis. 2012. PubMed abstract
Evaluates psychosocial, educational, and occupational outcome as well as health-related quality of life in adult German patients with galactosemia. Compares information with data from patients with phenylketonuria as well as the general German population.

Holton JB, Walter JH, Tyfield LA. .
The Metabolic and Molecular Bases of Inherited Disease.
8th ed. ed. New York, NY: McGraw-Hill; 2001. 0079130356
Holton JB, Walter JH, Tyfield LA. Galactosemia. In: Scriver CR, Beaudet AL, Sly WS, Valle D, eds. The Metabolic and Molecular Bases of Inherited Disease. 8th ed. New York, NY: McGraw-Hill; 2001: 1553–1588

McCorvie TJ, Timson DJ.
Structural and molecular biology of type I galactosemia: disease-associated mutations.
IUBMB Life. 2011;63(11):949-54. PubMed abstract

Michael Woods.
EBSCO Publishing; (2014) Westside Regional Medical Center website. Accessed on 3/17/2014.

Müller D, Santer R, Krawinkel M, Christiansen B, Schaub J.
Fanconi-Bickel syndrome presenting in neonatal screening for galactosaemia.
J Inherit Metab Dis. 1997;20(4):607-8. PubMed abstract

Ono H, Mawatari H, Mizoguchi N, Eguchi T, Sakura N.
Clinical features and outcome of eight infants with intrahepatic porto-venous shunts detected in neonatal screening for galactosaemia.
Acta Paediatr. 1998;87(6):631-4. PubMed abstract

Openo KK, Schulz JM, Vargas CA, et al.
Epimerase-deficiency galactosemia is not a binary condition.
American Journal of Human Genetics. 2006:89–102. / Full Text
Openo KK, Schulz JM, Vargas CA, et al. Epimerase-deficiency galactosemia is not a binary condition. Am J Hum Genet. 2006; 78: 89–102[CrossRef][ISI][Medline]

Sakura N, Mizoguchi N, Ono H, Yamaoka H, Hamakawa M.
Congenital biliary atresia detected as a result of galactosemia screening by the Beutler method.
Clin Chim Acta. 2000;298(1-2):175-9. PubMed abstract

Segal S. .
Galactosaemia today: the enigma and the challenge - Komrower Lecture.
J Inherit Metab Dis.. 1998; (21):455-471. Netherlands.: SSIEM and Klower Academic Publishers;
Presents the challenges of managing galactosemia.

Waggoner DD, Buist NR, Donnell GN.
Long-term prognosis in galactosaemia: results of a survey of 350 cases.
J Inherit Metab Dis. 1990;13(6):802-18. PubMed abstract
An international survey of the long-term results of galactosemia treatment and results.

Walter, JH, Collins, JE, Leonard, JV.
Recommendations for the management of galactosemia.
Arch Dis Child. 1999;80:93-96. PubMed abstract / Full Text
Recommendations for the evaluation and management of galactosemia. Despite being written in 1999, still contains pertinent information; from the UK Galactosemia Screening Group.

Widger J, O'Toole J, Geoghegan O, O'Keefe M, Manning R.
Diet and visually significant cataracts in galactosaemia: is regular follow up necessary?.
J Inherit Metab Dis. 2010;33(2):129-32. PubMed abstract

Zlatunich CO, Packman S.
Galactosaemia: early treatment with an elemental formula.
J Inherit Metab Dis. 2005;28(2):163-8. PubMed abstract
Discussion about an infant whose erythrocyte galactose 1-phosphate (gal-1-P) levels remained well above the treatment range on a low-galactose (soy) formula.