Galactosemia
Other Names
Classic galactosemia
Duarte galactosemia
Galactose-1-phosphate uridyl-transferase deficiency disease
Galactokinase (GALK) deficiency disease
UDP-galactose-4-epimerase (GALE) deficiency disease
Overview
Galactose is found in many foods and is produced when lactose is split by lactase into glucose and galactose. Three enzymes are involved in the metabolism of galactose into uridine diphosphate (UDP)-glucose and, ultimately, to carbon dioxide. Mutations of each of these genes can result in galactosemia:- Galactose-1-phosphate uridyl-transferase (GALT) deficiency results in Classic Galactosemia, where homozygotes have less than 5% enzyme activity. Duarte variant galactosemia, with between 10% and 25% activity, results from the compound heterozygote state with a GALT mutation and a Duarte allele.
- Galactokinase 1 (GALK1) deficiency may cause cataracts and pseudotumor cerebri. These individuals have normal GALT enzyme activity.
- UDP-galactose-4-epimerase (GALE) deficiency can cause a benign form, in which the deficiency is found only in red blood cells and no symptoms result, and a severe form, in which the deficiency affects most tissues resulting in symptoms similar to classic galactosemia. These individuals have normal GALT enzyme activity.
Incidence
Classic galactosemia occurs in about 1 in 30,000 live births; Duarte variant occurs in about 1 in 16,000.Prenatal Testing
DNA testing possible by amniocentesis or chorionic villus sampling (CVS) if both disease causing mutations of an affected family member have been identified. GALT enzyme activity is also possible.Other Testing
Genetic testing is possible for at-risk family members if both disease causing mutations of an affected family member have been identified. Carrier testing by measuring GALT enzyme activity for at-risk family members is also possible.Clinical Characteristics
For classic galactosemia, symptoms develop shortly after starting to ingest milk or other lactose containing foods. With treatment, good health may be expected. Even with therapy, some patients with classic (G/G) galactosemia can have speech defects, poor intellectual function, neurologic deficits (predominantly extrapyramidal findings with ataxia), and ovarian failure with primary amenorrhea or early menopause. Without treatment, hepatic and neurologic injury and increased risk of sepsis may lead to death.Initial signs/symptoms may include:
- Poor feeding
- Vomiting
- Diarrhea
- Jaundice
- Bleeding diasthesis
- Lethargy
- Abdominal distention with hepatomegaly
- Increased risk of sepsis with gram negative organisms
- Progressive liver failure
- Cataract
- Brain damage
Follow-up Testing after Positive Screen
Patients with a positive screening test (GALT activity level < or = 2.0 U/gHb) or who are symptomatic should be on a lactose/galactose free diet until the galactose-1-phosphate uridyltransferase enzyme level and the galactosemia DNA panel has been completed. Patients with a positive screening test with a GALT activity level >2.0 do not need dietary change. If the galactose-1-phosphate uridyltransferase and the Utah galactosemia DNA panel is consistent with classical galactosemia (GG genotype with low activity level) dietary restriction of galactose should continue. All other genotypes, including Duarte galactosemia (DG), do not require dietary restriction. In DG, the galactose-1-phosphate level may be elevated in the first year of life, but no deficits occur.Primary Care Management
Upon Notification of the + Screen
- Contact the family and evaluate the infant for related symptoms.
- Provide emergency treatment/referral for symptoms of poor feeding, lethargy, jaundice, vomiting, bulging fontanel.
- Discontinue breast or cow milk formula feeding, start feeding with Prosobee or Isomil soy formulas.
- To confirm the diagnosis, work with the following service(s): Newborn Screening Services (see NW providers [1]).
- For evaluation and ongoing collaborative management, consult the following service(s): Pediatric Genetics (see NW providers [1]).
If the Diagnosis is Confirmed
- Educate the family regarding signs, symptoms, and the need for urgent care when the infant becomes ill.
- Assist in implementing and maintaining rigid dietary exclusion of lactose and galactose.
- Monitor for developmental delays, speech delay, and, in females, ovarian failure.
- For those identified after irreversible consequences, assist in management, particularly with developmental and educational interventions.
Specialty Care Collaboration
Initial consultation with the following service(s): Pediatric Genetics (see NW providers [1]). Ongoing collaboration if the child is affected. Genetic counseling for the family.Resources
Information & Support
For Professionals
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.
For Parents and Patients
Galactosemia (MedlinePlus)
Information for families that includes description, frequency, causes, inheritance, other names, and additional resources;
from the National Library of Medicine.
Galactosemia Foundation
Provides information about galactosemia and facilitates networking among families, clinicians, and researchers.
Resources for Galactosemia (Disease InfoSearch)
Compilation of information, articles, research, case studies, and genetics links; from Genetic Alliance.
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.
Tools
ACT Sheet for Classical Galactosemia (ACMG)
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)
Contains short-term recommendations for clinical follow-up of the newborn who has screened positive; American College of Medical
Genetics.
Services for Patients & Families Nationwide (NW)
| Service Categories | # of providers* in: | NW | Partner states (6) (show) | | ID | MT | NM | NV | RI | UT | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Newborn Screening Services | 1 | 22 | 4 | 1 | 2 | 1 | 3 | ||||
| Pediatric Genetics | 1 | 3 | 7 | 4 | 4 | 4 | 6 | ||||
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.
Helpful Articles
PubMed search for galactosemia and neonatal screening, last 5 years.
Freer DE, Ficicioglu C, Finegold D.
Newborn screening for galactosemia: a review of 5 years of data and audit of a revised reporting approach.
Clin Chem.
2010;56(3):437-44.
PubMed abstract