Galactosemia type 1

=Galactosemia Type 1 = Galactosemia Type 1, also known as Classic Galactosemia, is a rare genetic metabolic disorder that affects an individual's ability to metabolize the sugar galactose properly. This condition is caused by a deficiency in the enzyme galactose-1-phosphate uridylyltransferase (GALT), which is crucial for the proper conversion of galactose into glucose.

Pathophysiology

Galactosemia Type 1 is an autosomal recessive disorder, meaning that an individual must inherit two defective copies of the GALT gene, one from each parent, to manifest the disease. The GALT enzyme is responsible for the second step in the Leloir pathway of galactose metabolism, converting galactose-1-phosphate and UDP-glucose into UDP-galactose and glucose-1-phosphate. In the absence of functional GALT, toxic levels of galactose-1-phosphate accumulate in tissues, leading to the symptoms of the disease.

Symptoms

Symptoms of Galactosemia Type 1 typically appear shortly after birth and can include:

• Jaundice
• Hepatomegaly (enlarged liver)
• Cataracts
• Vomiting
• Diarrhea
• Failure to thrive
• Sepsis

If untreated, the condition can lead to severe complications such as liver damage, intellectual disability, and even death.

Diagnosis

Diagnosis of Galactosemia Type 1 is often made through newborn screening programs, which test for elevated levels of galactose or galactose-1-phosphate in the blood. Confirmatory testing involves measuring GALT enzyme activity in red blood cells or genetic testing to identify mutations in the GALT gene.

Treatment

The primary treatment for Galactosemia Type 1 is a strict galactose-free diet, which involves eliminating lactose-containing foods such as milk and dairy products from the diet. This dietary management must be maintained throughout the individual's life to prevent the accumulation of toxic metabolites.

Prognosis

With early diagnosis and strict dietary management, individuals with Galactosemia Type 1 can lead relatively normal lives. However, some may still experience long-term complications such as speech difficulties, learning disabilities, and ovarian failure in females.

Genetics

The GALT gene is located on chromosome 9p13. Mutations in this gene can vary, with the most common being the Q188R mutation in Caucasian populations. Genetic counseling is recommended for families affected by Galactosemia Type 1 to understand the inheritance pattern and risks for future pregnancies.

Research

Ongoing research in Galactosemia Type 1 includes studies on enzyme replacement therapy, gene therapy, and the development of alternative dietary treatments. Researchers are also investigating the long-term outcomes of individuals with the condition to improve management strategies.

See Also

• Galactosemia Type 2
• Galactosemia Type 3
• Lactose intolerance

External Links

• Galactosemia Foundation
• National Organization for Rare Disorders

NIH genetic and rare disease info

• NIH info on Galactosemia type 1

Galactosemia type 1 is a rare disease.