GALACTOSEMIA :- genetic metabolism disorder.

1. JIWAJI UNIVERSITY
CENTER FOR GENOMICS
MOLECULAR & HUMAN GENETICS
Akansha Chauhan
3rd Semester

2. GALACTOSEMIA

3. CONTENTS BRIEF:
• Introduction
• Leloir pathway
• Types of Galactosemia
• Diagnosis
• Treatment

4. INTRODUCTION
• Galactosemia : “too much galactose in the blood”.
• Galactosemia is a rare genetic metabolic disorder that affects
how the body processes a simple sugar called galactose i.e.
inability of the body to use galactose to produce energy.
• It was first discovered by the physician Von Ruess in 1908.
• It was first recognized & described in detail in 1935 by Manson
& Turner.
• The defected gene that caused it was found in 1956.
• It affects 1 in every 55,000 newborns.

5. GENETIC ETIOLOGY
• Mutation of GALT gene that results to the lack of enzyme –
galactose-1-phosphate uridylyltransferase
• Mutation of GALK1 gene that results to the lack of enzyme –
galactokinase 1
• Mutation of GALE gene that results to the lack of enzyme –
UDP galactose epimerase

6. LELOIR PATHWAY
• Leloir pathway is named after Luis Federico Leloir.
• It is a metabolic pathway for the catabolism of D-galactose.
• It consists of three enzymes:-
sciencedirect.co

7. TYPES OF GALACTOSEMIA
Type 1
Type 2
Type 3

8. TYPE 1 GALACTOSEMIA
• Galactosemia is due to deficiency of the enzyme galactose 1-
phosphate uridylyl transferase.
• It is a rare congenital disease in infants, inherited as autosomal
recessive disorder.
• Mutation in the GALT gene located on chromosome 9 is responsible
for this disorder.
• Galactose metabolism is impaired leading to increased galactose
levels in blood (galactosemia) and urine (galactosuria).
• Accumulated galactose is diverted for production of galactitol by
the enzyme aldol reductase. Galactitol has been implicated in the
development of cataract.

9. CONTINUED
• The accumulation of galactose 1-phosphate and galactitol in
various tissues like liver, nervous tissue, lens and kidney leads to
impairment in their function.
• The accumulation of galactose 1-phosphate in liver results in the
depletion of inorganic phosphate for other metabolic functions.
ucsfhealth.org

10. TYPE1
• Inheritance
 Autosomal recessive
• Features
 Galactosemia
 Galactosuria
 Cataract
 Mental retardation & liver
damage
 Jaundice
 Hypoglycemia
 Aminoaciduria
ufhealth.org

11. TYPE 1
• Diagnosis
 Cataract
 Galactose in urine & blood
 Prenatal Testing:- A doctor can determine during a woman’s
pregnancy whether her baby has galactosemia through:
 Amniocentesis:-This procedure involves using a needle to
withdraw a sample of amniotic fluid from the womb, & then
examining the cells.
 Chronic villus sampling
 New Born Screening:-Babies are tested for Galactosemia at
birth using a tiny blood sample taken from the baby’s heel, the
test for low level of the GALT enzyme.

12. TYPE 2
• Defect in the enzyme galactokinase responsible for
phosphorylation of galactose.
• Mutation in GALK1 gene.
• Galactose is shunted to the formation of galactitol.
• Cataract development at a very early age, sometimes within an
year after birth.
• Treatment involves removal of galactose and lactose from the
diet.
• Undetectable at birth.

13. TYPE 3
• Extremely rare.
• Caused by mutations in GALE gene.
• Symptoms vary from mild to severe and can include cataracts,
delayed growth and development, intellectual disability, liver
disease and kidney problems.

14. TREATMENT
• The treatment for Galactosemia is the removal of galactose from
diet. All lactose products must be totally avoided. Milk and milk
products contain the most amount of lactose, however it is also
present in other foods such as legumes, organ meats and
processed meats.
• Infants will need to be fed with food that is lactose free such as
soy formula, meat-base formula, or Nutramigen.
• There is no definite cure for Galactosemia, the condition is life
long and it can only be controlled. Doctors advise a calcium
supplement for patients with Galactosemia as Milk is an
important source of calcium for a growing child.

15. CONCLUSION
Galactosemia is a rare genetic autosomal recessive disorder but
important cause of metabolic liver disease. It is linked with
mutations in GALT, GALE, GALK1 genes. When galactosemic infants
feed breast milk, symptoms start appearing soon after birth.
Galactose/Lactose free diet is pre-requisite condition for
galactosemic persons to pass normal life, though long term
complications cannot be prevented because they are independent
of diet. High degree of suspicion and early detection are
mandatory for better outcome, since children require galactose free
diet.

16. REFERENCES
• sciencedirect.com
• researchgate.net
• mountsinal.org
• nutritiontactics.com
• medlineplus.gov
• link.springer.com
• galactosemianetwork.org