GALACTOSE METABOLISM

• DR ROHINI C SANE

• PROFESSOR

• DEPARTMENT OF BIOCHEMISTRY

• DR D Y PATIL MEDICAL COLLEGE

• EBENE

GALCTOSEMIA

• INBORN ERROR OF METABOLISM

• BABIES WITH DEFECT CANNOT UTILISE GALACTOSE

• GALACTOSE FROM MILK –PART OF MILK –ONLY FOOD OF BABIES

• NORMAL CONDITION –GALACTOSE CONCENTRATION IN SYSTEMIC BLOOD –NIL

• GALACTOSEMIA –HIGH LEVEL OF GALACTOSE IN BLOOD

SOURCES OF GALACTOSE• INTESTINAL HYDROLYSIS OF DIETARY LACTOSE PRESENT IN MILK

• IMPORTANCE OF GALACTOSE –ESSENTIAL FOR FORMATION OF CERTAIN

GLYCOPROTEINS,CERBROSIDES ,MILK DURING LACTATION

LACTOSE +LACTASE GLUCOOSE +GALACTOSE

ABSORPTION OF LACTOSE - ACTIVE TRANSPORT IN INTESTINAL LUMINAL CELLS

LACTOSE -CARRIED BY PORTAL BLOOD TO LIVER

PORTAL BLOOD THAT ENTERS LIVER CONTAINS GLUCOSE +GALACTOSE +FRUCTOSE

SYSTEMIC BLOOD THAT LEAVES LIVER CONTAINS GLUCOSE + FRUCTOSE

METABOLISM OF GALACTOSE(LIVER)GALCTOSE GLYCOGEN

ATP

ADP GALACTOKINASE (1)

GALCTOSE 1 PHOSPHATE UDP GLUCOSE

GALACTOSE 1 PHOSPHATE UDP GALACTOSE EPIMERASE (3)

URIDYL TRANSFERASE (2)

GLUCOSE 1 PHOSPHATE UDP GALACTOSE

MUTASE

LACTOSE SYNTHETASE

GLUCOSE 6 PHOSPHATE

GLYCOLYSIS LACTOSE

GALACTSEMIA

THREE AUSOMAL RECESSIVE INBORN ERRORS OF GALACTOSE METABOLISM

1. GALACTOKINASE DEFICIENCY

2. GALACTOSE 1 PHOSPHATE URIDYL TRANSFERSE (GALT)

3. GALACTOSE 4 EPIMERASE DEFICIENCY

I GALACTOKINASE DEFICIENCY

• GALACTOSE +ATP+ GALACTOKINASEGALACOSE 1 PHOSPHATE

• CHARACTRISTICS

• ACCUMULATION OF GALACTOSE IN BLOOD & TISSUES

• CATARACT FORMATION DUE TO REDUCTION OF GLUCOSE BY ALDOSE REDUCTASE TO GALACTIOL( DULCITOL)---LENSE BECOMES IMPERABLE

•

GALACTOSE 1 PHOSPHATE URIDYL TRANSFERSE (GALT)

• INCIDENCE : 1 IN 50000 BIRTHS

• ENZYME DEFICIENCY : GALACTOSE 1 PHOSPHATE URIDYL TRANSFERSE (GALT)

• ACCUMULATION OF GALACTOSE & GALACTOSE -1-PHOSPHATE

• CLINICAL AND BIOCHEMICAL FEATURES

VOMITING & DIARRHOEA WITH FAILURE TO THRIVE

HYPOGLYCEMIA

JAUNDICE ,HEPATOMEGALY,CIRRHOSIS

IRREVERSIBLE MENTAL RETARDATION

RENAL TUBULAR DAMAGE &GENERALISED AMINOACIDURIA (FANCONI SYNDROME )DUE TO GALACTOSE- 1 -PHOSPHATE IN KIDNEY

BACTERIAL SEPSIS WITH E .COLI LEADING TO DEATH

III GALACOSE- 4- EPIMERASE DEFICIENCY

• VERY RARE AND ASYMPTOMATIC

• ENZYME MAY BE FOUND DEFICIENT IN ERYTHROCYTES BUT FOUND IN LIVER

MANAGEMENT OF GALACTOSEMIA• ALL THREE TYPES OF GALACTOSEMIA CAN BE TREATED BY

ELIMINATION OF GALACTOSE IN DIET (MILK & MILK PRODUCTS )

THANK YOU