Pharma gyan Pandit

Enzyme Deficient Diseases:

Galactosemia:

A genetic disease in which the body has an inability to metabolize galactose.  Elevated levels of galactose in blood and urine along with vomiting, diarrhea, liver enlargement are signs of this disease.  Can cause death in days is lactose is not removed from their diet

Albinism:

Lack of the enzyme tyrosinase which increases the rate of melanin production of the skin.  UV light is the main regulator of this enzyme.  Increased exposure to UV causes activity of tyrosinase to begin.  This escalates the rate of melanin production resulting in a tan. 

Lactose Intolerance:

Lactose intolerance develops when the body has difficulty digesting whole and skim milk and other dairy products. Lactose is a milk sugar and like most sugars, it is broken down by enzymes in the intestinal tract so it can be absorbed as an energy source. The enzyme that breaks down lactose is called lactase. When the intestine does not contain lactase, then lactose intolerance can occur. It is a troublesome and annoying problem, but it is never a serious one.

As commonly expected, infants and small children have the enzyme lactase so they can digest mothers' milk. However, during childhood, lactase begins to disappear in many people. Some ethnic groups are more likely to develop lactose intolerance. By adolescence, it is gone in about 75% of African-Americans, Jews, Native Americans, Mexicans, and in 90% of Asians. So the condition is very common.

When undigested lactose reaches the colon (large intestine), it is broken apart by bacteria. Lactic acid and other acidic chemicals result. It is these products that create the symptoms of lactose intolerance. These symptoms include nausea, abdominal cramps and rumbling, bloating, rectal gas (flatus), and diarrhea. They usually occur 30 minutes to two hours after ingesting lactose-containing foods. The severity of symptoms usually depends on the amount of lactose ingested and how much of the enzyme, lactase, remains in the intestinal tract.

Tay-Sachs Disease:

This disorder is named after a physician, Dr Bernard Sachs, who noted in 1887 that a number of children of Central and Eastern Europe (Ashkenazic) Jewish ancestry, who were born with no apparent problems, degenerated physically and mentally and died by the age of about four.  The affected children were found to have a cherry-red spot at the back of the eye by an ophthalmologist, Dr Warren Tay, and thus the condition became known as Tay-Sachs disease.

The symptoms first appear at about the age of 6 months when an apparently happy healthy baby stops smiling, crawling or turning over, loses its ability to grasp or reach out, and gradually becomes blind, paralyzed and unaware of his/her surroundings.  Death usually occurs by the age of 3 or 4 years.

Babies born with this condition lack a particular enzyme called hexosaminidase A or Hex A.  Hex A normally breaks down a fatty substance found in the brain called GN12 ganglioside.  Small amounts of this substance are essential for proper brain function. In a child with Tay-Sachs disease, the Hex A enzyme is missing and the fatty substance accumulates in the brain cells, irreversibly damaging the cells.

The mutation causing Tay-Sachs is in a gene on a chromosome and its effects are "recessive" or hidden by the presence of the correct copy of the gene.  The pattern of inheritance in families who have this mutation is thus described as autosomal recessive inheritance  There are four possibilities for the combinations of genes passed from the parents.

If a couple who are both carriers of a mutation in their Hex A gene have a baby, there is a 25% chance, in every pregnancy, that they will have a baby who is affected with Tay-Sachs disease.

If only one of the parents is a carrier of the mutation, there is no chance that the baby will inherit the mutation causing Tay-Sachs disease but there is a 50% chance that their child will be a healthy carrier of the mutation.