Question

Galactosemia is a potentially fatal disease that occurs in humans who lack the enzyme that converts galactose to glucose. If you were a physician treating a person with this disease, which of the following would you have them exclude from their diet? a. maltose b. starch c. mannose d. lactose

Short answer

A person with Galactosemia should exclude option d (lactose) from their diet, as lactose is a disaccharide sugar containing one galactose and one glucose molecule. The individual lacks the enzyme to convert galactose to glucose, making lactose dangerous for them to consume.

Step-by-step solution

Understand Galactosemia

Galactosemia is a genetic disorder in which a person has difficulty processing the sugar galactose. This is because they lack the enzyme necessary to convert galactose to glucose, a simpler sugar that the body can then use for energy. The main source of concern for individuals with Galactosemia is the consumption of food containing galactose.

Examine each option

The sugars in the given options are: a. maltose: a disaccharide sugar made of two glucose molecules b. starch: a complex carbohydrate made of many glucose molecules c. mannose: a monosaccharide sugar similar in structure to glucose d. lactose: a disaccharide sugar made of one galactose and one glucose molecule

Identify the sugar containing galactose

Among the options, only lactose (option d) contains galactose. Lactose is a sugar found in milk and dairy products and is made up of one galactose molecule and one glucose molecule. Patients with Galactosemia lack the enzyme to process the galactose part of lactose, which makes consuming lactose dangerous for them.

Conclusion

Since lactose contains galactose, which the person with Galactosemia cannot properly process, the correct choice is to have them exclude option d (lactose) from their diet.

Key concepts

Genetic Disorder

Galactosemia is an example of a genetic disorder, which means it is a condition passed down from parents to their offspring through genes. This condition is caused by mutations in specific genes that affect the body's ability to process certain substances. In the case of galactosemia, the body lacks the enzyme needed to convert galactose into glucose.
Genetic disorders like galactosemia are typically inherited in a recessive manner. This means a person must inherit two copies of the faulty gene - one from each parent - in order to express the disorder. These disorders can manifest in a variety of physical, developmental, or metabolic issues, which may require special attention from medical professionals.
Understanding genetic disorders is key for devising effective treatment strategies and for providing genetic counseling to families at risk of passing these conditions on to their children.

Dietary Management

For individuals with galactosemia, dietary management is crucial. Since their bodies cannot properly process galactose, avoiding foods that contain this sugar can prevent serious health complications. The primary dietary restriction for galactosemia is the exclusion of lactose-containing food products.
Effective dietary management involves:

• Avoidance of dairy products and foods containing milk or milk derivatives.
• Careful reading of food labels to check for hidden sources of galactose, such as casein or whey.
• Working with dietitians to create a balanced diet that meets nutritional needs without exposure to galactose.

Adhering to such dietary restrictions can significantly reduce the risk of symptoms and improve the quality of life for those with galactosemia.

Enzymatic Deficiency

Enzymatic deficiency refers to the lack of specific enzymes needed to conduct biochemical reactions in the body. In galactosemia, the deficiency lies in enzymes such as galactose-1-phosphate uridyltransferase, which are necessary for the proper metabolism of galactose.
When these enzymes are missing or non-functional due to genetic mutations, the body cannot convert galactose to glucose. This causes an accumulation of galactose in the blood and body tissues, leading to symptoms like jaundice, liver damage, and developmental issues.
It is important to identify such deficiencies early on through neonatal screening programs, which can help in managing the disorder effectively before severe complications arise.

Lactose Metabolism

Lactose metabolism is the process by which the disaccharide lactose is broken down into glucose and galactose. Normally, the enzyme lactase in the small intestine initiates this process by splitting lactose into its two component monosaccharides.
For individuals with galactosemia, even though lactase functions normally, the issue arises in metabolizing galactose further due to the absence of necessary enzymes. Consequently, the galactose accumulates, causing toxic effects.
Understanding lactose metabolism is critical for managing conditions like galactosemia and lactose intolerance. In both cases, dietary adjustments are necessary to ensure the body does not suffer from unmetabolized lactose or its by-products.