The gene aberrant in dentinogenesis imperfecta is:

 # The gene aberrant in dentinogenesis imperfecta is:

A. Chromosome 4

B. Chromosome 13

C. Chromosome 21

D. Chromosome 24

The correct answer is A. Chromosome 4.

Aberration in chromosome 4 (4q21.3) is associated with Dentinogenesis imperfecta. It encodes dentin specific sialophosphoprotein (DSPP) gene. Deficiency of sialoprotein is also suggested as a causative factor for DI. They are generally tulip shaped. 

Chromosome number              Disease 

1                                               Vanderwoude syndrome

4                                               Dentinogenesis Imperfecta 

4                                               Cherubism

15                                             Marfan's syndrome

19                                             Osteogenesis imperfecta

Deficiency of which vitamin causes glossitis, dementia, rough keratotic areas on skin and gastrointestinal symptoms?

 # Deficiency of which vitamin causes glossitis, dementia, rough keratotic areas on skin and gastrointestinal symptoms?

A. Riboflavin

B. Pyridoxine

C. Niacin

D. Pantothenic acid

The correct answer is C. Niacin.

Pellagra is a disease caused by a lack of the vitamin niacin (vitamin B3). Symptoms include inflamed skin, diarrhea, dementia, and sores in the mouth. Areas of the skin exposed to either sunlight or friction are typically affected first. Over time affected skin may become darker, stiffen, peel, or bleed.

There are two main types of pellagra, primary and secondary. Primary pellagra is due to a diet that does not contain enough niacin and tryptophan. Secondary pellagra is due to a poor ability to use the niacin within the diet. This can occur as a result of alcoholism, long-term diarrhea, carcinoid syndrome, Hartnup disease, and a number of medications such as isoniazid. Diagnosis is typically based on symptoms and may be assisted by urine testing. 

FIGLU excretion test is used to estimate deficiency of:

 # FIGLU excretion test is used to estimate deficiency of:

A. Vitamin K

B. Vitamin B12

C. Vitamin Folic acid

D. Niacin

The correct answer is C. Vitamin Folic acid.

Folic acid is associated with the metabolism of histidine. Formiminoglutamate (FIGLU) formed in histidine metabolism accumulates and is excreted in urine. Histidine load test utilizing the excretion of FIGLU in urine is used to assess folic acid deficiency. 

Which of the following vitamins is destroyed by heat?

 # Which of the following vitamins is destroyed by heat?

A. Vitamin A

B. Vitamin D

C. Biotin

D. Thiamin

The correct answer is C. Biotin.

Biotin is present in many foods, including liver, grains, and eggs. It is also synthesized by intestinal bacteria. The conversion to a coenzyme simply requires that it be covalently linked to the appropriate enzymes. Biotin acts as a carrier of "activated carboxyl" groups for three key enzymes that catalyze carboxylation reactions. The enzymes and the pathways they participate in are: Pyruvate carboxylase (gluconeogenesis), acetyl-CoA carboxylase (fatty acid synthesis), and propionyl-CoA carboxylase (branched chain amino acid catabolism). Biotin deficiency is rare. Excessive consumption of raw egg impairs biotin absorption due to the presence of a biotin-binding protein, avidin, in egg whites. Antibiotics that alter the intestinal flora can also lead to biotin deficiency. Symptoms of deficiency include alopecia, skin and bowel inflammation, and muscle pain.