Robbie Jenkins is a four year old boy growing up in Blackwood. He is small for h

Question

Robbie Jenkins is a four year old boy growing up in Blackwood. He is small for his age and seems to be growing slowly compared to his friends. Recently, he has been complaining of abdominal pain and he sometimes has diarrhoea. The stool that he passes is watery and floats in the toilet bowl. It smells particularly bad. His parents take him to the doctor. The doctor takes a blood sample and has it analysed for "antibodies to tissue transglutaminase" (tTG or TG2). The results are positive. Robbie then undergoes an endoscopy in Flinders Medical Centre. He is sedated and a fibre-optic endoscope is passed down his oesophagus, through his stomach and into his small intestine. It is noted that the villi in his small intestine do not have the normal finger-like shape; they have very little depth so that the mucosa looks almost flat. These are all typical signs and symptoms of coeliac disease. His parents are told to change his diet to avoid gluten. They talk to a nutritionist and make the appropriate changes and his symptoms and signs improve over the next 2 months. (a) What is gluten? (1 mark) (b) Where does tissue transglutaminase come from? (1 mark) (c) What does a "transglutaminse" enzyme do (it's primary role)? (1 mark) (d) Which 3 cereal grains that are most common in the Australia diet contain sufficient gluten to trigger exacerbations of coeliac disease? (1 mark) (e) What is gliadin? (1 mark) (f) Why is Robbie failing to grow at a normal rate? (1 mark) (g) Why do his stools float in the toilet bowl and smell so bad? (1 mark) (h) Why does Robbie have frequent bouts of abdominal pain? (1 mark) (i) Why does Robbie have diarrhoea? (1 mark) (j) Most of us eat lots of gluten and have lots of tissue transglutaminase, yet we don't have celiac disease. There are two specific serotype of an antigen presenting protein (an HLA) that greatly increase someone's risk of developing Coeliac Disease. Which HLA form are they? (1 mark)

Explanation / Answer

A) Gluten is a type of complex proteins made primarily of the storage proteins called prolamins and gluteleins.It is found in a complexr with the starchy endosperm of cereal grains.

B) Tissue transglutaminase is a calcium-dependent ubiquitous enzyme having several physiological functions in the body. It is found as both intra-cellular and extra-cellular secretions in different tissues including the heart, the liver, and the small intestine.

C) The enzyme tissue transglutaminase catalyses posttranslational modification of proteins. It is released by cells during bouts of inflammation. It deamidates and enhances the immunostimulatory role of gluten protein.

D) The gollowing cereals have the highest gluten content in Australia - wheat,barley, rye, triticale and oats.

E) Gliadin is the alcoholo-soluble protein component found in gluten. It is thought to be the primary antigen leading to an inflammatory reaction in the small intestine

F) Shoert stture and abnormal growth can be attributed to the nutritional insufficiency that occurs as a result of constant diarrhea. Additionally, coeliac disease has been found to be co-related with lower levels of growth hormonw secretions, which leads to short stature/stuntung.

G) Since the intestines do not function properly, there is not enough probiotic bacteria, or fibers in the stool to bulken it up. Hence the density is quite low and it floats. Additionally, malabsorbion of nutrients in the intestines leads to foul smell in the stool.

H) Main cause of pain is the inflammation of intestines after eating gluten rich diet. Auto-antibodies against gluten are produced which lead to inflammation of intestines.

I) Diarrhea is often caused due to malabsorption, which is the inability to absorb nutrients from food. The unabsorbed food therefore tends to increase the frequency of bowel movements and lead to diarrhea.

J) Celiac disease has been found to be strongly associated with specific HLA class II genes, which are known as HLA-DQ2 and HLA-DQ8. These genes are located on chromosome 6p21.

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