What causes Pompe Disease?

Hello guys, I am back!! :D

This week we will be a little more intensive and examine the science behind Pompe. Are you ready?! Of course you are! I can sense your enthusiasm!! XD Now lets get started shall we?

As mentioned in the previous post, Pompe patients are unable to break down glycogen in their cells unlike non-sufferers. But why is that so? Today I am going to answer your question.

First of all lets go to the root of the problem which is the genetics (remember I have mentioned before that the disease is genetic?). There is one gene in your genome called the GAA gene which codes for the acid alpha-glucosidase enzyme. This is the enzyme which breaks down the glycogen by hydrolysing α-1,4- and α-1,6-glucosidic linkages in glycogen (don't worry if you don't understand this part! It just basically means the enzyme breaks these 2 types of bonds which holds the glycogen molecule together!). However for people with Pompe disease, there is a mutation in the GAA gene which cause a defect in the enzyme production, so no or very little acid alpha-glucosidase is produced.

Both glycogen and acid alpha-glucosidase are found in little packages in muscle cells called lysosomes. The job of alpha-glucosidase is to break down the glycogen in the lysosomes so that the glycogen will take up less space in the lysosomes. But if acid-alpha glucosidase is not present, the amount of glycogen will keep increasing in the lysosomes until the lysosome swells beyond the normal size. This can disrupt cellular functions in the muscle cells and the lysosomes can even burst, damaging the cell and the surrounding tissues. Ouch :(


(http://www.pompe.com/patients/about/cause.aspx)
Here is a picture of what is going on inside a muscle cell of a person suffering from Pompe.
Myofibrils are structures found inside muscle cells that controls muscle contractions.

As you can see, glycogen can be found all over the muscle cell, interfering with the myofibrils and causing disruptions in the cell.  This causes the symptoms of Pompe which includes muscle weakness and breathing difficulties (as respiration is controlled by muscles too).

(http://blogs.lt.vt.edu/joneill/2012/09/17/extraordinary-measures/)

Since Pompe disease is genetic, it can be passed down from generations to generations. This disease is an autosomal recessive disease, meaning that you have to inherit the defective gene from BOTH parents to be affected. Or if only one of your parents carry the disease while your other parent is normal, you will be a carrier and you can pass down the defective gene to your children too. Sounds quite scary doesn't it :(

(http://www.pompe.com/patients/inheriting-pompe.aspx)

 Here is a chart showing how the inheritance of the disease works. Alleles basically means different forms of the same gene. In this case, there is the abnormal allele of the GAA gene which can cause Pompe disease and the normal allele of the GAA gene which won't cause Pompe disease.

*Do note that even though there are different type of Pompe disease (early-onset/late-onset), the basis behind the disease is the same.

Phew, that was lengthy wasn't it. The good news its that this is all we have for now! :D Time to give that brain of yours a break!

If you have any questions regarding what was mentioned in the posts (including this one) please feel free to comment below! We will try to answer your questions and maybe even discuss about it :)

See you next time!

~Mei Ying

References:
http://www.pompe.com/patients/about/cause.aspx
http://themedicalbiochemistrypage.org/pompedisease.php
http://www.pompe.com/patients/inheriting-pompe.aspx

Introduction

Hello everyone, welcome to our new blog!!

This blog was created as part of our Medical Biochemistry module project and we have chosen Pompe disease as our subject of interest. So before we dive into the details lets first do a little self introduction to kick start this journey! :D My name is Mei Ying and my project partner is Rose. What can you expect from the both us the next few weeks you say? Well the title of the blog says it all! Every week the both of us will update the blog by posting some interesting facts or details about Pompe disease. Don't worry if you know nothing about the disease at all because that's what this blog is all about, to understand the disease ;) so if you follow us diligently for the next couple of weeks we will keep you on track on what's goin' on :)

Alrighty, now that the self-introduction part is done we shall satisfy the needs of the knowledge-hungry viewers ;).  So what exactly is pompe disease? Pompe disease is a type of glycogen storage disease. Glycogen is a type of complex carbohydrate and it serve as a store of sugar in our body. After you eat a meal for example, the digested food is converted to glucose which enters your bloodstream. When the level of glucose is high in your blood, your body will convert glucose to glycogen and glycogen will be stored in your cells. Usually, the glycogen will be broken down back to glucose for use later but for people suffering from Pompe disease, the break down doesn't happen and glycogen accumulates in the cells. This can cause damage and affect the functions of the organs!

Pompe disease is an inherited disease so it can be passed down generations, but fear not as this disease is also quite rare (with 1 in 40, 000 births in the US).

There are 3 type of this disease : the classic infantile-onset Pompe disease , the non-classic infantile-onset Pompe disease and the late onset Pompe disease.

Both the classic and non-classic infantile-onset disease affects infants while the late-onset disease affects people in their late childhood, adolescents or even adulthood. The infantlile-onset diseases are often fatal but for the late-onset disease the survival rate is higher. More details about each type will be mentioned in a later post, so stay tuned to find out !

That is all for now, we hope that you have gained more insights on the disease and we once again welcome you on board this journey with us! Adieu~

Mei Ying :)