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Q: How many cases of CDG are known worldwide?
A:  We have no exact figures but the published cases figure around 500 for the N-glycosylation disorders. There are many more patients reported with a known O-glycosylation disorder (multiple exostoses, Walker-Warburg syndrome, muscle-eye brain disease etc) but again it is very difficult to obtain exact figures. All together (known and unknown CDG) I guess that an incidence of 1 in 5000 births may be a minimum estimate. Nothing really new happened during the last months but there are new COG defects in the pipeline.  Responder: - Jaak Jaeken, MD, Ph.D 3/18/05

Q: How many cases of CDG are known in the United States?
A:  In the US, my guess is that there is close to 100 cases. I have seen 35-40 here (NIH) and have touched base medically with 20 -25 others. I am certain that I do not speak with all of the families or doctors caring for them, especially if the child is doing well.  Responder: - Donna Krasnewich M.D., Ph.D. 03/18/05

Stroke-Like Episodes

 Responder: - Jaak Jaeken, MD, Ph.D 04/06/05

Q: What is a stroke-like epsisode?
A:  A stroke-like episode is an acute event that very much resembles a stroke. A stroke is a sudden loss of consciousness due to an acute vascular disturbance caused by the rupture of an artery in the brain or its obstruction by a blood clot (embolism or thrombosis); we think that in CDG these episodes are due to a transient local thickening of blood. It can present in several ways: drowsiness, dulness, subcoma, coma, paralysis (on one side(hemiparesis, hemiplegia) or on both sides), loss of vision.

Q: What is the difference between a stroke-like episode and a seizure?
A:  A seizure is the expression of an abnormal electrical activity in the brain (stroke is a vascular problem) but can resemble very much a stroke.

Q: Who is likely to have a stroke-like episode and when are they likely to occur?
A:  In the CDG field all the patients with CDG-Ia have an increased risk for thrombosis because their blood platelets have an increased tendency to stick together and to stick to the wall of blood vessels; for the other CDG-I patients this risk is probably also increased but this has not yet formally been proven also because we know only a small number of these patients. These episodes are most likely to occur on occasion of an infection (viral or bacterial); so these episodes are often accompanied by fever.

Q: Are there ever any long lasting effects?
A:  The positive feature is that, as a rule, these episodes are transient; they can last for hours, days or sometimes even longer.

Q: What action should parent's take during one of these episodes?
A:  Action to be taken: measure body temperature and ask your (or another) physician to examine your child as soon as possible in order to make the diagnosis and to take appropriate measures.

Q: Is there a suggested therapy to prevent or help these episodes?
A:  Medical treatment and prevention are possible but it is up to the physician to decide about the treatment.

Information on Carbohydrates

Responder: - Hudson Freeze, Ph.D.  Adapted from Biochemistry, Typing, Therapy and Your Child.

Q: What is a Carbohydrate?
A:  When most people hear the term carbohydrate, they think of food, diets and energy. Of course this is true, but in the case of CDG we use this term in a special way.  A carbohydrate is a type of molecule composed of carbon, hydrogen, and oxygen and sometimes nitrogen in a certain arrangement.   Table sugar, starch, sea weed products, wood, and corn syrup are all examples of carbohydrates.  Table sugar is composed of two simple sugar units (monosaccharides), glucose and fructose, that are linked together.  Milk sugar is also composed of two sugars, glucose and galactose, linged together.   The ending "ose" denotes a sugar.  Simple sugar units such as glucose, galactose, mannose, xylose, fructose and several others are called monosaccharides.   Starch is an immense molecule composed of thousands of glucose units linked to each other.  The body is well equipped for chipping off glucose units one at a time and using them for metabolic energy - that includes everything from hard exercise to reading in bed.  You always need glucose for energy.

Glycogen, a close relative of starch, is the stored form of glucose.  It may be surprising, but wood and cotton are also carbohydrates - again thousands of glucose units linked to each other.  The difference of course is that these are not food for us.   The reason is that the glucose units are linked differently than in starch or glycogen.  This makes all the difference.  We break down starch because we have the necessary enzymes for doing that very specific job.  We lack the enzymes that break down the celluose in wood and cotton.  Enzymes are proteins that facilitate the transformation of one molecule into another.

Alll living organisms are constantly breaking down some molecules and reshaping them into new molecules they need.   When it comes to carbohydrates, the body will break down some of it for energy, it will store some of it as a glycogen or it may convert some into different sugars.  For instance, glucose can be remodeled into mannose using a few enzymes that reshape it one step at a time.   Glucose can be made into galactose and vice versa.
Responder: - Hudson Freeze, Ph.D.  Adapted from Biochemistry, Typing, Therapy and Your Child. 

Q: Why do we have all these different Carbohydrates?
A:  The answer is that we also use carbohydrates for other things besides making energy.  The entire surface of cells in the body is covered with sugar.  But these sugars have a different function than those supplying energy.  These sugars usually occur in chains having 3-15 sugar units including combinations of mannose, glucose, galactose, and others.  These chains store and convey information about the cell, such as what other cells it attracts or repels, or state of growth of the cell.   Most of these sugar chains are linked to proteins that reside within the cell, at the cell surface, or even circulating free in the blood.  The special proteins are called glycoproteins.  Some fatty substances (lipids) in the body also have sugar chains attached to them and are called "glycolipids".   Other proteins have glycolipids attached to them and also have other sugar chains added directly to them, making these glycoplid (anchored) glycoprotiens.   There are literally thousands of different sugar structures in the body and their location, type and function differ depending on the glycoprotein, and what cell makes it.

The important message here is that the carbohydrates used for energy are different than the carbohydrates used for cell communication, identification, and embryonic development.  Many sugars can be interconverted, but they need several different steps to make this transformation.  Sometimes one of the enzymes required for the interconversion of simple sugars or the assembly of chains is defective.   When this happens it causes big problems - CDG.

Disclaimer: This is a forum for the free expression of ideas created by, and for, parents of children diagnosed with Congenital Disorder of Glycosylation.  The information provided on this web site should NOT be used as a substitute for seeking professional medical diagnosis, treatment and care. You should not rely on any information in these pages to replace consultations with qualified health professionals.
The CDG Family Network,  Attn: Cynthia Wren-Gray,  P.O. Box 860847,  Plano,  Texas, 75074   Phone: 800-250-5273