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Inherited disease PWD GM1- gangliosidosis
2007-05-30| Gangliosidosis belongs to a group of hereditary diseases known as "lysosomal storage diseases". Lysosomes are specific structures inside the cell in which, as in a "sewage plant", many substances are degraded or altered. Molecules carrying out this degrading or altering are called enzymes. With a lysosomal storage disorder, substances that due to an enzyme deficiency cannot be processed are stored in the lysosomes. In the case of gangliosidosis, gangliosides (fat-sugar compounds) build up in the brain cells. Thereby vital cell functions in the brain are mutilated resulting in severe disorder symptoms. Gangliosidosis occurs in two different forms. The GM1 gangliosidosis is caused by an inherited deficiency of the beta-galactosidase enzyme. In this form the neurological symptoms begin slightly later (approx. at 4 months) and proceed more slowly. With GM2 gangliosidosis the beta-hexosaminidase enzyme is missing, the disease pattern normally appears earlier and aggravates quicker. Even though both forms of gangliosidosis have similar symptoms, they are evoked by completely different defects of two specific lysosomal enzymes. These genetic defects known as mutations are due to a modification in the genetic code. What makes both of these diseases pernicious is that they are inherited covertly (autosomal recessive). With this transmission, the illness only breaks out when both formations of a critical gene are defective (as opposed to autosomal dominant inheritance where the illness breaks out when only one critical gene is defective.) The heredity course of gangliosidosis follows the classical laws of genetics. An individual always inherits a gene copy from the dam and one from the sire. A recessive heredity course means that dogs carrying just one copy of the defective gene (i.e. they are heterozygote) are clinically healthy but are carriers. Carriers themselves will never get this disease but there is a 50% chance that they will pass the defective gene on to their offspring. Only if two copies of the defective gene (from dam and sire) exist, i.e. the puppy is homzygous, will the disease break out. If carriers are mated, 25% of their offspring will statistically get gangliosidosis, 50% will be carriers and 25% will be free of the defective gene. Even when mating hereditarily sound dogs and carriers caution should be exercised. There is no chance of offspring being affected by gangliosidosis but with a probability of 50% carriers will be produced. Thereby the defective gene can be spread unwittingly in the dog population. Thanks a lot for this link Dr. Holger Funk. More informations you will find here.
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