The cause genetics of spinal muscular atrophy(SMA) in cats Maine Coon ,was determined in may 2005, culminating in a cooperative effort, eight years of breeders, veterinarians and researchers at the University of the State of Michigan, the University of California at San Diego, the national center for the information of the biotechnology and the national cancer institute.Spinal Muscular Atrophy is a motor neuron disease. The motor neurons affect the voluntary muscles that are used for activities such as crawling, walking, controlling the neck and head, and swallowing.
SMA affects muscles throughout the body, while the muscles in the proximal (those that are located closer to the trunk, as for example the shoulders, hips, and back) are often most severely affected. Weakness in the legs is generally greater than in the arms. Sometimes eating and swallowing can be affected. The muscles involved in breathing (the muscles related to breathing and coughing) can show an increased tendency to suffer from pneumonia or other lung problems.
The loss of neurons in the first few months of life leads to weakness and muscle atrophy is apparent at 3-4 months of age. The kittens affected develop a step-odd with a shaking of the rear quarters. Can it stand with the toes of the feet outward . With 5-6 months of age, the rear quarters are too weak, they struggle to jump easily up to the furniture and often have a landing clumsy to jump down. The long hair of the Maine Coon,you can hide it, but the feedback of members disclose the mass-reduced muscle. The kittens affected do not have pain, eat and play avidly, they are not sad, and most live very comfortably as indoor cats for years.
The SAM is a genetic disease of autosomal recessive inheritance. For that a kitten can be affected by SAM, both parents must be carriers of the abnormal gene and both must pass on this gene to the kitten. Although both parents are carriers, the chance that a child will inherit the disorder is 25%.
.An individual with SAM has a mutated or missing gene (SMN1, or survival motor neuron 1 neuron – motor survivor 1) that produces a protein in the body called a Neuron Motor Survivor NMS (Survival Motor Neuron – SMN). The deficiency of this protein has your love more severe in motor neurons. Motor neurons are called the cells of nerve in the spinal cord, which send nerve fibers to the muscles of the whole body. Given that the protein NMS is critical to the survival and health of motor neurons, without this protein, the cells nerve may atrophy, shrink and eventually die, resulting in muscle weakness. While a baby with SAM is going to grow ,your body is strained twice, first by the decrease in motor neurons and, then, by the increased demand in the cells of nerve and muscle as your body grows. Muscle atrophy resulting can cause weakness and deformities bone and spinal that we may incur in the loss of other functions, as well as an additional commitment of the respiratory system.
There are four types of SAM:(But here we talk about in humans, the symptomatology is similar to in Maine Coons affected)
TYPE I. The diagnosis of children with this type is usually made before 6 months of age and in the majority of cases, the diagnosis is made before 3 months.Usually, a child with type I is never able to lift his head or achieve the goals of motor to be expected in a child. They usually have little control of their head and can not hold the weight in your legs. . Chewing and swallowing may be difficult. The tongue may show atrophy and movements wavy or fine tremor, also called fasciculations. There is weakness of the muscles intercostals (the muscles between the ribs) that help to expand the chest, and the chest is usually smaller than usual. The muscle respiratory stronger in a patient with SAM is the diaphragm. As a result, the patient seems to breathe with the muscles of his stomach. The chest may appear concave (sunken) due to the breathing diafragmatica (stomach). Also, due to this type of breathing, the lungs may not develop fully, the cough is very weak, and it can be hard to take breaths deep, while you sleep to maintain normal levels of oxygen and carbon dioxide.
TYPE-II.-. Difficulty swallowing are not usually characteristic of this Type II. Some patients may have difficulty eating enough food per month to maintain their growth and weight, and a feeding tube may be necessary. Children with SAM Type II often have fasciculations in the tongue . We also have weakness of the intercostal muscles and are respirators diafragmaticos. They have difficulty coughing and may have difficulty taking deep breaths while you sleep to maintain normal levels of oxygen and carbon dioxide. Scoliosis occurs almost uniformly in the as these children grow, resulting in the need of a surgery or column corse at some point in their clinical course. The decrease of bone mass can result in an increased susceptibility to fractures.
TYPE III.-It is much more variable in age of onset, and children can be present from about one year of age, up to and including the end of adolescence, even though the diagnosis before 3 years of age is typical. The patient with Type III can stand alone and walk, but may have difficulty with walking at some point in their clinical course. Their indicators engines early are often normal. However, once they begin walking, they may fall frequently, have difficulty getting up from sitting on the floor or a position excessively bent, and may be unable to run. With the Type III, a fine tremor may be observed in the fingers stretched out, but the fasciculations in the tongue are rarely seen. Difficulties in feeding and swallowing are rare. The individuals with type III may sometimes lose the ability to walk to the end of childhood, adolescence or even adulthood, often in association with the stimuli of growth or disease.
TYPE IV.-(adult onset) In the adult form, symptoms typically appear after the age of 35 years. It is rare for the Spinal Muscular Atrophy begins between the ages of 18 and 30 years. The SAM of adult onset is much less common than the other forms. Its start is defined by weakness after the age of 18 years, and the majority of the reported cases as Type IV have occurred after the age of 35 years. It is typically characterized by an insidious onset and progression very slow. The muscles bulbar, those muscles used for swallowing and breathing, are rarely affected in Type IV.
Patients with SAM typically lose function over time. The loss of function can occur rapidly in the context of growth or disease, or much more gradually. The explanation for this loss is unclear, based on recent research. It has been observed that patients with SAM can often be very stable in terms of their functional abilities for long periods of time, even years, although it is almost the universal trend of the continuous loss-of-function as they age.
CURRENTLY, THERE ARE GENETIC TESTS TO ASSESS WHICH ARE MADE IN MAINE COONS, TO DETERMINE IF THEY ARE CARRIERS OR HAVE THE DISEASE.
http://www.fsma.org/
http://www.genome.org/cgi/content/full/16/9/1084
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