Spinal Muscular Atrophy is a motor neuron disease. The motor neurons affect the voluntary muscles that are used for activities such as crawling, walking, head and neck control, and swallowing. It is a relatively common "rare disorder": approximately 1 in 6000 babies are born affected, and about 1 in 40 people are genetic carriers.
SMA affects muscles throughout the body, although the proximal muscles (those closest to the trunk) are often the most severely affected. Weakness in the legs is generally greater than in the arms. Sometimes feeding and swallowing can be affected. Involvement of respiratory muscles (muscles involved in breathing and coughing) can lead to an increased tendency for pneumonia and lung infections. Sensation and the ability to feel are not affected. Intellectual activity is normal and it is often observed that patients with SMA are unusually bright and sociable. Patients are usually grouped into one of four categories, based on certain key motor function milestones.
(Autumn was diagnosed with SMA type II).
The diagnosis of type II SMA is almost always made before 2 years of age, with the majority of cases diagnosed before 15 months. Children with this type may sit unsupported when placed in a seated position, although they are often unable to come to a sitting position without assistance. At some point they may be able to stand. This is accomplished with the aid of assistance bracing and/or a parapodium/standing frame. Swallowing problems are not usually characteristic of Type II, but vary from child to child. Some patients may have difficulty eating enough food by mouth to maintain their weight and grow, and a feeding tube may become necessary. Children with Type II SMA frequently have tongue fasciculations and manifest a fine tremor in the outstretched fingers. Children with Type II also have weak intercostals muscles and are diaphragmatic breathers. They have difficulty coughing and may have difficulty taking deep enough breaths while they sleep to maintain normal oxygen levels and carbon dioxide levels. Scoliosis in almost uniformly present as these children grow, resulting in need for spinal surgery or bracing at some point in the clinical course. Decreased bone density can result in as increased susceptibility to fractures.
SMA is diagnosed primarily through a blood test which looks for the presence of absence of the SMN1 (survival motor neuron) gene, in conjunction with a suggestive history and physical examination.
Normally, individuals have two genes called Survival Motor Neuron 1 and 2. In approximately 95% of patients with SMA there is an absence of the SMN gene sequence which is present in normal individuals. Sometimes, the SMN1 gene is not missing, but mutated. The number of copies of SMN2, a near identical backup copy of the SMN1 gene, is related to the severity of the disease, but does not reliably predict a specific SMA type in a given individual. SMA type is generally determined from the clinical examination evaluating the child's degree of weakness and ability to achieve major motor milestones such as sitting independently or walking. Source: Families of FSMA
Autumn has zero copies of SMN1, and three copies of SMN2, as was determined by DNA testing.
Autumn is doing well living with SMA, considering the severity of her diagnosis. So far, slight increases in her physical strength have been observed, and as of January 2008, it appears that her disease is not yet progressing. She is able to sit independently for as long as she wants, and lowers herself to the floor when she wants to lay down. Mobility is a problem, as Autumn is unable to walk, crawl, or bear any of her own weight. We do have a lightweight manual wheelchair for use in the house, as well as a power chair, so she is able to have some freedom and independence. She has not yet had any issues with breathing or choking, which is the greatest cause for concern--and the common cause of death in persons with SMA. She continues with weekly clinical physical therapy, and is seen at her preschool by a physical therapist for periodic evaluations. Therapy focuses on reaching, balancing, range-of-motion exercises, and supported standing. In February 2007, she began taking Valproic Acid and Carnitine. Hopefully, these drugs will increase the usable amount of protein from the functional SMN2, and thus hopefully increase her muscle strength and stamina. For Autumn, we have not seen any decrease in the skills that she has obtained, and she continues to stay very healthy, which may be attributed to these medications.
Stay tuned for further information on new treatments genetic research, drug testing as they come available...