Summary about Disease
Kugelberg-Welander disease, also known as spinal muscular atrophy type 3 (SMA3), is a genetic neuromuscular disorder characterized by progressive muscle weakness. It is a milder form of spinal muscular atrophy compared to SMA1 and SMA2. The disease primarily affects the muscles closest to the trunk of the body (proximal muscles), such as those in the shoulders, hips, and thighs. This weakness leads to difficulties with movements like walking, running, and climbing stairs. The age of onset and severity of symptoms vary, influencing the individual's functional abilities and life expectancy.
Symptoms
Symptoms of Kugelberg-Welander disease include:
Muscle weakness: Primarily in the legs and arms, affecting proximal muscles more than distal muscles.
Fatigue: Feeling tired and weak after minimal exertion.
Tremors: Fine trembling of the fingers.
Muscle cramps: Involuntary muscle contractions that can be painful.
Difficulty with motor skills: Problems with walking, running, climbing stairs, or getting up from a seated position.
Scoliosis: Curvature of the spine, which may develop over time.
Respiratory Issues: Though less common and severe than in other types of SMA, respiratory weakness can occur as the disease progresses.
Causes
Kugelberg-Welander disease is caused by a genetic defect in the SMN1 (survival motor neuron 1) gene located on chromosome 5. This gene produces a protein essential for the survival of motor neurons, which control muscle movement. In most cases (about 95%), individuals with SMA have a deletion or mutation in both copies of the *SMN1* gene. A backup gene, *SMN2*, produces a small amount of the SMN protein. The number of *SMN2* copies an individual has can influence the severity of the disease; more copies generally correlate with a milder presentation. The disease is inherited in an autosomal recessive pattern, meaning that both parents must be carriers of the defective gene for their child to be affected.
Medicine Used
Several medications are used to treat SMA, including Kugelberg-Welander disease (SMA3). These treatments aim to increase the amount of functional SMN protein.
Nusinersen (Spinraza): An antisense oligonucleotide that alters SMN2 splicing to produce more functional SMN protein. Administered via intrathecal injection (into the spinal fluid).
Risdiplam (Evrysdi): An oral SMN2 splicing modifier, meaning it helps the *SMN2* gene create more of the missing SMN protein.
Onasemnogene abeparvovec-xioi (Zolgensma): A gene therapy that delivers a functional copy of the SMN1 gene into the patient's cells. Given as a one-time intravenous infusion.
Supportive Therapies: Physical therapy, occupational therapy, respiratory support (if needed), nutritional support, and orthopedic management (for scoliosis) are also important aspects of care.
Is Communicable
Kugelberg-Welander disease (SMA3) is not communicable. It is a genetic disorder and cannot be spread from person to person through any form of contact.
Precautions
Since Kugelberg-Welander disease is genetic, there are no preventative precautions that can be taken by an individual to avoid developing it once they are born. Precautions and management strategies focus on:
Genetic Counseling: For families with a history of SMA, genetic counseling can help assess the risk of having a child with the condition and provide information about available testing options.
Managing Symptoms: Regular physical therapy, occupational therapy, and respiratory support (if needed) can help manage symptoms and improve quality of life.
Preventing Complications: Monitoring for scoliosis, respiratory difficulties, and other potential complications, and addressing them promptly.
How long does an outbreak last?
Kugelberg-Welander disease is not an outbreak-related illness. It is a chronic genetic condition that is present from birth, though the onset of symptoms can vary. The symptoms are progressive, meaning they worsen over time. There is no "outbreak" period as with infectious diseases.
Timeline of Symptoms
The timeline of symptoms in Kugelberg-Welander disease (SMA3) is variable, but it generally follows this pattern:
Onset: Typically occurs after infancy, usually between 18 months and adulthood.
Early Symptoms: May include subtle weakness, difficulty with activities like running, jumping, or climbing stairs, and frequent falls.
Progression: Muscle weakness progresses over time, leading to increasing difficulty with ambulation and other motor skills. Scoliosis may develop.
Later Stages: Some individuals may eventually require assistive devices like wheelchairs for mobility. Respiratory weakness can become more pronounced, though it is generally less severe than in other forms of SMA.
Important Considerations
Variability: The severity and progression of Kugelberg-Welander disease can vary significantly among individuals.
Multidisciplinary Care: Management requires a multidisciplinary team, including neurologists, pulmonologists, physical therapists, occupational therapists, orthopedists, and genetic counselors.
New Therapies: Advances in treatment have dramatically improved the outlook for individuals with SMA. Early diagnosis and intervention are crucial to maximize the benefits of these therapies.
Quality of Life: Supportive care and adaptive strategies are essential to maintain quality of life, independence, and participation in activities.
Emotional Support: Both patients and families benefit from psychological support and counseling to cope with the challenges of living with a chronic neuromuscular disorder.