Fast Five Quiz: Can You Recognize Kugelberg Welander Spinal Muscular Atrophy?

Stephen L. Nelson, Jr, MD, PhD


December 06, 2018

Kugelberg Welander SMA is SMA type III; this type is also referred to as chronic juvenile-onset SMA, Wohlfart-Kugelberg-Welander syndrome, or mild SMA. SMA types I through IV are classified based on age of symptom onset and prognosis. Sign and symptom onset of SMA type III occurs in patients older than 18 months, typically between ages 2 and 12 years.

SMA type I (acute infantile-onset or Werdnig-Hoffmann disease): This is the most common and severe form of SMA, with the highest mortality rate (95% mortality by age 18 months). Symptoms are present at birth, or appear by age 6 months.

SMA type II (chronic infantile-onset or Dubowitz disease): Severe symptom onset occurs between ages 7 months and 18 months. The average lifespan of patients with SMA type II ranges from age 2 years to the third decade of life.

SMA type IV (adult-onset): Although patients with SMA type IV may develop symptoms as early as age 10 years, disease onset typically occurs in the fourth decade of life, usually in the mid-30s. SMA type IV is the mildest form of SMA and has the best prognosis of all SMA types.

For more on SMA types, read here.


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