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Spinal muscular atrophy–type I
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  1. M K M Hardart,
  2. R D Truog
  1. Department of Anesthesia, Children’s Hospital, Harvard Medical School, Boston, MA, USA
  1. Correspondence to:
    Dr M K M Hardart, Department of Anesthesia, Farley 517/MICU office, 300 Longwood Avenue, Boston, MA 02115, USA;
    katiemoyn{at}aol.com

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The challenge of defining a child’s best interests

Spinal muscular atrophy–type I or Werdnig-Hoffman disease is an autosomal recessive disorder of childhood that causes profound weakness and death from respiratory failure, typically by the age of 2 years in the absence of mechanical ventilation.1,2 Management of this condition is highly variable—while some patients and their families are not offered any form of respiratory support, patients in other settings are routinely treated with the full spectrum of respiratory assistance and supportive care.3 Unless this striking variability in practice can be justified on the basis of factors related to individual differences between patients, it must represent either a failure to appreciate key factors about the disease or the influence of professional values and norms on the decision making process.

THE UNDERLYING PROBLEM

The spinal muscular atrophies (SMA) are a spectrum of inherited neuromuscular diseases caused by the degeneration of anterior horn cells. The SMAs are categorised into stages based on age of onset, with type I defined by evidence of weakness before 6 months of age.4 While patients with this disorder have normal intellect, they generally have rapid neuromuscular deterioration and suffer a respiratory death in the first two years of life.1,2 Those patients with other forms of SMA have later onset of symptoms, experience a slower progression of muscle weakness, and respiratory symptoms may not arise until the teenage or adult years. The physician must be careful, however, when using this classification scheme to prognosticate for a given child. Several studies have cited many examples of children with onset of symptoms before age 6 months who have not developed respiratory failure for years.2,4–6 While 93% of all SMA patients are lacking a “survival motor neurone gene”,7–9 the genetic basis for phenotypic variability remains …

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