Effective disease management depends on early and accurate diagnosis of XLMTM

X-linked myotubular myopathy (XLMTM) diagnosis versus other neuromuscular disorders

Clinical suspicion of XLMTM can be challenging due to similarities with other congenital myopathies and neuromuscular disorders.1 Recognizing key clinical features of XLMTM and early genetic testing can accelerate diagnosis.

Unlike other neuromuscular disorders such as spinal muscular atrophy (SMA Type 1) in which symptoms can manifest any time from birth to 6 months, most patients with XLMTM present at birth with profound hypotonia and respiratory insufficiency.1-4

Suspicion of XLMTM may be based on family history and clinical findings

In addition to profound hypotonia and respiratory insufficiency at birth, these combined common features can assist in the differential diagnosis process1:

  • Family history of XLMTM
  • Facial weakness
  • Dolichocephaly (length and head circumference greater than 90th percentile)
  • Ophthalmoparesis, often associated with ptosis
  • Long fingers and toes
  • Bulbar weakness leading to insufficient sucking and swallowing
  • Areflexia (abnormal or absent reflexes)
  • Decreased fetal movement and polyhydramnios during gestation


1. North KN, et al. Neuromuscul Disord. 2014;24(2):97-116. 2. Beggs AH, et al. Muscle Nerve. 2018;57(4):550-560. 3. Graham RJ, et al. Arch Dis Child. 2020;105(4):332-338. 4. Arnold WD, et al. Muscle Nerve. 2015;51(2):157-167.


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