Table 2.

Clinical Manifestations of FBXL4-Related Mitochondrial DNA Depletion Syndrome

Clinical ManifestationFrequency
Neurologic 50/50 (100%)
  • Developmental delay
  • Hypotonia
  • Seizures
  • Movement disorders 1
  • Ataxia
  • Autonomic dysfunction
  • Stroke-like episodes
  • 45/45 (100%)
  • 39/42 (93%)
  • 14/42 (33%)
  • 5/17 (29%)
  • 4/15 (27%)
  • 3/12 (25%)
  • 1/32 (3%)
Growth
  • Failure to thrive
  • IUGR
  • Short stature
  • Microcephaly (congenital & acquired)
  • 25/33 (76%)
  • 18/31 (58%)
  • 17/31 (55%)
  • 14/36 (39%)
Gastrointestinal
  • Feeding difficulties
  • Hepatopathy
  • 27/31 (87%)
  • 8/24 (33%)
Cardiac 20/37 (54%)
  • Cardiomyopathy
  • Congenital heart malformations
  • Arrhythmia
  • Pulmonary hypertension
  • 10/37 (27%)
  • 7/37 (19%)
  • 6/41 (15%)
  • 4/37 (11%)
Ophthalmologic 20/30 (67%)
  • Cataract
  • Strabismus
  • Nystagmus
  • Optic atrophy
  • 5/30 (17%)
  • 5/31 (16%)
  • 6/30 (20%)
  • 3/30 (10%)
Other
  • Neutropenia
  • Hearing impairment
  • 8/43 (19%)
  • 4/33 (12%)

IUGR = intrauterine growth restriction, defined as birth weight <10th centile

1.

Movement disorders reported include dystonia, choreoathetosis, hyperkinetic movements, and tremors [Gai et al 2013, Barøy et al 2016, Pronicka et al 2016].

From: FBXL4-Related Encephalomyopathic Mitochondrial DNA Depletion Syndrome

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