Encephalopathy Due To Defective Mitochondrial And Peroxisomal Fission 2

Clinical Characteristics
Ocular Features: 

Visual impairment and optic atrophy are usually present.  Visual-evoked potentials may be negative or slowed severely.  Some degree of ophthalmoparesis is often present while frank external ophthalmoplegia can develop in the second year of life.  In one patient aged 7 years, MRI showed increased T2 signals in the optic radiation.

Systemic Features: 

Microcephaly becomes evident in the first year of life and seizures can appear in this period as well.  General developmental delays are present.  There may be evidence of Leigh-like basal ganglia disease.  Dysphagia may require the placement of a gastroscopy tube.  Truncal hypotonia can be so severe that sitting and head control are not possible.  However, there is often spasticity and hyperreflexia in the limbs.  EEG recordings show hypsarrhythmia.

Brain MRI may show increased T2 signaling in the global pallidus, thalamus, and the subthalamic nucleus.

Patients may never be able to sit or walk and usually do not develop speech.  


Homozygous or compound heterozygous truncating mutations in the MFF gene (mitochondrial fission factor) (2q36.3) is responsible for this condition.  Patients with EMPF2 may have abnormally elongated and tubular mitochondria and peroxisomes in fibroblasts.

Treatment Options: 

No treatment is available for the general disorder.  Gastrostomy tubes may be required to maintain adequate nutrition.  Airway hygiene is important.  Respiratory complications can be a factor in the early demise of children.

Article Title: 


Koch J, Feichtinger RG, Freisinger P, Pies M, Schrodl F, Iuso A, Sperl W, Mayr JA, Prokisch H, Haack TB. Disturbed mitochondrial and peroxisomal dynamics due to loss of MFF causes Leigh-like encephalopathy, optic atrophy and peripheral neuropathy. J Med Genet. 2016 Apr;53(4):270-8.

PubMedID: 26783368

Shamseldin HE, Alshammari M, Al-Sheddi T, Salih MA, Alkhalidi H, Kentab A, Repetto GM, Hashem M, Alkuraya FS. Genomic analysis of mitochondrial diseases in a consanguineous population reveals novel candidate disease genes. J Med Genet. 2012 Apr;49(4):234-41.

PubMedID: 22499341