Combined Oxidative Phosphorylation Deficiency 32

Clinical Characteristics
Ocular Features: 

Ocular signs are common but variable.  Patients may not make eye contact and sometimes have disconjugate eye movements.  Strabismus (usually exotropia) and nystagmus or often present.

Systemic Features: 

Six patients from 4 unrelated families of mixed ethnic backgrounds have been reported.  Infants within the first 4 to 6 months of life had evidence of developmental delay and neurodevelopmental regression.  Poor feeding and breathing difficulties are often noted in this period.  Other later signs are axial hypotonia, abnormal movements such as tremor, spasticity, hyperkinetic movements, dystonia with eventual regression of milestones.  Joint contractures and kyphoscoliosis may develop. 

Microcephaly was noted in several infants and brain imaging in all patients reveals abnormal T2- weighted signals in the brainstem and specifically in the basal ganglia.  Decreased activity in muscle mitochondrial respiratory complexes I, III, and IV has been documented.  Lactate may be increased in serum and the CSF.  Postmortem studies show brain vascular proliferation and gliosis in basal structures.


Homozygous or compound heterozygous mutations in MRPS34 (16p13.3) are the basis for this disorder.

Autosomal recessive
Treatment Options: 

No treatment has been reported.

Article Title: 

Biallelic Mutations in MRPS34 Lead to Instability of the Small Mitoribosomal Subunit and Leigh Syndrome

Lake NJ, Webb BD, Stroud DA, Richman TR, Ruzzenente B, Compton AG, Mountford HS, Pulman J, Zangarelli C, Rio M, Bodaert N, Assouline Z, Sherpa MD, Schadt EE, Houten SM, Byrnes J, McCormick EM, Zolkipli-Cunningham Z, Haude K, Zhang Z, Retterer K, Bai R, Calvo SE, Mootha VK, Christodoulou J, Rotig A, Filipovska A, Cristian I, Falk MJ, Metodiev MD, Thorburn DR. Biallelic Mutations in MRPS34 Lead to Instability of the Small Mitoribosomal Subunit and Leigh Syndrome. Am J Hum Genet. 2017 Aug 3;101(2):239-254.

PubMed ID: 
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