Clinical Guidance

SUCLA2-related mitochondrial DNA depletion syndrome, encephalomyopathic form with methylmalonic aciduria (SUCLA2-related mtDNA depletion syndrome) is characterized by onset of the following features in infancy: developmental delay, hypotonia, dystonia, muscular atrophy, sensorineural hearing impairment, growth failure, and feeding difficulties. Other less frequent features include choreoathetosis, muscle weakness, recurrent vomiting, ptosis, and kyphoscoliosis. The median survival is age 20 years; approximately 30% of affected individuals succumb during childhood. To date, 61individuals have been identified with biallelic pathogenic variants in SUCLA2, including 50 cases reviewed by , , , , , , , . The following description of the phenotypic features associated with this condition is based on these reports. Table 2. SUCLA2-Related Mitochondrial DNA Depletion Syndrome, Encephalomyopathic Form with Methylmalonic Aciduria: Frequency of Select Features Feature | % of Persons w/Feature Development

Diagnostic Criteria

No consensus clinical diagnostic criteria for SUCLA2-related mitochondrial DNA depletion syndrome, encephalomyopathic form with methylmalonic aciduria (SUCLA2-related mtDNA depletion syndrome) have been published.

Suggestive Findings

SUCLA2-related mtDNA depletion syndrome typically manifests during early infancy and should be suspected in a proband with a combination of the following clinical, brain MRI, and supportive laboratory findings and family history.

Clinical findings

Management Guidelines

No clinical practice guidelines for SUCLA2-related mitochondrial DNA depletion syndrome, encephalomyopathic form with methylmalonic aciduria (SUCLA2-related mtDNA depletion syndrome) have been published. Evaluations Following Initial Diagnosis To establish the extent of disease and needs in an individual diagnosed with SUCLA2-related mtDNA depletion syndrome, the evaluations summarized (if not performed as part of the evaluation that led to the diagnosis) are recommended. Table 4. SUCLA2-Related Mitochondrial DNA Depletion Syndrome, Encephalomyopathic Form with Methylmalonic Aciduria: Recommended Evaluations Following Initial Diagnosis

Surveillance Guidelines

To monitor existing manifestations, the individual's response to supportive care, and the emergence of new manifestations, the evaluations summarized in are recommended. Table 6. SUCLA2-Related Mitochondrial DNA Depletion Syndrome, Encephalomyopathic Form with Methylmalonic Aciduria: Recommended Surveillance