Question 1

What is combined oxidative phosphorylation defect type 21?

Accepted Answer

Combined oxidative phosphorylation defect type 21 is a very rare mitochondrial condition that primarily affects energy production in cells. It results from pathogenic variants in the TARS2 gene, which plays an essential role in mitochondrial protein synthesis. Affected individuals typically present in infancy with symptoms such as hypotonia, developmental delay, and central nervous system anomalies. This condition is considered very rare, affecting fewer than 1 in 1,000,000 individuals.

Question 2

What are the symptoms of combined oxidative phosphorylation defect type 21?

Accepted Answer

The clinical presentation includes a range of neurological and developmental challenges. Characteristic findings include axial hypotonia, limb hypertonia, and global developmental delay, alongside seizures and cerebral atrophy. Magnetic resonance imaging often reveals corpus callosum hypoplasia and lesions in areas such as the globus pallidus, reflecting the central nervous system involvement. Other common features include increased cerebral lipofuscin, reduced eye contact, hyperprolinemia, hyperalaninemia, and an elevated concentration of circulating lactate. Not all individuals experience every feature, and severity varies considerably.

Question 3

What causes combined oxidative phosphorylation defect type 21?

Accepted Answer

The condition is caused by pathogenic variants in the TARS2 gene, which encodes a mitochondrial threonyl-tRNA synthetase that is critical for proper mitochondrial protein synthesis and energy production. Disruption of this protein leads to multiple deficiencies in mitochondrial respiratory chain complexes, particularly affecting muscle tissue. Inheritance is autosomal recessive, meaning that an affected individual has inherited two copies of the altered gene, one from each parent. This condition is more common when parents share a common ancestor, as this increases the likelihood that both carry the same rare genetic variant. Genetic counseling is recommended to help families understand these risks and implications for future family planning. Associated genes include TARS2.

Question 4

How is combined oxidative phosphorylation defect type 21 inherited?

Accepted Answer

combined oxidative phosphorylation defect type 21 follows an autosomal recessive inheritance pattern. This means a child must inherit a copy of the altered gene from both parents to develop the condition. Parents who each carry one copy typically do not show symptoms.

Question 5

How rare is combined oxidative phosphorylation defect type 21?

Accepted Answer

combined oxidative phosphorylation defect type 21 is classified as very rare. The estimated prevalence is approximately <1 in 1,000,000. Because rare disease data can be limited, actual numbers may differ from published estimates.

Question 6

How is combined oxidative phosphorylation defect type 21 diagnosed?

Accepted Answer

Diagnosis of combined oxidative phosphorylation defect type 21 is confirmed through molecular genetic testing that identifies pathogenic variants in the TARS2 gene. In addition to genetic confirmation, clinical evaluation including assessment of developmental history, neurological examination, and neuroimaging studies such as magnetic resonance imaging play essential roles. Biochemical findings like elevated lactate levels further support the diagnosis, distinguishing this condition from others with overlapping clinical features. Because many of these features can be seen in other conditions, genetic testing remains the definitive method of diagnosis.

Question 7

Are there treatments for combined oxidative phosphorylation defect type 21?

Accepted Answer

Currently, management focuses on supportive care and symptom management, as there are no treatments specifically approved for combined oxidative phosphorylation defect type 21. Therapy is tailored to the individual and typically involves a multidisciplinary care team to address developmental, neurological, and metabolic challenges. Supportive interventions may include physical therapy, occupational therapy, and other measures aimed at improving quality of life. Genetic counseling is also recommended to help families navigate the implications of the autosomal recessive inheritance pattern and plan for future pregnancies. Patients should discuss treatment options with their healthcare team to determine the best approach for their situation.

Question 8

What are the potential complications of combined oxidative phosphorylation defect type 21?

Accepted Answer

Individuals with combined oxidative phosphorylation defect type 21 may face various complications due to their neurological and developmental challenges. These can include seizures, significant delays in reaching developmental milestones, and issues with muscle tone, such as hypotonia and hypertonia. Additionally, brain imaging may show abnormalities like corpus callosum hypoplasia, which can affect overall brain function.

Question 9

How does combined oxidative phosphorylation defect type 21 affect daily life for patients and families?

Accepted Answer

Living with combined oxidative phosphorylation defect type 21 can be challenging for both patients and their families. Daily life may involve regular therapy sessions, such as physical and occupational therapy, to help manage developmental delays and improve quality of life. Families may also need to adapt their routines to accommodate medical appointments and supportive care needs.

Question 10

What is the prognosis for someone with combined oxidative phosphorylation defect type 21?

Accepted Answer

The prognosis for combined oxidative phosphorylation defect type 21 varies widely among individuals. Some may experience significant challenges, while others might have periods of stability and improved quality of life with appropriate care. Advances in supportive treatments have led to better outcomes for some patients, but the disease course can still include motor difficulties as they grow older.

Question 11

What specialists should families consult for combined oxidative phosphorylation defect type 21?

Accepted Answer

Families dealing with combined oxidative phosphorylation defect type 21 should consider consulting a multidisciplinary care team. This team may include genetic counselors, neurologists, and developmental specialists who can provide comprehensive care and support. Working with specialists can help families navigate the complexities of the condition and access appropriate therapies and resources.

Organ System	Phenotype Count	Example Features
Brain and nerves	4	Brain shrinkage (cerebral atrophy), Seizure, Global developmental delay

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combined oxidative phosphorylation defect type 21

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Prognosis

Research Landscape

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Questions for Your Care Team

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Explore clinical features

combined oxidative phosphorylation defect type 21

Overview

Clinical Presentation

Genetic Landscape

Diagnosis

Prognosis

Research Landscape

Recent Publications

Medical References

External Resources

OMIM

Orphanet

GARD

Related Diseases

Questions for Your Care Team

Questions for Your Care Team

FAQ

Frequently Asked Questions

What is combined oxidative phosphorylation defect type 21?

What are the symptoms of combined oxidative phosphorylation defect type 21?

What causes combined oxidative phosphorylation defect type 21?

How is combined oxidative phosphorylation defect type 21 inherited?

How rare is combined oxidative phosphorylation defect type 21?

How is combined oxidative phosphorylation defect type 21 diagnosed?

Are there treatments for combined oxidative phosphorylation defect type 21?

What are the potential complications of combined oxidative phosphorylation defect type 21?

How does combined oxidative phosphorylation defect type 21 affect daily life for patients and families?

What is the prognosis for someone with combined oxidative phosphorylation defect type 21?

What specialists should families consult for combined oxidative phosphorylation defect type 21?

Explore clinical features