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Genetics

Behr Syndrome is an autosomal recessive disorder, which arises from the inheritance of defective genes. Often both genes, one inherited from the mother and one inherited from the father, need to be defective in order for the child to have this disorder. Although this is a recessive disorder, symptoms can be experienced in individuals with only one defective gene. Cases of Behr Syndrome with heterozygous individuals for the mutated gene are extremely rare. Generally, individuals with a single mutated gene will be unaffected and will not experience any symptoms. Behr Syndrome has been attributed to mutations in the OPA1, OPA3, or C12ORF65 genes. OPA1 and OP3 are genes targeted for the mitochondria and are involved in determining the shape and structure of the mitochondria. But the exact function of the two genes remains unknown. It is believed that there are other genes involved in Behr Syndome, but they remain unknown. The mutated gene is found on an autosomal chromosome, meaning that the mutations can be found on any of the chromosomes aside from the sex chromosomes. A common clinical feature of Behr Syndrome is infantile optic atrophy. The OPA1, OPA3, and C12ORF65 have been known to cause optic atrophy and movement complications associated with optic atrophy.

Research performed by Kelffner et al. found that there may be another gene associated with Behr Syndrome. It has been seen that mitochondrial dysfunction is a key factor in Behr Syndrome. This is caused by mutations in the C19ORF12 gene, which is targeted for the mitochondrial membrane. The C19ORF12 gene is highly prevalent in brain and blood cells and is thought to play a role in differentiation of adipocytes. But the exact function of C19ORF12 remains unknown. It has also been linked to neurodegeneration with brain iron accumulation (NBIA), which is a disease that shares many of the same symptoms as Behr Syndrome.

Clinical Features

Behr Syndrome has a spectrum of complications, which occurs in both sexes. One of the most common symptoms of Behr Syndrome is optic atrophy, which is also the earliest symptom to arise in patients. This deterioration of the optic nerve results in a range of visual impairment that progress on to adulthood. Other symptoms of Behr Syndrome include ataxia, myoclonic epilepsy, intellectual disability, bladder dysfunction, nystagmus, spasticity, and pyramidal tracts. Nystagmus is a condition involving involuntary rapid eye movements. These symptoms are not an exhaustive list, but rather a small compilation of common symptoms found in patients suffering from Behr Syndrome. Symptoms will often appear in early childhood and progress throughout the patient’s lifetime. Many patients suffering from Behr Syndrome will lose the ability to walk long distances or the ability to walk altogether.

There are no available treatments for Behr Syndrome. Currently, patients with Behr Syndrome are treated specifically for their symptoms.