Behr Early Onset Optic Atrophy Syndromes

Clinical Characteristics
Ocular Features: 

Optic atrophy is the earliest sign in Behr syndrome and may be evident in early childhood.  Nystagmus is a variable feature.  Acuity in the first decade is in the 20/70 to 20/100 range with little worsening in patients followed for a decade or more even though the disc pallor may increase with loss of papillary vasculature.  ERGs are normal but VEPs are usually abnormal.

Systemic Features: 

The nosology of infantile optic atrophy is unclear.   There is no doubt that some familial cases with likely autosomal recessive inheritance lacked (or were not tested for) urinary metabolites considered diagnostic for an optic atrophy disorder with 3-methylglutaconate aciduria (258501) and labeled methylglutaconic aciduria type III (and sometimes Costeff optic atrophy syndrome).  Excretion of 3-methylglutaric acid may also be increased.  But it is also possible that another form of infantile optic atrophy without aminoaciduria also exists.  Early onset (early childhood) optic atrophy, with later (second decade) spasticity, ataxia, extrapyramidal signs and cognitive defects to some degree are common to both.  Dementia, posterior column signs and peripheral neuropathy are more variable clinical signs.  Nerve biopsies and postmortem studies show widespread disease with evidence of chronic neuropathy, neuronal loss, and gliosis.  In Behr's report, the neurologic symptoms remained static after a period of progression.   Others have reported progression with the majority of patients severely handicapped by the third decade of life.

Genetics

Sibs born to consanguineous parents suggest autosomal recessive inheritance in both Behr syndrome with ataxia and in 3-methylglutaconic aciduria, type III.  The latter is most commonly found among Iraqi Jews and is the result of a mutation in the OPA3 gene (19q13.2-q13.3).  The genetic basis for simple Behr infantile optic atrophy is unclear and it is likely that multiple unique entities exist.  This disorder is allelic to an autosomal dominant disorder called Optic Atrophy 3 and Cataracts (165300) but the uniqueness of the latter entity is uncertain.

Treatment
Treatment Options: 

None known

References
Article Title: 

References

Felicio AC, Godeiro-Junior C, Alberto LG, Pinto AP, Sallum JM, Teive HG, Barsottini OG. Familial Behr syndrome-like phenotype with autosomal dominant inheritance. Parkinsonism Relat Disord. 2008;14(4):370-2

PubMedID: 17977780

Sheffer RN, Zlotogora J, Elpeleg ON, Raz J, Ben-Ezra D. Behr's syndrome and 3-methylglutaconic aciduria. Am J Ophthalmol. 1992 Oct 15;114(4):494-7

PubMedID: 1384336

Anikster Y, Kleta R, Shaag A, Gahl WA, Elpeleg O. Type III 3-methylglutaconic aciduria (optic atrophy plus syndrome, or Costeff optic atrophy syndrome): identification of the OPA3 gene and its founder mutation in Iraqi Jews. Am J Hum Genet. 2001 Dec;69(6):1218-24.

PubMedID: 11668429