Behr syndrome: a clinicopathologic report

Familial optic atrophy with white matter changes

We report two brothers who suffer from infantile onset optic atrophy and blindness. MRI of the brain demonstrated periventricular white matter changes in both children. Neurological and developmental examination are normal. Extensive laboratory investigations rule out metabolic disorders that can be associated with optic atrophy. No mutations associated with Leber hereditary optic neuropathy (LHON) were found and sequencing of the mitochondrially encoded complex 1 subunits was normal. We suggest that this family represents either an atypical variant of LHON with a yet undescribed mtDNA mutation or a new syndrome.

Hereditary ataxias

There are many causes of hereditary ataxia. These can be grouped into categories of autosomal recessive, autosomal dominant, and X-linked. Molecularly, many of them are due to trinucleotide repeat expansions. In Friedreich ataxia, the trinucleotide repeat expansions lead to a "loss of function." In the dominant ataxias, the expanded repeats lead to a "gain of function," most likely through accumulation of intranuclear (and less commonly cytoplasmic) polyglutamine inclusions. Channelopathies can also lead to ataxia, especially episodic ataxia. Although phenotypic characteristics are an aid to the clinician, a definitive diagnosis is usually made only through genotypic or molecular studies. Genetic counseling is necessary for the testing of symptomatic and asymptomatic individuals. No effective treatment is yet available for most ataxic syndromes, except for ataxia with isolated vitamin E deficiency and the episodic ataxias.

Type IV 3-methylglutaconic (3-MGC) aciduria: a new case presenting with hepatic dysfunction

We describe a new patient with type IV 3-methylglutaconic aciduria who presented with a clinical picture simulating a primary hepatic disorder subsequently followed with progressive neurologic impairment and an magnetic resonance imaging picture of Leigh syndrome.

MRI abnormalities in Behr syndrome

The etiology of Behr syndrome remains uncertain. A 6-year-old girl with a progressive syndrome of optic atrophy, ataxia, myoclonic epilepsy, urinary incontinence, and pyramidal tract degeneration suggestive of Behr syndrome is described. Diffuse, symmetric white matter abnormalities were demonstrated by magnetic resonance imaging suggesting that Behr syndrome may represent a disorder of white matter associated with an unknown biochemical abnormality.

Multiple syndromes of 3-methylglutaconic aciduria

The most common clinical syndromes associated with 3-methylglutaconic aciduria are presented. In some patients these syndromes are multisystemic, progressive disorders of unknown etiology. Tissues deriving significant energy through oxidative metabolism (notably brain and cardiac muscle) are most often affected and in some the primary defect may reside within the mitochondrial respiratory chain. Although increasing biochemical evidence suggests that 3-methylglutaconic aciduria may correlate with deranged mitochondrial energy metabolism, the biochemical origin of 3-methylglutaconic acid and the significance of its increased excretion remain unknown. This review describes these syndromes and illustrates the necessity of urinary organic acid analysis to assist in the differential diagnosis.

Optic nerve hypoplasia associated with pupillary light-near dissociation, spastic paraparesis and other non-ocular anomalies

We report a case of bilateral optic nerve hypoplasia in a patient with pupillary light-near dissociation, spastic paraparesis with deep hyperreflexia, mild distal hypotrophy especially of lower limbs, bilateral pes cavus and signs of motor peripheral neuropathy. Other associated signs were rhinolalia, hypotrophy and fasciculations of the tongue and cardiomyopathy. We differentiate the condition from a number of hereditary ataxias and paraplegias. The clinical features of Strümpell-Lorrain spastic paraplegia and amyotrophic lateral sclerosis seem to resemble most closely that of our patient.

Behr's syndrome. A family exhibiting pseudodominant inheritance

A family with the clinical features of Behr's syndrome is described that exhibited probable pseudodominant inheritance. The salient clinical manifestations consisted of mental retardation and dementia, optic atrophy, cerebellar ataxia, pyramidal signs and peripheral neuropathy. Nerve biopsy from the index case showed a chronic neuropathy with axonal degeneration and regeneration. A muscle biopsy from the same patient demonstrated multiple inclusions composed of spiral cylindrical structures possibly derived from the sarcoplasmic reticulum, and less obtrusive accumulations of mitochondria, some of which contained paracrystalline inclusions.

A tentative classification of recessively inherited ataxias

We present a working classification of recessively inherited ataxic syndromes based on the use of simple tools available to every clinician: a good history (particularly pinpointing the age of onset) and a good neurological examination (simplified to the verification of the presence of ataxia, deep tendon reflexes in the knee, optic nerve, retinal and/or 8th nerve signs). In the three groups of disorders (non progressive, intermittent or progressive) patients can be hyper/normo reflexic, or they can be hypo/areflexic. Six principal types of progressive ataxic disorders are further delineated by the age of onset. Sub-types depend on the presence of absence of eye and ear signs, whereas eponymic or regional denominations are used only for simplicity while awaiting exact delineation of the biochemical defects.