All of the following are true about Frederich's ataxia except
*Friedreich's ataxia is most common; autosomal recessive, onset before age 25; ataxia with areflexia, upgoing toes, vibration and position sense deficits, cardiomyopathy, hammer toes, scoliosis; linked to expanded trinucleotide repeat in the intron of gene encoding frataxin; a second form is associated with genetically determined vitamin E deficiency syndrome. Common dominantly inherited ataxias are spinocerebellar ataxia (SCA)1 (olivopontocerebellar atrophy; "ataxin-1" gene) (Fig. 184-1), SCA2 (ataxin-2; pts from Cuba and India) and SCA3 (Machado-Joseph disease); all may manifest as ataxia with brainstem and/or extrapyramidal signs; SCA3 may also have dystonia and amyotrophy; genes for each disorder contain unstable trinucleotide repeats in coding region. Symptoms may include the following: 91% of people develop hea problems such as cardiomegaly (up to dilated cardiomyopathy), symmetrical hyperophy, hea murmurs, atrial fibrillation, tachycardia (fast hea rate), hyperophic cardiomyopathy) and conduction defects Cerebellar: nystagmus, fast saccadic eye movements, dysmetria, loss of coordination (truncal ataxia and Stomping gait) Vision impairment Hearing impairment Slurred speech Abnormal curvature of the spine Dorsal column: Loss of vibratory sensation and proprioceptive sensation occurs About 20% of people have trouble metabolizing carbohydrates and 10% develop diabetes mellitus Lower motor neuron lesion: absent deep tendon reflexes Pyramidal: extensor plantar responses, and distal weakness Muscle weakness in the arms and legs High plantar arches Ref Harrison20th edition pg 2765
Autosomal recessive
Spinal cord, dorsal root ganglion cell are primarily involved
Weakness in lower limbs
Plantar flexor response
C.N.S