REFSUM DISEASE

Phytanic alpha oxidase [Ref: Nelson I7/e p2077; Chatterjee Shinde Biochemistry 6/e p349]

Refsum’s disease is a rare genetic disorder due to deficiency of phytanate alpha oxidase.

Phytanic acid is unable to be converted into pristanic acid leading to its accumulation in blood CSF and brain tissue. The symptoms are mainly neurological, and the treatment involves dietary restriction to halt disease progression.

Refsum’s disease is a rare neurologic disorder due to a metabolic defect that results in the accumulation of phytanic acid, which is found in dairy products and ruminant fat and meat. Phytanic acid is thought to have pathological effects on membrane function, protein prenylation, and gene expression.

Rare Hereditary Neuropathies

B) Hereditary Ataxias With Neuropathy 

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Systemic conditions associated with enlarged corneal nervesare MEN Type 2b, Refsum syndrome and neurofibromatosis.

Local ocular disease with this sign includes keratoconus, keratitis (characteristically in acanthamoeba keratitis), Fuch’s endothelial dystrophy, trauma and congenital glaucoma.

Band shaped keratopathy is a degenerative condition seen in the cornea. It is common in chronic uveitis, also in children suffering from Still’s disease, hyperparathyroidism, vit D poisoning, sarcoidosis. It begins as a whitish band which appear in the interpalpebral area and progress to form a continuous band across the cornea interspersed with round holes or cleaves in the band.

Ref: Parson’s diseases of eye, 21st edn-page:192

Some forms of retinitis pigmentosa occur in association with rare, hereditary systemic diseases like olivopontocerebellar degeneration, Bassen-Kornzweig disease (abetalipoproteinemia), Kearns-Sayre syndrome, Refsum’s disease, and neuropathy, ataxia, and retinitis pigmentosa (NARP) syndrome.

• Chronic treatment with chloroquine, hydroxychloroquine, and phenothiazines (especially thioridazine) can produce visual loss from a toxic retinopathy that resembles retinitis pigmentosa.
• Hallervorden-Spatz disease or neurodegeneration with brain iron accumulation 1 (NBIA1) or pantothenate kinase-associated neurodegeneration (PKAN), is characterized by extrapyramidal and cognitive abnormalities, dysarthria, dysphagia, and ocular abnormalities (eg, gaze palsies, optic atrophy).

Ref: Horton J.C. (2012). Chapter 28. Disorders of the Eye. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds), Harrison’s Principles of Internal Medicine, 18e.

D i.e. Phytanic alpha oxidase

Refsum’s disease is a rare autosomal recessive disorder caused by deficiency of phytanic a oxides (Nelson) / a‑hydroxylase (Lippincot) / Phytanoyl CoA hydroxylase (Lehninger) results in accumulation of phytanic acid due to its decreased a – oxidation (i.e. hydroxnlation at a carbon by fatty acid a hydroxylase)

Ans. is ‘b’ i.e., Refsum’s syndrome

Refsum disease is characterized by ataxia, ichthyosis, cardiomyopathy, retinitis pigmentosa and absent tendon reflexes.

B. i.e. Refsum’s disease

Icthyosis is seen in Hypothyroidism, AIDS, Refsum disease and LymphomaQ. (Mn-“HARLY i.e. name of motor cycle Harly Davidson).

            B i.e. Hallervordm spatz syndrome

A. i.e. Phytanic acid oxidase

Ans. Lowe’s syndrome

Ans. Hallervorden Spatz Syndrome

Ans. is ‘a’ i.e., Retinitis pigmentosa

Associations of retinitis pigmentosa

Ocular associations : These include myopia, primary open angle glaucoma, microphthalmos, conical cornea and posterior subcapsular cataract.

Systemic associations : These are in the form of following syndromes :-

i) Laurence-Moon-Biedl syndrome : It is characterised by retinitis pigmentosa, obesity, hypogenitalism, polydactyly and mental deficiency.

ii) Cockayne’s syndrome : It comprises retinitis pigmentosa, progressive infantile deafness, dwarfism, mental retardation, nystagmus and ataxia.

iii) Refsum’s syndrome : It is characterized by retinitis pigmentosa, peripheral neuropathy and cerebellar ataxia.

iv) Usher’s syndrome : It includes retinitis pigmentosa and labyrinthine deafness.

v) Hallgren’s syndrome : It comprises retinitis pigmentosa, vestibulo-cerebellar ataxia, congenital deafness and mental deficiency.