drpkaur
Forum Guru
Topics: 195
Posts: 808
|
An infant come with seizures and hypotonia. he has a defect in oxidation of very long chain fatty acids? which organelle is not functioning?
a. nucleus
b. peroxisomes
c. mitochondrion
d. golgi
e. endoplasmic reticulum
what disease is it?
a. refsums disease
b. krabbes
c. von gierkes
d. zellweger
e. gauchers
|
| star1
Forum Guru
Topics: 93
Posts: 826
|
B peroxisome and disease is refsums disease
|
| blueocean
Forum Senior
Topics: 15
Posts: 195
|
the first answer is peroxizome but I guess the second is zelweger because it's match with clinical sequence; refsum usually begins in late childhood with degeneration of the retina (retinitis pigmentosa) ,anosmia,deafness, ataxia, peripheral neuropathy, ichthyosis and cardiac arrhythmias.
zelweger beginis in infancy and has a more symptoms:hypotonia, seizures, hyporeflexia, cataract, facial deformities with the
|
| icemaiden
Forum Elite
Topics: 9
Posts: 117
|
Peroxisome & zellweger. Refsum's is related to oxidation of phytanic acid----a branched chain fatty acid. But there is a doubt---why cant the organelle be mitochondria ,due to LCAD deficiency?
|
| blueocean
Forum Senior
Topics: 15
Posts: 195
|
Peroxisome Biogenesis Disorders - Zellweger syndrome (ZS), neonatal adrenoleukodystrophy (NALD), infantile Refsum disease (IRD) are really a single spectrum of disease, genetically and chemically almost indistinguishable; and particular diagnosis is as much as anything based on the degree of severity of the child's condition
|
| drpkaur
Forum Guru
Topics: 195
Posts: 808
|
correct answer is peroxisomes and Zellweger's syndrome-it's related with beta oxidation of very long chain fatty acids ...VLCFA undergo a preliminary beta oxidation in peroxisomes..the shortened fatty acids are then transferred to mitochondria for further oxidation..zellweger's syndrome(cerebrohepatorenal )is due to defect in peroxisomal biogenesis in all tissues and X-linked adrenoleukodystrophy is due to defect in peroxisomal activation of VLCFA..BOTH leading to accumulation of VLCFA in blood and tissues.
|
| icemaiden
Forum Elite
Topics: 9
Posts: 117
|
'k. thanks
|
| drpkaur
Forum Guru
Topics: 195
Posts: 808
|
let's come to Refsum's disease . Refsum's is related to alpha oxidation of phytanic acid----a branched chain fatty acid.
phytanic acid undergoes hydroxylation at alpha carbonby FA alpha -hydroxylase ...and refsum's disease is due to deficiency of this particular enzyme leading to accumulation of phytanic acid in blood n tissues causing neurologic symptoms.
|
| drpkaur
Forum Guru
Topics: 195
Posts: 808
|
REfsum's disease-
The onset of symptoms is typically in late childhood or adolescence, but may be as late as the fifth decade. The disease usually follows a progressive course, but acute and sub-acute presentations have been described. The cardinal neurological manifestations of the disease include a demyelinating neuropathy, pes cavus, cerebellar ataxia, sensorineural deafness, anosmia and cranial nerve involvement.7 There may be marked nerve hypertrophy. Nyctalopia and visual failure secondary to retinitis pigmentosa often precede the neurological symptoms. Most patients have gross constriction of the visual fields by the time they present.8 Cataracts and photophobia caused by impaired pupillary light responses are also described. Miosis may occur because of high lipid levels in the iris or as a consequence of a generalized dysautonomia. Cardiac involvement (conduction abnormalities and a cardiomyopathy) has resulted in premature death. Aminoaciduria secondary to reversible renal involvement is usually associated with extremely high phytanic acid levels. The skin is also affected, with rough scaly thickening over the extremities.9 Epiphyseal dysplasia results in syndactyly and a characteristic shortening of the fourth toe, which is diagnostically useful .
genetics of refsum's-
Classical Refsum's disease is one of a group of disorders of the peroxisome, an organelle that is found in most tissues (Table 1). Peroxisomal disorders are subdivided into two major categories.href="http://qjmed.oxfordjournals.org/cgi/content/full/94/8/403#R17">17 Phytanic acid levels can be raised in PBD disorders, as discussed above. The second category of peroxisomal disorders, which include classical Refsum's disease and X-linked adrenoleukodystrophy, differ in that they have a defect involving a single peroxisomal enzyme, and the peroxisomal structure is intact. The single enzyme deficient in classical Refsum's disease is phytanoyl-CoA hydroxylase. The gene (PAHX) for this enzyme is on chromosome 10, and both point mutations and deletions have been described in PAHX associated with Refsum's disease.18,href="http://qjmed.oxfordjournals.org/cgi/content/full/94/8/403#R20">20 Further evidence for this comes from a recent report of an 18-year old patient with psychomotor retardation and abnormally short metatarsals and metacarpals and elevated pipecolic acid levels.21 This patient was shown to have a homozygous deletion in the phytanoyl-CoA hydroxylase gene PAHX.
|
|
| |
| | | | | | | | | |
