Familial Vitamin B&lt;sub&gt;12&lt;/sub&gt; Malabsorption

Imerslund, Olga; Bjørnstad, Per G.

doi:10.1159/000208104

Cited by 40 publications

(12 citation statements)

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“…(2) Failure to form methyl-B 12 , a cofactor required by iV 6 -methyltetraliydrofolate-homocysteine methyltransferase may also be responsible. This failure may be the result of either B 12 deficiency, occurring, for example, in familial gastrointestinal malabsorption of B 12 [15,17], or the result of impaired cellular uptake or metabolism of B 12 (deficiency in reaction pathway 16, Fig. 1) [23,33,34,36].…”

Section: Introductionmentioning

confidence: 99%

Homocystinuria: Studies in Tissue Culture

1973

Pediatr Res

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ExtractCystathionine synthase activities are reported for extracts of fibroblasts grown from 39 control subjects, 47 homocystinuric individuals, and 10 parents of cystathionine synthase-deficient patients. Among the group with homocystinuria, fibroblast extracts from 38 had specific activities of cystathionine synthase below the control range. A number of considerations indicate that these 38 patients excrete homocystine because of cystathionine synthase deficiency. Fibroblasts from nine patients with homocystinuria had specific activities of cystathionine synthase within the control range. This group of nine was shown to be comprised of two individuals with cystathionine synthase deficiency, three with deficient activity of methylenetetrahydrofolate reductase, three with deficient activity of iV 5 -methyltetrahydrofolate-homocysteine methyltransferase, and one in whom homocystine excretion found by others in earlier studies could not be confirmed during the present investigation. The specific activities in fibroblasts of parents of cystathionine synthase deficient patients in most cases fall near the low end of the control range.An assay of increased sensitivity was used to measure the cystathionine synthase activities in extracts of fibroblasts from cystathionine synthase-deficient patients at several concentrations of added pyridoxal phosphate. Of 25 cystathionine synthase-deficient patients judged to be clinically responsive to pyridoxine treatment, 24 had detectable cystathionine synthase activities in fibroblast extracts when the assays were performed without added pyridoxal phosphate. These activities ranged from approximately 0.1 % to 10% of the mean control value, and generally were stimulated no more by the addition of pyridoxal phosphate than were extracts from normal cells. Of 10 cystathionine synthase-deficient patients judged not to be responsive to pyridoxine, 9 had no cystathionine synthase activity in fibroblast extracts detected by the method employed. The cystathionine synthase in the cell extracts of the single nonresponsive patient with significant activity was stimulated much more by in vitro addition of pyridoxal phosphate than was control cystathionine synthase.Genetic heterogeneity in cystathionine synthase-deficient patients and some of the genetic implications of the demonstrated a 2 /32 subunit structure of mammalian cystathionine synthase are discussed. Speculation

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Section: Introductionmentioning

confidence: 99%

Homocystinuria: Studies in Tissue Culture

1973

Pediatr Res

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“…vitamin B,2 they were in good condition and in haematological remission. Their complete case histories and the laboratory findings are described in the earlier papers (4,5). In the present paper they have the same designation as before with roman numbers.…”

Section: Methodsmentioning

confidence: 92%

“…The absorption of radioactive vitamin B12 has been measured by the method of Schilling (7) as described in our previous communication (5).…”

Section: Methodsmentioning

confidence: 99%

“…Recently we have described 10 cases of a familial and appar ently congenital malabsorption of vitamin B12 (4,5) in which none of hitherto known causes of vitamin B12 malabsorption could be demonstrated. It was evident that the defect in these patients was located at the level of the small intestine, and was due to an inter ference with the transport of vitamin B12 across the intestinal wall.…”

Section: By Pal Bjornstad and Olga Imerslundmentioning

confidence: 99%

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Studies of Patients with Familial Vitamin B<sub>12 </sub> Malabsorption

Bjørnstad¹,

Imerslund²

1963

Acta Haematol

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“…In 1963, Imerslund described a similar disorder called idiopathic chronic megaloblastic anemia in children [ 147 ]. The disease was first diagnosed in Finland and Norway where the estimated prevalence is 1:200,000.…”

Section: Imerslund-gr ä Sbeck Syndrome (Igs) or Juvenile Megaloblastimentioning

confidence: 99%

Genetic defects in folate and cobalamin pathways affecting the brain

Kirsch

Herrmann

Obeid

2012

Clinical Chemistry and Laboratory Medicine (CCLM)

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Folate and cobalamin are necessary for early brain development and function. Deficiency of folate or cobalamin during pregnancy can cause severe malformation in the central nervous system such as neural tube defects. After birth, folate and cobalamin deficiency can cause anemia, failure to thrive, recurrent infections, psychiatric and neurological symptoms. The folate and the homocysteine metabolic pathways interact at a central step where 5-methyltetrahydrofolate donates its methyl group to homocysteine to produce methionine and tetrahydrofolate. Methyl cobalamin and folate interact at this critical step. Both nutrients have a crucial role in DNA synthesis and in delivering S-adenosylmethionine, the universal methyl donor. Severe and mild inherited disorders in folate and cobalamin pathways have been described. The two groups of disorders share some similarities, but differ in the molecular mechanism, metabolic dysregulation, and disease management. This review summarizes selected disorders, including rare and common mutations that affect folate and cobalamin absorption, transport, or dependent enzymes. When the mutations are discovered early enough, many of the described disorders are easily treatable by B vitamin supplementation, which often prevents or reverses the manifestation of the disease. Therefore, the screening for mutations is recommended and should be carried out as early as possible: after occurrence of the first symptoms or when a certain constellations of the folate and cobalamin related markers are measured, such as elevated homocysteine and/or methylmalonic acid.

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Familial Vitamin B<sub>12</sub> Malabsorption

Cited by 40 publications

References 1 publication

Homocystinuria: Studies in Tissue Culture

Homocystinuria: Studies in Tissue Culture

Studies of Patients with Familial Vitamin B<sub>12 </sub> Malabsorption

Genetic defects in folate and cobalamin pathways affecting the brain

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