Difference between revisions of "Vitamin B7 deficiency"

 
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* Intestinal flora synthesizes significant quantities of biotin.
 
* Intestinal flora synthesizes significant quantities of biotin.
 
* Biotin is recycled in the body and eventually lost in urine and feces.
 
* Biotin is recycled in the body and eventually lost in urine and feces.
* Biotin (Vitamin B7) is a cofactor in four major carboxylation reactions
+
 
 +
===Cofactor in four major carboxylation reactions===
 
# Acetyl-CoA Carboxylase (ACC) - Acetyl-CoA to Malonyl-CoA in Fatty Acid Synthesis
 
# Acetyl-CoA Carboxylase (ACC) - Acetyl-CoA to Malonyl-CoA in Fatty Acid Synthesis
 
# Pyruvate Carboxylase (PC) - Pyruvate to Oxaloacetate in Gluconeogenesis
 
# Pyruvate Carboxylase (PC) - Pyruvate to Oxaloacetate in Gluconeogenesis
 
# Propinoyl-CoA Carboxylase (PCC) - Propinoyl-CoA to Methylmalonyl-CoA in Odd Chain Fatty Acid Metabolism
 
# Propinoyl-CoA Carboxylase (PCC) - Propinoyl-CoA to Methylmalonyl-CoA in Odd Chain Fatty Acid Metabolism
 
# Methylcrotonyl CoA Carboxylase (MCC) - 3-Methylcrotonyl CoA to 3-Methylglutaconyl CoA in Leucine Metabolism
 
# Methylcrotonyl CoA Carboxylase (MCC) - 3-Methylcrotonyl CoA to 3-Methylglutaconyl CoA in Leucine Metabolism
* Biotin deficiency is relatively rare. Populations at risk:
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 +
===Biotin deficiency risk factors===
 
# Long-term Parenteral Nutrition
 
# Long-term Parenteral Nutrition
 
# Consumption of raw egg whites (bodybuilders or boxers)
 
# Consumption of raw egg whites (bodybuilders or boxers)
* Secondary biotin deficiency (Multiple Carboxylase Deficiency) is caused by two inherited defects in metabolism:
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 +
===Secondary biotin deficiency (Multiple Carboxylase Deficiency)===
 +
Is caused by two inherited defects in metabolism:
 
# Holocarboxylase Synthetase Deficiency -  Autosomal Recessive disorder. Holocarboxylase Synthetase is required to attach biotin to other molecules. Deficiency in this enzyme prevents cells from using Biotin.
 
# Holocarboxylase Synthetase Deficiency -  Autosomal Recessive disorder. Holocarboxylase Synthetase is required to attach biotin to other molecules. Deficiency in this enzyme prevents cells from using Biotin.
 
# Biotinidase Deficiency - Biotinidase is required to release Biotin that is bounded to protein.
 
# Biotinidase Deficiency - Biotinidase is required to release Biotin that is bounded to protein.
  
 
==Clinical Features==
 
==Clinical Features==
* Classical Presentation:
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===Classical Presentation===
** Dermatitis - specifically around eyes, nose, mouth
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* [[rash|Dermatitis]] - specifically around eyes, nose, mouth
** Alopecia
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* [[Alopecia]]
** Enteritis
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* Enteritis ([[diarrhea]], [[nausea/vomiting]])
** Neurological - including AMS, lethargy, hallucinations, paresthesias
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* Neurological - including [[AMS]], [[lethargy]], [[hallucinations]], [[paresthesias]]
* Holocarboxylase Synthetase Deficiency - presents in the first week of life with:
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** lethargy
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===Holocarboxylase Synthetase Deficiency===
** hypotonia
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Presents in the first week of life with:
** vomiting
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* [[altered mental status (peds)|Lethargy]]
* Biotinidase Deficiency - presents later in life with:
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* Hypotonia
** dermatitis
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* [[Vomiting]]
** neurological symptoms - ataxia, seizures, myoclonus, nystagmus
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** ketoacidosis
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===Biotinidase Deficiency===
 +
Presents later in life with:
 +
* [[rash|Dermatitis]]
 +
* Neurological symptoms - [[ataxia]], [[seizures]], myoclonus, [[nystagmus]]
 +
* [[Ketonemia|Ketoacidosis]]
  
 
==Differential Diagnosis==
 
==Differential Diagnosis==
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** Pyruvate Carboxylase Deficiency
 
** Pyruvate Carboxylase Deficiency
 
* Starvation
 
* Starvation
* Medication Use - Antibiotics or Anti-convulsants
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* Medication Use - [[Antibiotics]] or [[anticonvulsants]]
 
* Other vitamin deficiencies:
 
* Other vitamin deficiencies:
  
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***[[Wernicke-Korsakoff syndrome]]
 
***[[Wernicke-Korsakoff syndrome]]
 
**[[Vitamin B3 deficiency]] ([[Pellagra]])
 
**[[Vitamin B3 deficiency]] ([[Pellagra]])
 +
**[[Vitamin B7 deficiency]] (Biotin)
 
**[[Vitamin B9 deficiency]] (Folate)
 
**[[Vitamin B9 deficiency]] (Folate)
 
**[[Vitamin B12 deficiency]]
 
**[[Vitamin B12 deficiency]]
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==Management==
 
==Management==
* Supplementation of Biotin. Dosage is debated:
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* Supplementation of [[Biotin]]. Dosage is debated:
 
** 150 ug intramuscular injection suggested
 
** 150 ug intramuscular injection suggested
 
** 5-20 mg/dl have also been used
 
** 5-20 mg/dl have also been used
  
 
* Stop consumption of raw eggs.
 
* Stop consumption of raw eggs.
* Stop anti-convulsant or anti-biotic use.
+
* Stop culprit anti-convulsant or anti-biotic
  
 
==Disposition==
 
==Disposition==
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==See Also==
 
==See Also==
 
+
*[[Vitamin deficiencies]]
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*[[Inborn errors of metabolism]]
  
 
==External Links==
 
==External Links==

Latest revision as of 17:02, 29 September 2019

Background

  • Almost all food contain significant quantities of biotin, but it is most found in plants, liver, egg yolk, soybean products, and yeast.
  • Daily biotin requirement is low (150-300 ug/d).
  • Intestinal flora synthesizes significant quantities of biotin.
  • Biotin is recycled in the body and eventually lost in urine and feces.

Cofactor in four major carboxylation reactions

  1. Acetyl-CoA Carboxylase (ACC) - Acetyl-CoA to Malonyl-CoA in Fatty Acid Synthesis
  2. Pyruvate Carboxylase (PC) - Pyruvate to Oxaloacetate in Gluconeogenesis
  3. Propinoyl-CoA Carboxylase (PCC) - Propinoyl-CoA to Methylmalonyl-CoA in Odd Chain Fatty Acid Metabolism
  4. Methylcrotonyl CoA Carboxylase (MCC) - 3-Methylcrotonyl CoA to 3-Methylglutaconyl CoA in Leucine Metabolism

Biotin deficiency risk factors

  1. Long-term Parenteral Nutrition
  2. Consumption of raw egg whites (bodybuilders or boxers)

Secondary biotin deficiency (Multiple Carboxylase Deficiency)

Is caused by two inherited defects in metabolism:

  1. Holocarboxylase Synthetase Deficiency - Autosomal Recessive disorder. Holocarboxylase Synthetase is required to attach biotin to other molecules. Deficiency in this enzyme prevents cells from using Biotin.
  2. Biotinidase Deficiency - Biotinidase is required to release Biotin that is bounded to protein.

Clinical Features

Classical Presentation

Holocarboxylase Synthetase Deficiency

Presents in the first week of life with:

Biotinidase Deficiency

Presents later in life with:

Differential Diagnosis

  • DDx involves genetic disorders with impaired carboxylation.
    • Biotinidase Deficiency (see above)
    • Holocarboxylase Synthetase Deficiency (see above)
    • Carnitine Deficiency
    • Methylmalonic Acidemia
    • Propionic Acidemia
    • Pyruvate Carboxylase Deficiency
  • Starvation
  • Medication Use - Antibiotics or anticonvulsants
  • Other vitamin deficiencies:

Vitamin deficiencies

Evaluation

  • Diagnosis is primarily clinical. Routine serum chemistry panel should be checked.
  • Other Laboratory Studies
    • Newborn Screening
    • Serum Biotinidase Activity decreased
    • Serum Ammonia Levels increased
    • Plasma Carnitine
    • Quantitative Amino Acid levels
    • Urine B-Hydroxyisoverlate decreased
    • Urine Biotin decreased
    • Urine Ketones increased

Management

  • Supplementation of Biotin. Dosage is debated:
    • 150 ug intramuscular injection suggested
    • 5-20 mg/dl have also been used
  • Stop consumption of raw eggs.
  • Stop culprit anti-convulsant or anti-biotic

Disposition

  • Follow-up with primary care provider or referral to genetic specialist.

See Also

External Links

References