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* Convergent evolution of lactase persistence is seen in some populations in Africa that domesticate cows and consume milks product into adulthood <ref name="pmid17159977">{{cite journal |vauthors=Tishkoff SA, Reed FA, Ranciaro A, Voight BF, Babbitt CC, Silverman JS, Powell K, Mortensen HM, Hirbo JB, Osman M, Ibrahim M, Omar SA, Lema G, Nyambo TB, Ghori J, Bumpstead S, Pritchard JK, Wray GA, Deloukas P |title=Convergent adaptation of human lactase persistence in Africa and Europe |journal=Nat. Genet. |volume=39 |issue=1 |pages=31–40 |year=2007 |pmid=17159977 |pmc=2672153 |doi=10.1038/ng1946 |url=}}</ref>   
* Convergent evolution of lactase persistence is seen in some populations in Africa that domesticate cows and consume milks product into adulthood <ref name="pmid17159977">{{cite journal |vauthors=Tishkoff SA, Reed FA, Ranciaro A, Voight BF, Babbitt CC, Silverman JS, Powell K, Mortensen HM, Hirbo JB, Osman M, Ibrahim M, Omar SA, Lema G, Nyambo TB, Ghori J, Bumpstead S, Pritchard JK, Wray GA, Deloukas P |title=Convergent adaptation of human lactase persistence in Africa and Europe |journal=Nat. Genet. |volume=39 |issue=1 |pages=31–40 |year=2007 |pmid=17159977 |pmc=2672153 |doi=10.1038/ng1946 |url=}}</ref>   
* Persistence of intestinal lactase until adulthood is inherited as autosomal-dominant characteristic<ref name="pmid3140651">{{cite journal |vauthors=Scrimshaw NS, Murray EB |title=The acceptability of milk and milk products in populations with a high prevalence of lactose intolerance |journal=Am. J. Clin. Nutr. |volume=48 |issue=4 Suppl |pages=1079–159 |year=1988 |pmid=3140651 |doi= |url=}}</ref>   
* Persistence of intestinal lactase until adulthood is inherited as autosomal-dominant characteristic<ref name="pmid3140651">{{cite journal |vauthors=Scrimshaw NS, Murray EB |title=The acceptability of milk and milk products in populations with a high prevalence of lactose intolerance |journal=Am. J. Clin. Nutr. |volume=48 |issue=4 Suppl |pages=1079–159 |year=1988 |pmid=3140651 |doi= |url=}}</ref>   
* In particular, presence of the T allele of the SNP located at -13.9 kb upstream of the lactase gene has been strongly correlated with lactase persistence 
* Multiple single nucleotide polymorphisms (SNPs) in the DNA sequence of the coding region and the regulatory region of the lactase gene on 2q21 have been identified.   
* Multiple single nucleotide polymorphisms (SNPs) in the DNA sequence of the coding region and the regulatory region of the lactase gene on 2q21 have been identified.   
* Several in vitro studies have suggested that this allele regulates levels of lactase mRNA and thus lactase persistence 
*  A CC genotype at -13910 C/T polymorphism is associated with acquired primary lactase deficiency (adult-type hypolactasia), whereas TC and TT genotypes are linked with lactase persistence 
OR
OR
*[Disease name] may be classified into [large number > 6] subtypes based on:  
*[Disease name] may be classified into [large number > 6] subtypes based on:  

Revision as of 14:44, 28 November 2017

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mahda Alihashemi M.D. [2]

Overview

There is no established system for the classification of [disease name].

OR

[Disease name] may be classified according to [classification method] into [number] subtypes/groups: [group1], [group2], [group3], and [group4].

OR

[Disease name] may be classified into [large number > 6] subtypes based on [classification method 1], [classification method 2], and [classification method 3]. [Disease name] may be classified into several subtypes based on [classification method 1], [classification method 2], and [classification method 3].

OR

Based on the duration of symptoms, [disease name] may be classified as either acute or chronic.

OR

If the staging system involves specific and characteristic findings and features: According to the [staging system + reference], there are [number] stages of [malignancy name] based on the [finding1], [finding2], and [finding3]. Each stage is assigned a [letter/number1] and a [letter/number2] that designate the [feature1] and [feature2].

OR

The staging of [malignancy name] is based on the [staging system].

OR

There is no established system for the staging of [malignancy name].

Classification

  • There is no established system for the classification of [disease name].

OR

  • Lactose intolerance may be classified according to its causes into 2 groups:
    • Primary lactose malabsorption 
    • Secondary lactose malabsorption
  • Primary lactose malabsorption may be classified into 3 subtypes include:
    • Acquired primary lactase deficiency 
    • Congenital lactase deficiency
    • Developmental lactase deficiency

Acquired primary lactase deficiency (adult-type hypolactasia, lactase nonpersistence)

  • The most common cause of primary lactase malabsorbtion
  • Autosomal recessive condition[1]
  • Intestinal lactase levels is deceresed at preschool age in many populations especially in Asia and Africa
  • Elevated lactase activity is maintained in Caucasians such as northern European
  • Convergent evolution of lactase persistence is seen in some populations in Africa that domesticate cows and consume milks product into adulthood [2]
  • Persistence of intestinal lactase until adulthood is inherited as autosomal-dominant characteristic[3]
  • In particular, presence of the T allele of the SNP located at -13.9 kb upstream of the lactase gene has been strongly correlated with lactase persistence
  • Multiple single nucleotide polymorphisms (SNPs) in the DNA sequence of the coding region and the regulatory region of the lactase gene on 2q21 have been identified.
  • Several in vitro studies have suggested that this allele regulates levels of lactase mRNA and thus lactase persistence
  •  A CC genotype at -13910 C/T polymorphism is associated with acquired primary lactase deficiency (adult-type hypolactasia), whereas TC and TT genotypes are linked with lactase persistence

OR

  • [Disease name] may be classified into [large number > 6] subtypes based on:
    • [Classification method 1]
    • [Classification method 2]
    • [Classification method 3]
  • [Disease name] may be classified into several subtypes based on:
    • [Classification method 1]
    • [Classification method 2]
    • [Classification method 3]

OR

  • Based on the duration of symptoms, [disease name] may be classified as either acute or chronic.

OR

  • If the staging system involves specific and characteristic findings and features:
  • According to the [staging system + reference], there are [number] stages of [malignancy name] based on the [finding1], [finding2], and [finding3]. Each stage is assigned a [letter/number1] and a [letter/number2] that designate the [feature1] and [feature2].

OR

  • The staging of [malignancy name] is based on the [staging system].

OR

  • There is no established system for the staging of [malignancy name].

References

  1. Enattah NS, Sahi T, Savilahti E, Terwilliger JD, Peltonen L, Järvelä I (2002). "Identification of a variant associated with adult-type hypolactasia". Nat. Genet. 30 (2): 233–7. doi:10.1038/ng826. PMID 11788828.
  2. Tishkoff SA, Reed FA, Ranciaro A, Voight BF, Babbitt CC, Silverman JS, Powell K, Mortensen HM, Hirbo JB, Osman M, Ibrahim M, Omar SA, Lema G, Nyambo TB, Ghori J, Bumpstead S, Pritchard JK, Wray GA, Deloukas P (2007). "Convergent adaptation of human lactase persistence in Africa and Europe". Nat. Genet. 39 (1): 31–40. doi:10.1038/ng1946. PMC 2672153. PMID 17159977.
  3. Scrimshaw NS, Murray EB (1988). "The acceptability of milk and milk products in populations with a high prevalence of lactose intolerance". Am. J. Clin. Nutr. 48 (4 Suppl): 1079–159. PMID 3140651.

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Lactose Intolerance Microchapters

Home

Patient Information

Overview

Historical Perspective

Classification

Pathophysiology

Causes

Differentiating Lactose Intolerance from Other Diseases

Epidemiology and Demographics

Risk Factors

Screening

Natural History, Complications and Prognosis

Diagnosis

Diagnostic Study of Choice

History and Symptoms

Physical Examination

Laboratory Findings

Electrocardiogram

Chest X Ray

CT

MRI

Echocardiography or Ultrasound

Other Imaging Findings

Other Diagnostic Studies

Treatment

Medical Therapy

Surgery

Primary Prevention

Secondary Prevention

Cost-Effectiveness of Therapy

Future or Investigational Therapies

Case Studies

Case #1

Lactose intolerance classification On the Web

Most recent articles

Most cited articles

Review articles

CME Programs

Powerpoint slides

Images

American Roentgen Ray Society Images of Lactose intolerance classification

All Images
X-rays
Echo & Ultrasound
CT Images
MRI

Ongoing Trials at Clinical Trials.gov

US National Guidelines Clearinghouse

NICE Guidance

FDA on Lactose intolerance classification

CDC on Lactose intolerance classification

Lactose intolerance classification in the news

Blogs on Lactose intolerance classification

Directions to Hospitals Treating Lactose intolerance

Risk calculators and risk factors for Lactose intolerance classification

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [3]

Overview

There are three major types of lactose intolerance.[1] They are primary lactose intolerance, secondary lactose intolerance and congenital lactase deficiency.

Classification

There are three major types of lactose intolerance:[1]

  1. Primary lactose intolerance: Environmentally induced by weaning in non dairy consuming societies. In most Asian and African cultures, mother's milk is the only commonly available milk and so milk consumption beyond infancy is not commonplace, therefore children become weaned, which is the same weaning process for all mammals (domesticated and wild). However societies such as the japanese where milk consumption has been on the increase, demonstrate that notwithstanding the genetic predisposition to lactose intolerance, they now present lower prevalence of lactose intolerance.[2] For any given individual the degree of weaning is probably genetically influenced.
  2. Secondary lactose intolerance: Environmentally induced, resulting from certain gastrointestinal diseases, including exposure to intestinal parasites such as giardia.[3][4] In such cases the production of lactase may be permanently disrupted.[5]
  3. Congenital lactase deficiency present at birth and diagnosed in early infancy.

References

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