Editing Abetalipoproteinemia (section)

== Presentation ==

===Symptoms===
Initial symptoms usually appear in infancy,<ref name="MedlinePlus 2018 k111">{{Cite web |date=February 1, 2018 |title=Abetalipoproteinemia |url=https://medlineplus.gov/genetics/condition/abetalipoproteinemia/ |access-date=April 22, 2024 |website=MedlinePlus |publisher=U.S. National Library of Medicine}}</ref><ref name="Burnett_2022" /> including:
* [[Failure to thrive]] (i.e. failure to grow in infancy)<ref name="pmid20953537">{{Cite journal |vauthors=Hasosah MY, Shesha SJ, Sukkar GA, Bassuni WY |date=October 2010 |title=Rickets and dysmorphic findings in a child with abetalipoproteinemia |journal=Saudi Medical Journal |volume=31 |issue=10 |pages=1169–71 |pmid=20953537}}</ref>
* [[Steatorrhea]] (i.e. fatty, pale stools)<ref name="pmid20953537" /><ref name="pmid20626336">{{Cite journal |vauthors=Moutzouri E, Elisaf M, Liberopoulos EN |date=March 2011 |title=Hypocholesterolemia |journal=Current Vascular Pharmacology |volume=9 |issue=2 |pages=200–12 |doi=10.2174/157016111794519354 |pmid=20626336}}</ref>
* Frothy stools<ref name="pmid20953537" />
* Foul smelling stools<ref name="pmid20953537" />
* Protruding abdomen<ref name="Hussain_2023">{{Cite report |url=https://rarediseases.org/rare-diseases/abetalipoproteinemia/ |title=Abetalipoproteinemia |date=2023-02-17 |publisher=National Organization for Rare Disorders |access-date=2024-04-22 |vauthors=Hussain MM}}</ref>

The rate of occurrence of additional symptoms later in life varies and increases with age.<ref name="Burnett_2022">{{Cite book |title=Gene Reviews |vauthors=Burnett JR, Hooper AJ, Hegele RA |date=2018-10-25 |publisher=University of Washington |location=Seattle, WA, USA |chapter=Abetalipoproteinemia |pmid=30358967 |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK532447/}}</ref> These may include:
* [[Intellectual disability]]/developmental delay<ref name="Hussain_2023" />
* [[Ataxia]] (problems with balance and movement)<ref name="Burnett_2022" /><ref name="MedlinePlus 2018 k111" />
* Muscle weakness<ref name="Burnett_2022" />
* Slurred speech ([[dysarthria]])<ref name="MedlinePlus 2018 k111" />
* [[Lordosis]] (curved lower back) and [[kyphoscoliosis]] (curved upper back)<ref name="MedlinePlus 2018 k111" />
* Progressive decreased vision<ref name="Burnett_2022" /><ref name="MedlinePlus 2018 k111" />
* Reflex and proprioception problems<ref name="Burnett_2022" />

===Signs===
* [[Acanthocyte|Acanthocytosis]]<ref name="pmid20953537" /><ref name="pmid874076">{{Cite journal |vauthors=Cooper RA, Durocher JR, Leslie MH |date=July 1977 |title=Decreased fluidity of red cell membrane lipids in abetalipoproteinemia |journal=The Journal of Clinical Investigation |volume=60 |issue=1 |pages=115–21 |doi=10.1172/JCI108747 |pmc=372349 |pmid=874076}}</ref>
* [[Retinitis pigmentosa]]<ref name="MedlinePlus 2018 k111" />
* [[Hypocholesterolemia|Low blood cholesterol]]<ref name="pmid20626336" />

===Features===
Abetalipoproteinemia affects the absorption of dietary fats, [[cholesterol]], and certain [[vitamin]]s. People affected by this disorder are not able to make certain [[lipoprotein]]s, which are [[molecule]]s that consist of [[protein]]s combined with cholesterol and particular fats called [[triglyceride]]s. This leads to a multiple vitamin deficiency, affecting the fat-soluble [[Retinol|vitamin A]], [[vitamin D]], [[Tocopherol|vitamin E]], and [[vitamin K]].<ref name="titleAbetalipoproteinemia - Genetics Home Reference" /> However, many of the observed effects are due to vitamin E deficiency in particular.<ref name="titleAbetalipoproteinemia - Genetics Home Reference" />

[[Image:Acanthocytosis.jpg|thumb|[[Acanthocytosis]] in a patient with abetalipoproteinemia.]]
Signs and symptoms vary and present differently from person to person. In general, 80–99% of individuals exhibit malabsorption of fats and fat-soluble vitamins. Approximately 30–79% of people with the disease display symptoms related to abnormality of the retinal pigmentation, ataxia, muscular hypotonia or reduced tendon reflexes.<ref name="GARD" />

The signs and symptoms of abetalipoproteinemia appear in the first few months of life (because pancreatic lipase is not active in this period). They can include failure to gain weight and grow at the expected rate ([[failure to thrive]]); diarrhea; abnormal spiny red blood cells ([[acanthocyte|acanthocytosis]]); and fatty, foul-smelling stools ([[steatorrhea]]).<ref name="titleAbetalipoproteinemia - Genetics Home Reference" /> The stool may contain large chunks of fat and/or blood. Infants often present with gastrointestinal problems caused by the poor fat absorption, which also contributes to steatorrhea. Other features of this disorder may develop later in childhood and often impair the function of the nervous system. They can include poor muscle coordination, difficulty with balance and movement ([[ataxia]]),<ref name="titleAbetalipoproteinemia - Genetics Home Reference" /><ref name="Hentati">{{Cite book |title=Ataxic Disorders |vauthors=Hentati F, El-Euch G, Bouhlal Y, Amouri R |year=2012 |isbn=9780444518927 |series=Handbook of Clinical Neurology |volume=103 |pages=295–305 |chapter=Ataxia with vitamin E deficiency and abetalipoproteinemia |doi=10.1016/B978-0-444-51892-7.00018-8 |pmid=21827896}}</ref> and progressive degeneration of the [[retina]] (the light-sensitive layer in the posterior eye) that can progress to near-blindness (due to deficiency of vitamin A, retinol).<ref name="titleAbetalipoproteinemia - Genetics Home Reference" /> Adults in their thirties or forties may have increasing difficulty with balance and walking. Many of the signs and symptoms of abetalipoproteinemia result from a severe vitamin deficiency, especially vitamin E deficiency, which typically results in eye problems with degeneration of the spinocerebellar and dorsal column tracts.{{Citation needed|date=May 2021}}