Abetalipoproteinemia

Abetalipoproteinemia is an inherited disorder that affects the absorption of dietary fats, cholesterol, and fat-soluble vitamins. People affected by this disorder are not able to make certain lipoproteins, which are particles that carry fats and fat-like substances (such as cholesterol) in the blood. Specifically, people with abetalipoproteinemia are missing a group of lipoproteins called beta-lipoproteins. An inability to make beta-lipoproteins causes severely reduced absorption (malabsorption) of dietary fats and fat-soluble vitamins (vitamins A, D, E, and K) from the digestive tract into the bloodstream. Sufficient levels of fats, cholesterol, and vitamins are necessary for normal growth, development, and maintenance of the body's cells and tissues, particularly nerve cells and tissues in the eye.The signs and symptoms of abetalipoproteinemia appear in the first few months of life. They can include failure to gain weight and grow at the expected rate (failure to thrive); diarrhea; abnormal star-shaped red blood cells (acanthocytosis); and fatty, foul-smelling stools (steatorrhea). Other features of this disorder may develop later in childhood and often impair the function of the nervous system. Disturbances in nerve function may cause affected people to eventually develop poor muscle coordination and difficulty with balance and movement (ataxia). Individuals with this condition may also develop an eye disorder called retinitis pigmentosa, in which progressive degeneration of the light-sensitive layer (retina) at the back of the eye can cause vision loss. 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 a deficiency of vitamin E.

Different Conditions

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Disorders of lipoprotein metabolism or certain specified lipidaemias

Disorders characterised by low level of lipoproteins of any type in the blood

Where It Occurs

Metabolic System|Nutritional System

Abbreviated Terms

  • High-density lipoprotein deficiency
  • cholesterol thesaurismosis
  • high-density lipoid deficiency
  • Dyslipidemia, depressed HDL cholesterol
  • ABL - [abetalipoproteinemia]
  • Also Known As

  • Lipoprotein deficiency
  • Hypolipidaemia
  • hypolipoproteinemia
  • lipoprotein deficiency disorder
  • Related ICD 10 COde
    ICD 10 Code E78.6

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    Familial hypoalphalipoproteinaemia

    This refers to the deficiency in a protein that in humans is encoded by the APOA1 gene. It has a specific role in lipid metabolism.
    Related ICD 10 COde
    ICD 10 Code E78.6

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    Familial hypobetalipoproteinaemia

    This refers to a truncated form of the primary apolipoproteins of chylomicrons and low-density lipoproteins (LDL - known commonly by the misnomer "bad cholesterol" when in reference to heart disease), which is responsible for carrying cholesterol to tissues.
    Related ICD 10 COde
    ICD 10 Code E78.6

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    Familial lecithin-cholesterol acyltransferase deficiency

    Fish eye disease (FED) is a form of genetic LCAT (lecithin-cholesterol acyltransferase) deficiency characterized clinically by corneal opacifications, and biochemically by significantly reduced HDL cholesterol and partial LCAT enzyme deficiency.

    Where It Occurs

    Metabolic System|Visual System

    Also Known As

  • Ophtalmic ichthyosis
  • Partial lecithin-cholesterol acyltransferase deficiency
  • Dyslipoproteinaemic corneal dystrophy
  • Partial LCAT - [lecithin-cholesterol acyltransferase] deficiency
  • Related ICD 10 COde
    ICD 10 Code E78.6

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    Genetic disorders of adipose tissue or lipid metabolism affecting the skin

    Hypobetalipoproteinemia (HBL) constitutes a group of lipoprotein metabolism disorders that are characterized by permanently low levels (below the 5th percentile) of apolipoprotein B and LDL cholesterol. There are two types of HBL: familial hypobetalipoproteinemia and chylomicron retention disease (CMRD; see these terms). The familial form can be severe with early onset (abetalipoproteinemia/homozygous familial hypobetalipoproteinemia; see this term) or benign (benign familial hypobetalipoproteinemia; see this term). (Please add the sentence). Severe familial HBL and CMRD appear in infancy or childhood. As a result they are often associated with growth delay, diarrhoea with steatorrhoea, and fat malabsorption. Benign familial hypobetalipoproteinemia is generally asymptomatic, but in adults is occasionally associated with dietary intolerance to fat. HBL disorders are caused by mutations in proteins involved in the synthesis, secretion and catabolism of lipoproteins containing apolipoprotein B (LDL, VLDL and chylomicrons).

    Additional Information

    Hypobetalipoproteinemia (HBL) constitutes a group of lipoprotein metabolism disorders that are characterized by permanently low levels (below the 5th percentile) of apolipoprotein B and LDL cholesterol. HBL affects around 1/1,000 individuals. There are two types of HBL: familial hypobetalipoproteinemia and chylomicron retention disease (CMRD; see these terms). The familial form can be severe with early onset (abetalipoproteinemia/homozygous familial hypobetalipoproteinemia; see this term) or benign (benign familial hypobetalipoproteinemia; see this term). Severe familial HBL and CMRD appear in infancy or childhood. As a result they are often associated with growth delay, diarrhea with steatorrhea, and fat malabsorption. Infants with severe familial hypobetalipoproteinemia have hepatomegaly with steatosis, spastic ataxia, atypical retinitis pigmentosa, acanthocytosis, low levels of liposoluble vitamins (A, E and K), and major cytolysis and even cirrhosis. Benign familial hypobetalipoproteinemia is generally asymptomatic, but in adults is occasionally associated with dietary intolerance to fat, steatorrhea after oral intake of lipids, moderate cytolysis, cholelithiasis, moderately low levels of liposoluble vitamins and acanthocytosis. Moderate hepatic steatosis and paresthesia of the extremities are sometimes observed. HBL disorders are caused by mutations in proteins involved in the synthesis, secretion and catabolism of lipoproteins containing apolipoprotein B (LDL, VLDL and chylomicrons). Abetalipoproteinemia is inherited in a recessive manner and is a result of mutations of two alleles of the MTTP gene (MTP; 4q24). Other severe early familial hypobetalipoproteinemias are inherited in a codominant manner and are a result of mutations of two alleles of the APOB gene (2p24-p23). Benign familial hypobetalipoproteinemia, which is also inherited in a codominant manner, can be caused by heterozygous mutations of the APOB gene or the PCSK9 gene (1p34.1-p32). CMRD, which is inherited in an autosomal recessive manner, is caused by mutations of two alleles of the SAR1B gene (SARA2; 5q31.1). Diagnosis of familial hypobetalipoproteinemia is based on lipid analysis, after 12 hours of fasting, carried out on the patient and their parents to measure serum levels of LDL (<0.10g/L for the severe form; <0.80g/L for the moderate form), triglycerides (<0.20 g/L for the severe form; <0.50g/L for the moderate form), and apolipoprotein B (<0.10g/L for the severe form; <0.50g/L for the moderate form). Evaluation of steatorrhea and truncated apolipoprotein B after oral lipid intake, measurement of liposoluble vitamins (A, E, K), testing for acanthocytosis (on blood smears), complete neurological examination, hepatic ultrasound and eye examination can also be carried out. Diagnosis of CMRD is based on the absence in serum, after oral lipid intake, of intestinal apolipoprotein B (ApoB-48) and the appearance of `white intestine' seen endoscopically. Differential diagnoses of HBL include metabolic diseases with hepatic overload, with steatosis and/or hepatomegaly, atypical diseases of the central and peripheral nervous system, and secondary causes of hypocholesterolemia (iatrogenic or systemic). Prenatal diagnosis is feasible when the causal mutations in both parents are known. Management of the moderate forms of HBL includes reduction of the proportion of fat in the patient's diet and vitamin E supplementation. Management of the severe forms of HBL and CMRD should take place in specialized centers. The prognosis of HBL is severe when the disease manifests in early childhood, and is excellent for the moderate form without cytolysis and steatosis. A familial syndrome of longevity has been observed in the benign forms of HBL (many patients live over the age of 85).

    Where It Occurs

    Metabolic System|Nutritional System
    Related ICD 10 COde
    ICD 10 Code E78.6

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    Related ICD 10 COde
    ICD 10 Code E78.6

    ----------------------

    Hypobetalipoproteinaemia

    Abetalipoproteinemia/ homozygous familial hypobetalipoproteinemia (ABL/HoFHBL) is a severe form of familial hypobetalipoproteinemia (see this term) characterized by permanently low levels (below the 5th percentile) of apolipoprotein B and LDL cholesterol, and by growth delay, malabsorption, hepatomegaly, and neurological and neuromuscular manifestations. Abetalipoproteinemia is inherited in a recessive manner and is a result of mutations of two alleles of the MTTP gene (MTP; 4q24). Other severe early familial hypobetalipoproteinemias are inherited in a codominant manner and are a result of mutations of two alleles of the APOB gene (2p24-p23).

    Additional Information

    Abetalipoproteinemia/ homozygous familial hypobetalipoproteinemia (ABL/HoFHBL) is a severe form of familial hypobetalipoproteinemia (see this term) characterized by permanently low levels (below the 5th percentile) of apolipoprotein B and LDL cholesterol, and by growth delay, malabsorption, hepatomegaly, and neurological and neuromuscular manifestations. It is very rare, with an estimated prevalence of less than 1/1,000,000. ABL/HoFHBL manifests during the first year of life or in young childhood. It is often associated with growth delay, hepatomegaly with steatosis, diarrhea with steatorrhea, and fat malabsorption. Spastic ataxia, atypical retinitis pigmentosa, acanthocytosis, a low level of liposoluble vitamins, and major cytolysis and even cirrhosis can occur. Abetalipoproteinemia is inherited in a recessive manner and is a result of mutations of two alleles of the MTTP gene (MTP; 4q24). Other severe early familial hypobetalipoproteinemias are inherited in a codominant manner and are a result of mutations of two alleles of the APOB gene (2p24-p23). Diagnosis is based on lipid analysis, after 12 hours of fasting, carried out on the patient and their parents to measure serum levels of LDL (<0.10g/L), triglycerides (<0.20 g/L), and apolipoprotein B (<0.10g/L). Identification of steatorrhea and truncated apolipoprotein B after oral lipid intake, measurement of liposoluble vitamins (A, E, K), testing for acanthocytosis (on blood smears), complete neurological examination, hepatic ultrasound and eye examination can also be carried out. Identification of mutations of the MTTP or APOB genes confirms the diagnosis. Differential diagnoses include metabolic diseases with hepatic overload, with steatosis and/or hepatomegaly, atypical diseases of the central and peripheral nervous system, and secondary causes of hypocholesterolemia (iatrogenic or systemic). Prenatal diagnosis is possible when the causal mutations in both parents are known. Management should be undertaken in specialized centers. The prognosis is severe, with a significantly reduced life expectancy.

    Where It Occurs

    Metabolic System|Nutritional System

    Also Known As

  • Homozygous familial hypobetalipoproteinaemia
  • Bassen-Kornzweig disease
  • Apolipoprotein B deficiency
  • Related ICD 10 COde
    ICD 10 Code E78.6

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    Hypolipoproteinaemia

    This is the disorder of lipoprotein metabolism. Lecithin cholesterol acyltransferase catalyzes the formation of cholesterol esters in lipoproteins.

    Additional Information

    Lecithin-cholesterol-acyl transferase (LCAT) deficiency is a disorder of lipoprotein metabolism characterized by inadequate esterification of plasmatic cholesterol. LCAT is a plasmatic enzyme bound to high density lipoproteins (HDL) and lipoproteins containing apoliprotein B (very low density lipoprotein, VLDL, and low density lipoprotein, LDL). LCAT catalyses the transesterification of free cholesterol and lecithin. LCAT deficiency is rare and only 30 cases have been reported in the literature. There are two clinical forms of LCAT deficiency: familial LCAT deficiency, which is associated with a complete absence of LCAT resulting in esterification anomalies involving both HDL (alpha-LCAT activity) and LDL (beta-LCAT activity), and fish-eye disease resulting from a partial LCAT deficiency that affects only alpha-LCAT activity. Both conditions are marked by low plasma HDL levels and corneal clouding due to accumulation of cholesterol deposits in the cornea ('fish-eye'). Corneal opacity is often present at birth, beginning at the periphery of the cornea and progressing gradually to the centre. The dyslipoproteinaemia is sometimes atherogenic and the opacities in the cornea may need to be treated by corneal transplantation. Familial LCAT deficiency is associated with hypertriglyceridaemia, normochromic heamolytic anemia, and proteinuria. The prognosis for this form depends on the extent to which the disease affects renal function: the accumulation of abnormal lipoproteins (LpX) in the kidneys may lead to renal insufficiency. The condition is transmitted as an autosomal recessive trait, but sporadic cases have also been reported. To date, around 40 mutations in the LCAT gene (localised to 16q22.1) have been described, leading to either a total or partial LCAT deficiency. However, it should be noted that fish-eye disease may also be associated with mutations in the apolipoprotein A-I gene.

    Where It Occurs

    Metabolic System|Nutritional System

    Abbreviated Terms

  • LCAT - [lecithin-cholesterol acyltransferase] deficiency
  • Related ICD 10 COde
    ICD 10 Code E78.6

    ----------------------

    Lecithin-cholesterol acyltransferase deficiency

    This is the disorder of lipoprotein metabolism. Lecithin cholesterol acyltransferase catalyzes the formation of cholesterol esters in lipoproteins.

    Where It Occurs

    Metabolic System|Nutritional System
    Related ICD 10 COde
    ICD 10 Code E78.6

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