Rare congenital disorder that causes the body to not
produce chylomicrons, low-density lipoprotein (LDL), and very-low-density
lipoprotein (VLDL). Coagulation disorder, demyelination and ataxia,
peripheral sensory neuropathy, retinitis pigmentosa, acanthocytosis,
diminished response to local anesthetics.
Bassen-Kornzweig Syndrome; Acanthocytosis; Microsomal
Triglyceride Transfer Protein Deficiency.
Unknown. Males are approximately 1.5 times more often
affected than females.
Autosomal recessive. Abetalipoproteinemia is
caused by mutations in the gene responsible for microsomal triglyceride
transfer protein (MTP). MTP is thought to transfer lipids to the apo-β
protein as it is translated, allowing it to attain the proper conformation
for lipoprotein assembly. Gene locus is on chromosome 4q22-24.
Beta lipoproteins are lipoproteins of various
molecular weights, with apo-100 (essential component of VLDL and LDL) and
apo-48 (mainly in chylomicrons) as their principal subtypes. These
lipoproteins bind to specific receptors on human cells, allowing exchange of
lipids. Virtual absence of VLDLs and LDLs results in low levels of plasma
cholesterol and triglycerides. However, cholesterol delivery to individual
cells remains normal by an increased cholesterol-carrying capacity of the
high-density lipoproteins (HDLs). Although the basal cortisol secretion in
the adrenal cortex is normal, its maximal rate cannot be reached with
Based on the clinical course, reduced plasma lipids
(electrophoresis), and absent apo-β. A peripheral smear shows 50%
acanthocytosis and hyperbilirubinemia (reduced red cell lifespan). Sural
nerve biopsy reveals loss of large myelinated fibers.
Age of onset is the first year of life
(gastrointestinal manifestations). Within the first 10 years, neurologic and
ocular manifestations appear. Fat malabsorption (chronic diarrhea) is
severe. Spinocerebellar ataxia, peripheral neuropathy, pigmented
retinopathy, and ceroid myopathy are secondary to tocopherol transport
defect in the blood. Muscle dysfunction resulting in pes cavus and
kyphoscoliosis is common. Fatal cardiomyopathy has been described. Treatment
is supportive only with fat-soluble vitamin supplements (A, D, E, K) and
tocopherols. Use of triglyceride containing long-chain fatty acids has been
Evaluate the extent of neurologic
deficit. Check pulmonary function with SpO2, FEV1, and forced
vital capacity; chest radiograph; arterial blood gas analysis. Laboratory
investigations show anemia (resulting from iron and/or folate deficiency,
autohemolysis) and prolonged prothrombin time (resulting from vitamin K
deficiency, liver cirrhosis) but normal platelet function. Electrolyte
changes may be present (because of potential adrenal dysfunction and
vomiting and diarrhea as part of the fat malabsorption). Assess cardiac
function (ECG, chest radiograph, echocardiogram for ventricular function).
Hypoalbuminemia (caloric and protein malnutrition) and reduced α1-acid glycoprotein levels may be present.
A rapid sequence induction technique is
indicated in the presence of vomiting. High risk for cardiorespiratory
failure in patients with severe lung and cardiac disease. Muscle weakness
from myopathy and malnutrition may confound the problem. Regional anesthesia
is contraindicated if coagulation is not within the normal range.
Use of succinylcholine can be
dangerous if neuropathy or myopathy is present (a fast nondepolarizing
neuromuscular agent ...