Sorted By Test Name - Mayo Medical Laboratories

PMMIF
89657
fatty acids derived from phosphatidylcholine. LCAT deficiency results in a lack of remodeling of primary
lipoprotein particles, affecting eventual cholesterol uptake and elimination. In cases of deficiency of
LCAT, the concentration of lecithin in the serum are increased several-fold. Clinical findings in LCAT
deficiency include corneal opacities, anemia, and frequently, proteinuria. The disorder is inherited as an
autosomal recessive trait. Early atherosclerosis develops in many individuals with this disorder. In
addition, sphingomyelin normally comprises about 5% to 20% of the total phospholipids of serum. In
Niemann-Pick Type A and B diseases, sphingomyelin accumulates in visceral and neural tissues and may
become increased in the serum. Other disorders involving alterations of the concentration, composition,
and/or lipoprotein distribution include: abeta- or hypobetalipoproteinemia, Tangier disease, or fish eye
disease.
Useful For: First-order test in the diagnosis of lecithin-cholesterol acyltransferase deficiency
Interpretation: Elevated in cases of lecithin-cholesterol acyltransferase deficiency deficiency due to
elevations of lecithin
Reference Values:
155-275 mg/dL
Reference values have not been established for patients that are less than 16 years of age.
Clinical References: 1. Baehorik PS, Levy RI, Rifkind BM: Lipids and dyslipoproteinemia. In
Clinical Diagnosis and Management by Laboratory Methods. 18th Edition. Edited by JB Henry.
Philadelphia, WB Saunders Company, 1991, p 198 2. Norum KR, Gjone E, Glomset JA: Familial lecithin:
cholesterol acyltransferase deficiency, including fish eye disease. In The Metabolic Basis of Inherited
Disease. 6th Edition. Edited by CR Scriver, AL Beaudet, WS Sly, D Valle. New York, McGraw-Hill
Book Company, 1989, pp 1181-1194
Phosphomannomutase (PMM) and Phosphomannose
Isomerase (PMI), Fibroblasts
Clinical Information: Congenital disorders of glycosylation (CDG), formerly known as
carbohydrate-deficient glycoprotein syndrome, are a group of inherited metabolic diseases that affect 1 of
the steps of the pathway involved in glycosylation. CDGs typically present as multisystemic disorders
with developmental delay, hypotonia, abnormal magnetic resonance imaging (MRI) findings,
hypoglycemia, and protein-losing enteropathy. There is considerable variation in the severity of this group
of diseases, which can range from hydrops fetalis to a mild presentation in adults. In some subtypes (Ib, in
particular) intelligence is not compromised. Phosphomannomutase-2 deficiency (CDG-Ia or
PMM2-CDG) is an autosomal recessive glycosylation disorder resulting from reduced or absent activity
of the enzyme phosphomannomutase-2, encoded by the PMM2 gene. Over 700 individuals have been
described to date, making it the most common congenital disorder CDG worldwide. All patients with
CDG-Ia have a neurological manifestation of disease with variable involvement of other organ systems.
Individuals with this disorder typically present in the neonatal period with failure to thrive, developmental
delay, abnormal subcutaneous fat distribution, elevated liver transaminases, and abnormal MRI findings.
Currently, there is no cure and treatment remains primarily supportive and symptomatic.
Phosphomannose isomerase deficiency (CDG-Ib or MPI-CDG) is an autosomal recessive glycosylation
disorder resulting from reduced or absent activity of phosphomannose isomerase, an enzyme encoded by
the MPI gene. This subtype of CDG is unique in that there is little to no involvement of the central
nervous system. The primary clinical manifestations are a result of aberrant gastrointestinal function. In
particular, individuals with CDG-Ib may present with failure to thrive, hypoglycemia, chronic diarrhea,
and protein-losing enteropathy. Although CDG-Ib can be life threatening, it can be effectively treated
with mannose supplementation.
Useful For: Diagnosis of congenital disorders of glycosylation Ia (phosphomannomutase-2 deficiency
[CDG-Ia or PMM2-CDG]) and Ib (phosphomannose isomerase deficiency [CDG-Ib or MPI-CDG]) as
measured in fibroblasts A follow-up test for patients with an abnormal transferrin isoform profile as
determined by isoelectric focusing or liquid chromatography-mass spectrometry (eg, CDG/89891
Carbohydrate Deficient Transferrin for Congenital Disorders of Glycosylation, Serum)
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