Test Catalog

Interpretive Handbook

Test 62237 :
Oligosaccharidoses Screen, Leukocytes

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Oligosaccharidoses are a group of autosomal recessively inherited lysosomal disorders of glycoprotein catabolism. There is no treatment available at this time for these disorders. Details about the different oligosaccharidoses detected by this screening test are provided in the Table.

 

Table Conditions identifiable by method(1):

 

Disorder

Onset

Gene

Enzyme Deficiency

Worldwide Incidence

Alpha-mannosidosis

Infancy (severe, Type I)

Adult (mild, Type II)

Prenatal (severe, Type III)

MAN2B1

Alpha- mannosidase (alpha-Mann)

1:500,000

Phenotype: highly variable; "mild" Hurler-like features, learning difficulties, hepatosplenomegaly, deafness, immune deficiency.

Beta-mannosidosis

Infancy to adolescence

MANBA

Beta-mannosidase (beta-Mann)

<30 patients described

Phenotype: highly variable; learning difficulties, deafness, frequent infections

Alpha-fucosidosis

Infancy to early childhood

FUCA1

Alpha-fucosidase (alpha-Fuc)

<100 patients described

Phenotype: highly variable; psychomotor retardation, coarse facial features, growth delay; angiokeratoma, elevated sweat chloride

GM1 gangliosidosis (a sphingolipidosis)

Infancy (severe, Type I; intermediate, Type II)

Adult (mild, Type III)

GLB1

Beta-galactosidase (beta-Gal)

1:200,000

Phenotype: fetal hydrops/neonatal cardiomyopathy to early developmental delay/arrest, facial coarseness, hepatosplenomegaly, failure to thrive, to second/third decade onset of ataxia, speech abnormalities leading to spinocerebellar degeneration and cognitive decline. Cherry-red spot in early onset variants

Mucopolysaccharidosis type IVB (Morquio B)

Childhood

GLB1

Beta-galactosidase (beta-Gal)

<30 patients described

Phenotype: dwarfism with scoliosis and vertebral deformities noted between 1 and 4 years old and progressively worsening; typically no central nervous system involvement; keratan sulfate excretion in urine

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Useful For Suggests clinical disorders or settings where the test may be helpful

Screening for a subset of oligosaccharidoses in leukocytes

Interpretation Provides information to assist in interpretation of the test results

This is a screening test; not all oligosaccharidoses are detected. The resulting enzyme activities may be characteristic of a specific disorder; however, abnormal results require confirmation by additional biochemical or molecular genetic analysis.

 

When abnormal results are detected, a detailed interpretation is given, including an overview of results and significance, a correlation to available clinical information, elements of differential diagnosis, and recommendations for additional confirmatory studies (enzyme assay, molecular genetic analysis).

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

The test can give false-negative results, especially in older patients with mild clinical presentations. 

 

Additional biochemical or molecular genetic analysis is required to confirm a suspected diagnosis.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

An interpretive report will be provided.

Clinical References Provides recommendations for further in-depth reading of a clinical nature

Part 16: Lysosomal Disorders. In Scriver's The Online Metabolic and Molecular Bases of Inherited Disease (OMMBID). Edited by D Valle, AL Beaudet, B Vogelstein, et al. McGraw-Hill Medical Division. Accessed 3/23/2016. Available at http://ommbid.mhmedical.com/book.aspx?bookid=971

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