| Web: | mayocliniclabs.com |
|---|---|
| Email: | mcl@mayo.edu |
| Telephone: | 800-533-1710 |
| International: | +1 855-379-3115 |
| Values are valid only on day of printing | |
| Web: | mayocliniclabs.com |
|---|---|
| Email: | mcl@mayo.edu |
| Telephone: | 800-533-1710 |
| International: | +1 855-379-3115 |
| Values are valid only on day of printing | |
Congenital disorders of glycosylation (CDG), galactosemias, and glycogen storage disorders (GSD) are rare conditions caused by deficiencies in the body’s ability to utilize or metabolize carbohydrates.
Obtaining early and accurate diagnosis is essential for guiding treatment and management decisions and for accurate genetic counseling. Our robust portfolio of biochemical and molecular genetic assays can identify genetic variants and confirm the diagnosis of the specific disorder. In addition, molecular genetic testing for all of the disorders of carbohydrate metabolism presented here, and many others not included in pre-existing panels, is available through our custom gene ordering tool.
Carbohydrate metabolism test menu
Congenital disorders of glycosylation are a group of more than 130 rare genetic disorders1 that can be caused by a broad range of defects in the assembly, processing, and trafficking of glycoproteins and glycolipids. These disorders present with nonspecific, multi-systemic features and considerable variation in severity, ranging from nearly normal to lethal multi-organ dysfunction.
We offer glycan analysis, enzyme testing, and molecular genetic testing options to diagnose and monitor patients with CDG. Our testing combinations are not offered by any other laboratory and make use of tandem mass spectrometry (MS/MS) assays of blood specimens and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis of blood and urine specimens.
Use of these platforms allows us to detect more than 50 CDG types. For CDG disorders not detectable by these methods, our comprehensive gene panel includes sequencing, deletion/duplication studies, and analysis of intronic disease-causing alterations in currently 141 CDG-associated genes.
Biochemical testing
Molecular testing
Highlights
In this month’s “Hot Topic,” Gessi Pino, a genetic counselor in the Biochemical Genetics Lab at Mayo Clinic, and Kimiyo Raymond, M.D., a clinical consultant in the laboratory and an expert in Congenital Disorders of Glycosylation (CDG), discuss glycosylation and its importance in human biology, highlight laboratory testing, and offer strategies to screen and diagnose CDGs.
Galactosemia occurs where there is a deficiency of any one of the four enzymes catalyzing the conversion of galactose to glucose: galactose mutarotase (GALM), galactokinase (GALK), galactose-1-phosphate uridyltransferase (GALT), and uridine diphosphate galactose-4-epimerase (GALE). Classic galactosemia, GALT, is the most common form of galactosemia. In affected newborns, uptake of galactose causes a toxic build-up and is life-threatening if untreated, with complications including failure to thrive, liver failure, and (E-coli) sepsis.
Diagnosis of classic galactosemia is through the detection of an elevated concentration of galactose-1-phosphate, reduced GALT enzyme activity, and/or biallelic pathogenic variants in GALT.2 Our comprehensive test menu of biochemical and molecular genetic assays, including custom gene testing for the rarer forms of galactosemia, GALK, GALE, and GALM, can provide diagnostic and prognostic insights.
Reflex testing
Biochemical testing
Molecular testing
Glycogen storage diseases (GSD) are a group of inherited metabolic conditions caused by a deficiency of enzymes responsible for glycogen metabolism. Resulting in abnormal storage of glycogen in the liver and various muscles, symptoms and severity are variable and dependent on the specific GSD.
Preliminary testing including glucose monitoring, triglycerides, uric acid, creatine kinase, liver function tests, and complete blood cell count can be helpful in suggesting a diagnosis of GSD. Our specialized enzyme, biomarker, and molecular genetic test offerings can provide diagnostic clarity for affected patients and their family members.
Biochemical testing
Molecular testing
Extremely rare, transaldolase (TALDO) and ribose-5-phosphate (RPI) deficiencies have only been reported in a few individuals but result in serious medical complications. Linked to genetic variation, the deficiencies require genetic testing to confirm diagnosis.
Biochemical testing
Our custom gene ordering allows the creation of a custom gene list to tailor molecular genetic testing to a patient’s exact need. After selection of the Inborn Errors of Metabolism disease state, the custom gene panel can be modified to add or remove genes. Through this option, single-gene testing or a custom gene panel can be performed.
Key testing