Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

FFTRP
91774
thioesterase 1 (PPT1), which cleaves long-chain fatty acids (usually palmitate) from cysteine residues.
Electron microscopy shows granular osmophilic deposits (GRODs) in most cell types. PPT1 is thought to
play an active role in various cell processes including apoptosis, endocytosis, and lipid metabolism.
Infantile NCL has an incidence of 1 in 20,000 in Finland and is rare elsewhere. The late infantile form of
NCL (CLN2) is caused by deficiency of the lysosomal enzyme tripeptidyl peptidase 1 (TPP1), which
cleaves tripeptides from the N-terminus of polypeptides. Tissue damage results from the defective
degradation and consequent accumulation of storage material with a curvilinear profile by electron
microscopy. There is widespread loss of neuronal tissue especially in the cerebellum and hippocampal
region. Disease onset occurs at 2 to 4 years of age with seizures, ataxia, myoclonus, psychomotor
retardation, vision loss and speech impairment. Diagnostic strategy depends on the age of onset of
symptoms. In children presenting between the ages 0 to 4 years, enzyme assay of PPT1 and TPP1 is an
appropriate first step. In addition, molecular genetic testing of CLN1 or CLN2 may allow for
identification of the disease causing mutations.
Useful For: Evaluation of patients with clinical presentations suggestive of neuronal ceroid
lipofuscinoses (NCL) An aid in the differential diagnosis of infantile and late infantile NCL
Interpretation: Tripeptidyl peptidase 1 (TPP1) and palmitoyl-protein thioesterase 1 (PPT1) enzyme
activity below 5 nmol/hour/mg of protein are highly suggestive of late-infantile and infantile neuronal
ceroid lipofuscinoses, respectively.
Reference Values:
TPP1: 85-326 nmol/hour/mg protein
PPT1: 20-93 nmol/hour/mg protein
Clinical References: 1. Haltia M: The neuronal ceroid-lipofuscinoses: from past to present.
Biochim Biophys Acta 2006;1762:850-856 2. Kavianen R: Juvenile-onset neuronal ceroid
lipofuscinosis with infantile CLN1 mutation and palmitoyl-protein thioesterase deficiency. Eur J Neur
2007;14:369-372 3. Enns GM, Steiner RD, Cowan TM: Lysosomal disorders. In Pediatric
Endocrinology and Inborn Errors of Metabolism. Edited by K Sarafoglou, GF Hoffmann, KS Roth,
New York, McGraw-Hill Medical Division, 2009, pp 749-750
Trofile Co-Receptor Tropism Assay
Useful For: Phenotypic determination of the type of co-receptor used by patientâ€s HIV-1 strain to
enter host CD4+ cells (HIV-1 entry co-receptor tropism).
Reference Values:
TROFILE VIRAL CLASSIFICATION
CCR5 Tropic (R5) HIV-1
Virus uses CCR5 to enter CD4+ cells.
CXCR4 Tropic (X4) HIV-1
Virus uses CXCR4 to enter CD4+ cells.
DUAL /MIXED Tropic (D/M) HIV-1
Dual-tropic viruses can use either CCR5 or CXCR4 to enter
CD4+ cells. Mixed-tropic populations contain viruses with two
or more tropisms.
Non-reportable
Co-receptor tropism could not be determined by the Trofile
assay. Common causes of a non-reportable result are viral load