Draw blood in a yellow-top (ACD) tube. Preferred Minimum: 7 mL of ACD whole blood Absolute Minimum: 5 mL of ACD whole blood

The amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected. Please refer to the Lysosomal Storage Disorders for further information.

TPP1: 85-326 nmol/hr/mg protein PPT1: 20-93 nmol/hr/mg protein

Useful for evaluation of patients with clinical presentations suggestive of NCL and an aid in the differential diagnosis of infantile and late infantile NCL. Cautions: This assay does not detect carrier status of NCL. Some variants with an age of onset occurring in older individuals have been noted. Neuronal ceroid lipofuscinoses (NCL) are inherited neurodegenerative disorders with an overall incidence in the United States estimated at1:12,500. Clinically they are characterized by vision loss, seizures, mental regression, behavioral changes, movement disorders, and the accumulation of storage material with a characteristic appearance by electron microscopy (EM). Tissue damage is selective for the nervous system and many patients succumb in the first decade of life due to central nervous system degeneration. The infantile NCL form is caused by deficiency of the lysosomal enzyme palmitoyl-protein thioesterase 1 (PPT1), which cleaves a thioester linkage between a fatty acid (palmitate) and cysteine in lipid-modified proteins. It is an early onset disease characterized by psychomotor degeneration, seizures, and progressive macular degeneration leading to blindness by the age of 2. Infantile NCL is an autosomal recessive disorder with an incidence of 1:20,000 in Finland and rare elsewhere. The late infantile form of NCL is caused by deficiency of the lysosomal enzyme tripeptidyl peptidase 1 (TPP1), which cleaves tripeptides from the N-terminus of polypeptides. Tissue damages are especially neuronal, resulting from the defective degradation and consequent lysosomal storage of small peptides. Disease onset occurs at 2 to 4 years of age with death occurring around the age of 10.