Enzyme based diagnosis of type 1 and 2 neuronal ceroid lipofuscinoses

Radwan, Amira; Fateen, Ekram; Gouda, Amr; Zaki, Maha; Ali, Ola

doi:10.21608/aijpms.2021.60825.1044

Enzyme based diagnosis of type 1 and 2 neuronal ceroid lipofuscinoses

Document Type : Original research articles

Authors

¹ Department of Biochemical Genetics, Human Genetics and Genome Research Division, Center of Excellence of Human Genetics, National Research Centre, Giza, Egypt

² Clinical Genetics Department, Human Genetics and Genome Research Division, Center of Excellence of Human Genetics, National Research Centre, Giza, Egypt

³ Department of Biochemistry, Faculty of Pharmacy (Girls), Al-Azhar University, Cairo, Egypt

10.21608/aijpms.2021.60825.1044

Abstract

The study aimed to diagnose type 1 and 2 of neuronal ceroid lipofuscinoses (NCLs) using leukocytes and dried blood spot samples. A hundred subjects divided equally to patient and control groups of matching age and sex were included. The patient group was subclassified into two subgroups according to age. Measurement of palmitoyl protein thioesterase1 (PPT1) and tripeptidyl peptidase1 (TPP1) enzymes were conducted in both leukocytes and dried blood spot samples. Chitotriosidase enzyme activity was measured in plasma samples and was found to be normal in 10 cases and increased in 2 cases. Based on PPT1 and TPP1 enzymes activity, 12 cases were diagnosed from the 50 investigated patients and distributed equally between the 2 types. In cases with NCL 1, the Mean ± SD PPT1enzyme activity was decreased to 0.02 ± 0.0074 nmol/h/mg protein in leukocytes samples when compared to 3.4 ± 2.5 nmol/h /mg protein in controls while the activity was decreased to 0.063±0.09 nmol/spot in dried blood spot samples when compared to 0.88±0.32 nmol/spot in controls. In cases, with NCL2 the Mean ± SD TPP1 enzyme activity was decreased to 0.023±0.014 nmol/h/mg protein in leukocytes when compared to 0.92±0.84 nmol/h /mg protein in controls. While the activity was decreased to 0.04±0.035 nmol/spot in dried blood spot samples when compared to 0.394±0.17 nmol/spot in controls. The study concluded that dried blood spot sample method is satisfactory for confirming or excluding suspected patients while leukocyte samples are needed to confirm the positive or unclear results.

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