A new simple enzyme assay for pre- and postnatal diagnosis of infantile neuronal ceroid lipofuscinosis (INCL) and its variants
- Y V Voznyia,
- J L M Keulemansb,
- G M S Mancinib,
- C E Catsman-Berrevoetsc,
- E Youngd,
- B Winchesterd,
- W J Kleijerb,
- O P van Diggelenb
- aInstitute of Organic Chemistry, Moscow, Russia, bDepartment of Clinical Genetics, University Hospital, Erasmus University, PO Box 1738, 3000 DR Rotterdam, The Netherlands, cDepartment of Child Neurology, University Hospital, Erasmus University, Rotterdam, The Netherlands, dInstitute of Child Health, London, UK
- Dr van Diggelen.
- Received 13 August 1998
- Revised 15 December 1998
Abstract
Palmitoyl-protein thioesterase (PPT) deficiency was recently shown to be the primary defect in infantile neuronal ceroid lipofuscinosis (INCL). The available enzyme assay is complicated and impractical for diagnostic use and is, in practice, unavailable. We have developed a new fluorimetric assay for PPT based on the sensitive fluorochrome 4-methylumbelliferone. This PPT assay is simple, sensitive, and robust and will facilitate the definition of the full clinical spectrum associated with a deficiency of PPT. PPT activity was readily detectable in fibroblasts, leucocytes, lymphoblasts, amniotic fluid cells, and chorionic villi, but was profoundly deficient in these tissues from INCL patients. Similarly, a deficiency of PPT was shown in patients with the variant juvenile NCL with GROD. These results show that rapid pre- and postnatal diagnosis can be performed with this new enzyme assay for PPT.
