beta-trace protein in human cerebrospinal fluid: a diagnostic marker for N-glycosylation defects in brain

As carbohydrate-deficient glycoprotein syndromes (CDGS) are multisystemic d isorders with impaired central nervous function in nearly all cases, we tes ted isoforms of beta-trace protein (beta TP), a 'brain-type' glycosylated p rotein in cerebrospinal fluid (CSF) of nine patients with the characteristi c CDGS type I pattern of serum transferrin. Whereas the serum transferrin p attern did not discriminate between the various subtypes of CDGS type I (CD GS type Ia, type Ic and patients with unknown defect), beta TP isoforms of CDGS type Ia patients differed from that of the other CDGS type I patients. The percentage of abnormal beta TP isoforms correlated with the severity o f the neurological symptoms. Furthermore, two patients are described, who i llustrate that abnormal protein N-glycosylation can occur restricted to eit her the 'peripheral' serum or the central nervous system compartment. This is the first report presenting evidence for an N-glycosylation defect restr icted to the brain. Testing PTP isoforms is a useful tool to detect protein N-glycosylation disorders in the central nervous system. (C) 1999 Elsevier Science B.V. All rights reserved.