Objawy okulistyczne i diagnostyka pacjenta z chorobą Janskiego-Bielszowskiego (CLN2)

Introduction
Type 2 neuronal ceroid lipofuscinosis (CLN2) is a rare lysosomal neurodegenerative disease in which ceroid accumulating mainly in nerve cells. The disease manifests itself in the first years of a child’s life as convulsions, epilepsy, gradual deterioration of motor function with gradual visual acuity impairment.

Case report
In a five-year-old patient with divergent squint, nystagmus, epilepsy confirmed in EEG and with significance decrease in visual acuity, ophthalmological examinations confirmed at irregular, re-arrangement of dye, covering the macular region indicating the presence of the bull’s eye maculopathy. Additional changes were features of pallor of optic nerve disc with generalized retinal vessels vasoconstriction. In electrophysiological tests of fERG, damage of the bioelectrophysiological function of the retina indicating cone-rod like degeneration was recorded. In lab tests, reduction of lysosomal enzyme activity – tripeptidyl peptidase (TPP1) in leukocytes (CLN2) 0.7 U/mg of protein/h (corrected level: 54 ±18.2 U/mg of protein/h) was observed. Other metabolic, mitochondrial and mucopolysaccharidosis conditions have been excluded. The diagnosis was supplemented by numerous atrophic changes inside the brain, cerebellum, and widening of the central nervous system (CNS) ventricular spaces described in MRI.

Conclusions
An important element of the early diagnosis of CLN2 is the reduction of TPP1 activity with the characteristic eye fundus image that indicates the presence of buffalo maculopathy. An inseparable complement to the diagnosis of CLN2 is the fERG test indicating lesions of the rod-cone like system that underlie visual disturbances.