Rapid, accurate and comprehensive diagnostic method for the detection of Neuronal Ceroid Lipofuscinosis Type 2 (CLN2) Disease using long-read third-generation sequencing technology

Creative Commons License

Teker B., Tatonyan S., Balcı M. C., Karaca M., Akan G., Özgen Ö., ...Daha Fazla

SSIEM Annual Symposium 2023, Tel-Aviv-Yafo, İsrail, 29 Ağustos - 01 Eylül 2023, cilt.46, sa.686, ss.361

  • Yayın Türü: Bildiri / Özet Bildiri
  • Cilt numarası: 46
  • Basıldığı Şehir: Tel-Aviv-Yafo
  • Basıldığı Ülke: İsrail
  • Sayfa Sayıları: ss.361
  • İstanbul Üniversitesi Adresli: Evet

Özet

Neuronal Ceroid Lipofuscinosis Type II (CLN2) disease, a subtype of NCL, is an autosomal recessive, severe neurodegenerative lysosomal storage disease caused by mutations in the lysosomal tripeptidyl peptidase 1 (TPP1/CLN2) gene. Early diagnosis is important to optimize clinical care and improve outcomes. Cerliponase alfa, the recombinant human TPP1, is the first and recently approved enzyme replacement therapy for the treatment of CLN2 disease. CLN2 disease can be diagnosed through clinical findings, detection of TPP1 enzyme deficiency, and/or mutations in the TPP1 gene. With aim of achieving a rapid molecular diagnosis, we optimized our workflow for targeted long-read thirdgeneration sequencing of the TPP1/CLN2 gene. We also determined TPP1 enzyme activities of the study population. Methods: 23 individuals were included in the study. TPP1 enzyme activity was measured fluorometrically and we sequenced the entire CLN2 genomic region (6655bp., 13 exon, 12 intron, 3’ and 5’UTR) via 5 overlapping fragments covering 6846 bases, using targeted long-read third-generation sequencing technology. Results: We detected 3 different pathogenic variants in all seven index cases; one being homozygous for the missense c.857AG (p.Asn286Ser) variant. We also characterized stop mutations in two patients carrying c.1204GT (p.Glu402Ter) and four patients carrying c.622CT (p.Arg208Ter). We also detected a frameshift deletion variant (not reported in ClinVar) in four patients carrying c.1537del (p.Ala513GlnInfsTer6). Moreover, 2 likely pathogenic, 4 VUS (variants of uncertain significance), and 10 benign variants were identified in the whole study population. Enzyme analysis also confirmed the disease states of the index cases.

Conclusion: Targeted long-read third-generation sequencing technologies will provide a game-changing advantage for achieving a rapid, accurate, and comprehensive molecular diagnosis in order to start the needed treatments as early as possible.