PIGT-CDG, a disorder of the glycosylphosphatidylinositol anchor: description of 13 novel patients and expansion of the clinical characteristics

Allan Bayat*, Alexej Knaus, Annika Wollenberg Juul, Dejan Dukic, Elena Gardella, Agnieszka Charzewska, Emma Clement, Helle Hjalgrim, Dorota Hoffman-Zacharska, Denise Horn, Rachel Horton, Jane A. Hurst, Dragana Josifova, Line H.G. Larsen, Karine Lascelles, Ewa Obersztyn, Alistair Pagnamenta, Deb K. Pal, Manuela Pendziwiat, Mina RytenJenny Taylor, Julie Vogt, Yvonne Weber, Peter M. Krawitz, Ingo Helbig, Usha Kini, Rikke S. Møller, the DDD Study Group

*Corresponding author for this work

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Abstract

Purpose: To provide a detailed electroclinical description and expand the phenotype of PIGT-CDG, to perform genotype–phenotype correlation, and to investigate the onset and severity of the epilepsy associated with the different genetic subtypes of this rare disorder. Furthermore, to use computer-assisted facial gestalt analysis in PIGT-CDG and to the compare findings with other glycosylphosphatidylinositol (GPI) anchor deficiencies. Methods: We evaluated 13 children from eight unrelated families with homozygous or compound heterozygous pathogenic variants in PIGT. Results: All patients had hypotonia, severe developmental delay, and epilepsy. Epilepsy onset ranged from first day of life to two years of age. Severity of the seizure disorder varied from treatable seizures to severe neonatal onset epileptic encephalopathies. The facial gestalt of patients resembled that of previously published PIGT patients as they were closest to the center of the PIGT cluster in the clinical face phenotype space and were distinguishable from other gene-specific phenotypes. Conclusion: We expand our knowledge of PIGT. Our cases reaffirm that the use of genetic testing is essential for diagnosis in this group of disorders. Finally, we show that computer-assisted facial gestalt analysis accurately assigned PIGT cases to the multiple congenital anomalies–hypotonia–seizures syndrome phenotypic series advocating the additional use of next-generation phenotyping technology.

Original languageEnglish
JournalGenetics in Medicine
Volume21
Issue number10
Pages (from-to)2216-2223
ISSN1098-3600
DOIs
Publication statusPublished - Oct 2019

Keywords

  • computer-assisted facial gestalt analysis
  • congenital disorder of glycosylation
  • epilepsy
  • genotype–phenotype
  • PIGT-CDG

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