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Expanding the clinical and molecular characteristics of PIGT-CDG, a disorder of glycosylphosphatidylinositol anchors

Overview of attention for article published in Molecular Genetics & Metabolism, May 2015
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Title
Expanding the clinical and molecular characteristics of PIGT-CDG, a disorder of glycosylphosphatidylinositol anchors
Published in
Molecular Genetics & Metabolism, May 2015
DOI 10.1016/j.ymgme.2015.04.007
Pubmed ID
Authors

Christina Lam, Gretchen A. Golas, Mariska Davids, Marjan Huizing, Megan S. Kane, Donna M. Krasnewich, May Christine V. Malicdan, David R. Adams, Thomas C. Markello, Wadih M. Zein, Andrea L. Gropman, Maya B. Lodish, Constantine A. Stratakis, Irina Maric, Sergio D. Rosenzweig, Eva H. Baker, Carlos R. Ferreira, Noelle R. Danylchuk, Stephen Kahler, Adolfo D. Garnica, G. Bradley Schaefer, Cornelius F. Boerkoel, William A. Gahl, Lynne A. Wolfe

Abstract

PIGT-CDG, an autosomal recessive syndromic intellectual disability disorder of glycosylphosphatidylinositol (GPI) anchors, was recently described in two independent kindreds [Multiple Congenital Anomalies-Hypotonia-Seizures Syndrome 3 (OMIM, #615398)]. PIGT encodes phosphatidylinositol-glycan biosynthesis class T, a subunit of the heteropentameric transamidase complex that facilitates the transfer of GPI to proteins. GPI facilitates attachment (anchoring) of proteins to cell membranes. We describe, at ages 7 and 6years, two children of non-consanguineous parents; they had hypotonia, severe global developmental delay, and intractable seizures along with endocrine, ophthalmologic, skeletal, hearing, and cardiac anomalies. Exome sequencing revealed that both siblings had compound heterozygous variants in PIGT (NM_015937.5), i.e., c.918dupC, a novel duplication leading to a frameshift, and c.1342C>T encoding a previously described missense variant. Flow cytometry studies showed decreased surface expression of GPI-anchored proteins on granulocytes, consistent with findings in previous cases. These siblings further delineate the clinical spectrum of PIGT-CDG, reemphasize the neuro-ophthalmologic presentation, clarify the endocrine features, and add hypermobility, low CSF albumin quotient, and hearing loss to the phenotypic spectrum. Our results emphasize that GPI anchor-related congenital disorders of glycosylation (CDGs) should be considered in subjects with early onset severe seizure disorders and dysmorphic facial features, even in the presence of a normal carbohydrate-deficient transferrin pattern and N-glycan profiling. Currently available screening for CDGs will not reliably detect this family of disorders, and our case reaffirms that the use of flow cytometry and genetic testing is essential for diagnosis in this group of disorders.

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Mendeley readers

The data shown below were compiled from readership statistics for 64 Mendeley readers of this research output. Click here to see the associated Mendeley record.

Geographical breakdown

Country Count As %
Denmark 1 2%
Unknown 63 98%

Demographic breakdown

Readers by professional status Count As %
Student > Ph. D. Student 11 17%
Other 9 14%
Student > Master 7 11%
Researcher 5 8%
Student > Bachelor 4 6%
Other 16 25%
Unknown 12 19%
Readers by discipline Count As %
Medicine and Dentistry 16 25%
Nursing and Health Professions 7 11%
Psychology 6 9%
Biochemistry, Genetics and Molecular Biology 6 9%
Agricultural and Biological Sciences 5 8%
Other 9 14%
Unknown 15 23%