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A homozygous variant disrupting the PIGH start-codon is associated with developmental delay, epilepsy, and microcephaly.

Published version
Peer-reviewed

Type

Article

Change log

Authors

Pagnamenta, Alistair T  ORCID logo  https://orcid.org/0000-0001-7334-0602
Anzilotti, Consuelo 
Titheradge, Hannah 
Oates, Adam J 

Abstract

Defective glycosylphosphatidylinositol (GPI)-anchor biogenesis can cause a spectrum of predominantly neurological problems. For eight genes critical to this biological process, disease associations are not yet reported. Scanning exomes from 7,833 parent-child trios and 1,792 singletons from the DDD study for biallelic variants in this gene-set uncovered a rare PIGH variant in a boy with epilepsy, microcephaly, and behavioral difficulties. Although only 2/2 reads harbored this c.1A > T transversion, the presence of ∼25 Mb autozygosity at this locus implied homozygosity, which was confirmed using Sanger sequencing. A similarly-affected sister was also homozygous. FACS analysis of PIGH-deficient CHO cells indicated that cDNAs with c.1A > T could not efficiently restore expression of GPI-APs. Truncation of PIGH protein was consistent with the utilization of an in-frame start-site at codon 63. In summary, we describe siblings harboring a homozygous c.1A > T variant resulting in defective GPI-anchor biogenesis and highlight the importance of exploring low-coverage variants within autozygous regions.

Description

Keywords

GPI-anchor biogenesis, PIGH, developmental delay, exome, microcephaly, phosphatidylinositol N-acetylglucosaminyltransferase, Adolescent, Animals, Child, Child, Preschool, Codon, Initiator, Cricetinae, Developmental Disabilities, Epilepsy, Exome, Female, Glycosylphosphatidylinositols, Humans, Male, Membrane Proteins, Microcephaly, Mutation, Pedigree

Journal Title

Hum Mutat

Conference Name

Journal ISSN

1059-7794
1098-1004

Volume Title

39

Publisher

Hindawi Limited