Hypomorphic promoter mutation in PIGM causes inherited glycosylphosphatidylinositol deficiency.
Attachment to the plasma membrane by linkage to a glycosylphosphatidylinositol (GPI) anchor is a mode of protein expression highly conserved from protozoa to mammals. As a clinical entity, deficiency of GPI has been recognized as paroxysmal nocturnal hemoglobinuria, an acquired clonal disorder associated with somatic mutations of the X-linked PIGA gene in hematopoietic cells. We have identified a novel disease characterized by a propensity to venous thrombosis and seizures in which deficiency of GPI is inherited in an autosomal recessive manner. In two unrelated kindreds, a point mutation (c --> g) at position -270 from the start codon of PIGM, a mannosyltransferase-encoding gene, disrupts binding of the transcription factor Sp1 to its cognate promoter motif. This mutation substantially reduces transcription of PIGM and blocks mannosylation of GPI, leading to partial but severe deficiency of GPI. These findings indicate that biosynthesis of GPI is essential to maintain homeostasis of blood coagulation and neurological function.
Almeida
Antonio M
AM
Department of Haematology, Imperial College London, Hammersmith Hospital, Du Cane Road, London, W12, 0NN, UK.
Murakami
Yoshiko
Y
Layton
D Mark
DM
Hillmen
Peter
P
Sellick
Gabrielle S
GS
Maeda
Yusuke
Y
Richards
Stephen
S
Patterson
Scott
S
Kotsianidis
Ioannis
I
Mollica
Luigina
L
Crawford
Dorothy H
DH
Baker
Alastair
A
Ferguson
Michael
M
Roberts
Irene
I
Houlston
Richard
R
Kinoshita
Taroh
T
Karadimitris
Anastasios
A
D000595:Amino Acid Sequence; D001483:Base Sequence; D005260:Female; D005808:Genes, Recessive; D017261:Glycosylphosphatidylinositols / Q000172:deficiency*; D006456:Hemoglobinuria / Q000235:genetics; D006801:Humans; D008297:Male; D008364:Mannosyltransferases / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D010375:Pedigree; D011401:Promoter Regions, Genetic; D012640:Seizures / Q000235:genetics; D013927:Thrombosis / Q000235:genetics
D017261:Glycosylphosphatidylinositols; D008364:Mannosyltransferases; C486036:PIGM protein, human