The spectrum of mutations in the PCFT gene, coding for an intestinal folate transporter, that are the basis for hereditary folate malabsorption.
Hereditary folate malabsorption (HFM) is a rare autosomal recessive disorder caused by impaired intestinal folate absorption and impaired folate transport into the central nervous system. Recent studies in 1 family revealed that the molecular basis for this disorder is a loss-of-function mutation in the PCFT gene encoding a proton-coupled folate transporter. The current study broadens the understanding of the spectrum of alterations in the PCFT gene associated with HFM in 5 additional patients. There was no racial, ethnic, or sex pattern. A total of 4 different homozygous mutations were detected in 4 patients; 2 heterozygous mutations were identified in the fifth patient. Mutations involved 4 of the 5 exons, all at highly conserved amino acid residues. A total of 4 of the mutated transporters resulted in a complete loss of transport function, primarily due to decreased protein stability and/or defects in membrane trafficking, while 2 of the mutated carriers manifested residual function. Folate transport at low pH was markedly impaired in transformed lymphocytes from 2 patients. These findings further substantiate the role that mutations in PCFT play in the pathogenesis of HFM and will make possible rapid diagnosis and treatment of this disorder in infants, and prenatal diagnosis in families that carry a mutated gene.
Zhao
Rongbao
R
Departments of Medicine, Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Min
Sang Hee
SH
Qiu
Andong
A
Sakaris
Antoinette
A
Goldberg
Gary L
GL
Sandoval
Claudio
C
Malatack
J Jeffrey
JJ
Rosenblatt
David S
DS
Goldman
I David
ID
D000595:Amino Acid Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D016022:Case-Control Studies; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D005260:Female; D005455:Fluorescent Antibody Technique; D005492:Folic Acid / Q000378:metabolism*; D006367:HeLa Cells; D006579:Heterozygote; D006801:Humans; D007223:Infant; D007413:Intestinal Mucosa / Q000378:metabolism; D008214:Lymphocytes / Q000187:drug effects / Q000378:metabolism; D008286:Malabsorption Syndromes / Q000235:genetics*; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010375:Pedigree; D016133:Polymerase Chain Reaction; D058979:Proton-Coupled Folate Transporter
D026901:Membrane Transport Proteins; D058979:Proton-Coupled Folate Transporter; C505058:SLC46A1 protein, human; D005492:Folic Acid