Authors: Yoko Kawai Akihiko Moriyama Kiyofumi Asai Carrie M ColemanCampbell Satoshi Sumi Hideko Morishita Mariko Suchi
Publish Date: 2005/01/27
Volume: 116, Issue: 5, Pages: 340-346
Abstract
Histidinemia MIM235800 is characterized by elevated histidine in body fluids and decreased urocanic acid in blood and skin and results from histidase histidine ammonia lyase EC 4313 deficiency It is the most frequent inborn metabolic error in Japan Although the original description included mental retardation and speech impairment neonatal screening programs have identified the majority of histidinemic patients with normal intelligence Molecular characteristics of histidase in histidinemia have not been determined and cytogenetically visible deletions of 12q22241 in which histidase gene resides have not been identified in histidinemic patients In order to investigate whether individuals with this disorder have small deletions additions or point mutations in the histidase gene we screened genomic DNA isolated from 50 histidinemic individuals who were discovered by the neonatal screening program The methods employed included polymerase chain reaction PCR amplification of exons 1–21 of the histidase gene followed by mutation detection enhancement gel electrophoresis and sequencing of the PCR products displaying heteroduplex bands Four missense mutations R322P P259L R206T and R208L two exonic polymorphisms T141T c423A→T and P259P c777A→G and two intronic polymorphisms IVS6−5T→C and IVS9+25A→G were identified The frequencies of each polymorphism estimated either by dot blot allelespecific oligonucleotide hybridization restriction enzyme digestion or direct sequencing of the PCR products amplified from 50 unrelated normal individuals were 028 030 040 and less than 001 respectively Mutation analysis of one family demonstrated that the patient inherited R322P from the mother and P259L from the father This report describes the first mutations occurring in the coding region of the histidase structural gene in patients with histidinemiaWe thank the late Dr Taiji Kato for graciously providing access to his laboratory facilities in the Department of Molecular Neurobiology Drs Yoshiro Wada and Hisako Saito for their seminal work and continuous encouragement Dr Haruo Mizuno for the preparation of genomic DNA from normal individuals and Manami Yamamoto for her technical assistance We are also grateful to physicians in the Department of Pediatrics Neonatology and Congenital Disorders Nagoya City University for the care of the patients and to laboratory staff members of the General Clinical Research Center The Children’s Hospital of Philadelphia for their technical support This study was supported in part by a Research Grant from the Ministry of Health Labor and Welfare of Japan and NIH/NRCC grant M01RR00240
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