GENOTYPE AND PHENOTYPE IN PATIENTS WITH MENKES DISEASE AND OCCIPITAL HORN SYNDROME

Kodama H, Gu YH, Murata Y, Mochizuki D, Shiga K, Mori Y, Yanagawa Y, Kaji M

Dept of Pediatrics, Teikyo University School of Medicine, Tokyo, Japan

 

Objective: Menkes disease (MNK) and occipital horn syndrome (OHS) are caused by the defect in a copper transporting ATPase (ATP7A). OHS is a milder phenotype of MNK to clarify the difference of phenotypes between MNK and OHS.

Methods: Genomic DNA of 16 patients with classical MNK and one patient with OHS were studies for mutations in the ATP7A gene. RT-PCR analysis was also performed using either cultured fibroblasts or lymphoblasts transformed by EB virus. Quantitative RT-PCR of ATP7A m RNA was performed using fibroblasts from the patient with OHS and real-time Taqman TM tedhnology.

Results: We identified 16 mutationsin patients with MNK, including 4 deletions, 2 insertions, 6 nonsence mutations, 2 missence mutations and 2 splice site mutations. The mutation in the OHS occurred at the splice site in intron 6, leading to skipping of exon 6. RT-PCR revealed that the splice site mutation in 2 patients with MNK produced shorter transcripts, with no transcripts in the normal position; while the splice site mutation in the patient with OHS produced two transcripts, one is normal size and the other is smaller. The amount of the normal-size transcript in the cultured fibroblasts from the OHS patient wree 19% of the normal level, suggesting clinical manifestations of OHA are due to the presence of normal-size and presumably functional transcript of the ATP7A gene.

Conclusion: We identified 16 mutations in the patients with MNK and a splice site mutation in a patient with OHS. The mutation found in the OHS patient produced two transcripts, one is normal size and the other smaller. The amount of the normal-size transcript was 19% of the normal level.

 
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