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.