X-linked recessive Menkes disease: carrier detection in the case of a partial gene deletion.

Abstract

X-linked recessive Menkes disease is a lethal disorder of copper metabolism, caused by defects in the ATP7A gene. About 15% of the mutations causing Menkes disease are partial gene deletions. We have previously demonstrated carrier diagnosis of deletions in heterozygotes by Southern blot analysis. As this technique is very time-consuming alternative methods are obviously of high value. Multiplex polymerase chain reaction (PCR), reverse transcription PCR (RT-PCR) and spanning the deletion on genomic DNA can all be used for detection of partial gene deletions in male patients, but only spanning of the deletion can be applied for carrier detection. Simple multiplex PCR is not applicable for carrier detection because the normal allele of ATP7A will be PCR amplified thus masking the deletion. Here, we demonstrate, in addition to spanning of the deletion on genomic DNA, carrier detection based on the use of a previously unrecognized polymorphism in intron 13 of ATP7A in combination with previously identified intragenic polymorphic markers. We show that these intragenic markers can be used for carrier detection, not only indirectly by determining segregation of the disease related allele but also directly if located within the deleted region. We demonstrate determination of the carrier status of 21 at-risk carriers.