Low function of natural killer cells in treated classic Menkes disease

BACKGROUND: Menkes disease (MD) is a rare lethal X-linked, multisystem disorder of copper metabolism resulting from mutations in the ATP7A gene. Features such as Ehlers- Danlos syndrome, trichopoliodystrophy, urologic and skeletal changes have been reported. We present a case of classic MD treated with copper infusions who suffered from persistent natural killer (NK) cell dysfunction. CASE: A 2-year-old, Caucasian male child presented at 8-month-old of age with persistent hypotonia, kinky hair and developmental regression. Diagnosis of MD was based on low serum levels of copper [5 mg/dl (18-37)] and ceruloplasmin [18 ug/dl (75-153)] and gene-targeted deletion/duplication analysis performed by the reference laboratory. Brain MRI showed mild hypoplasia of the cerebellar vermis and vascular tortuosity typical of MD. Copper chloride treatment was immediately initiated. The child became more alert with excellent eye contact and purposeful movements. The child was hospitalized for recurrent respiratory infections, each time caused by enterovirus as confirmed by multiplex polymerase chain reaction (PCR). Extensive immunologic studies were negative, except for a severe NK cell dysfunction on multiple occasions (0.6 NK lytic Units; N > 2.6). CONCLUSION: We postulate that NK cell dysfunction in a classic MD can be explained by the deficient incorporation of copper in the endoplasmic reticulum resulting in an abnormal Fenton chemistry within phagosomes.