Lysosomal glycogen storage disease with normal acid maltase (Danon) is caus
ed by primary lysosome-associated membrane protein-2 (LAMP-2) deficiency. T
ypically, the disease begins after the first decade; however, two infantile
patients had similar histologic features. The infantile disorder is distin
ct from Danon disease, because, in both infants, LAMP-2 protein is present
in skeletal muscle. Deposition of C5b-9 and multilayered basal lamina in on
e patient suggest that the infantile disease is pathogenically similar to X
-linked myopathy with excessive autophagy.