Barth syndrome is an X-linked disorder characterised by cardioskeletal myopathy 
of variable severity usually fatal in childhood, and neutropenia. We ascertained 
a large pedigree with affected males in 3 generations. All affected males had 
dilated cardiomyopathy, with endocardial fibroelastosis (EFE) in some. The locus 
for Barth syndrome in this family was found to be closely linked to DXS52 (z = 
2.78, theta = 0.0). The family was nonrecombinant for DXS52 in distal Xq28, but 
recombinant for DXS374 which maps proximal to DXS52. This localised Barth 
syndrome distal to DXS374, confirming a previous localisation to distal Xq28. As 
yet there is no evidence for genetic heterogeneity of Barth syndrome.