Incontinetia pigmenti-related myopathy or unsolved "double trouble"?

Incontinentia pigmenti is an X-linked dominant or sporadic multisystemic disorder with involvement of skin, eyes and central nervous system which results from mutations in the gene for NF-kappaB essential modulator (NEMO). We report on a patient with genetically confirmed Bloch-Sulzberger syndrome, who presented with a progressive myopathy and cardiomyopathy. Genetic analyses revealed an intragenic deletion (Intron3 and Exon10) of the NEMO/IKKgamma/IKKAP/IKBKG gene. Further complete sequencing of genes encoding for desmin, lamin A/C, emerin, and FHL1 showed no evidence of pathogenic mutations. A pathological expansion of CCTG repeats of the ZNF9 gene (PROMM) was ruled out by PCR amplification analysis. MLPA-analysis showed no evidence for duplications or deletions of the dystrophin gene. This report highlights the unusual combination of a genetically confirmed incontinentia pigmenti and a proximal myopathy and dilatative cardiomyopathy of unknown origin. We discuss that the striated muscle involvement (i) might be based on the observed intragenic deletion of the NEMO gene, or (ii) on an additional gene defect leading to an adult onset myopathy. Further studies on neuromuscular involvement in patients with incontinentia pigmenti are needed to clarify this issue.