Retinoblastoma discordance in families with twins

Retinoblastoma has an increased inheritance risk of germline RB1 mutations in offspring and siblings, especially twins. Three families, each having one retinoblastoma-affected twin, were selected for genetic analysis and DNA profiling. Germline RB1 mutations were found in all probands. DNA profiling carried on similar-looking twins of families I and II, proved them to be fraternal. This study demonstrates the importance of genetic analysis of RB1 gene for risk prediction in retinoblastoma families. It also emphasizes that DNA profiling is a mandate for genetic screening of families with twins, thus adding a new dimension in counseling of retinoblastoma.

Lipid storage myopathies with unusual clinical manifestations.

We describe the clinical presentation, course and pathologic findings found in three adult patients with lipid storage myopathy. Excessive lipid storage was found in Type 1 fibers of muscle. Clinical improvement on oral levo-carnitine therapy suggests the possibility of carnitine deficiency as the most likely etiology in two of the patients and one had mitochondrial myopathy confirmed on genetic analysis.