We treated 32 patients with Ph1-negative chronic myeloproliferative disorders (CMD) with excessive thrombocytosis with Interferon alpha-2b (IFN alpha-2b): 26 had essential thrombocythaemia, ET (18 previously untreated, eight pretreated); one thrombocythaemia after treatment for Hodgkin's disease (HD); two thrombocythaemia associated with non-Hodgkin's lymphoma (NHL); three stage II idiopathic myelofibrosis (IM).
Western blot analysis using a monoclonal antibody to pp60c-src (327) revealed that protooncogene c-src expression by the platelets of the CMD patient was comparable to the normal control.
CMD has recently been classified into four categories: CMD I, the classical or "pure' CMD without severe impairment of intellectual development; CMD II, the Fukuyama type CMD with muscle and structural brain abnormalities; CMD III and IV with muscle, eye and brain abnormalities; the milder Finnish type CMD (CMD III) and the severe Walker-Warburg syndrome (CMD IV).
In the 'merosin-deficient' subgroup, which represents about half of the cases, more definite evidence of the involvement of the laminin alpha2-chain has recently been reported with the identification of mutations in the gene encoding the alpha2-chain of laminin 2 (LAMA2) in CMD patients.
Approximately half the cases of classical congenital muscular dystrophy (CMD) have a pronounced deficiency or absence of the laminin alpha 2 chain of laminin-2 (merosin).
One ACTN3-deficient CMD patient showed no mRNA expression for the muscle ACTN3 gene, but the other ACTN3-deficient patients with different forms of muscular dystrophy showed very low or no mRNA expression as well.
Deficiency of laminin alpha2 chain caused by mutations of the LAMA2 gene on chromosome 6q2 account for approximately 50% of cases of congenital muscular dystrophy (CMD) in white patients.
Our findings suggest that TGF-beta1 is involved in CMD muscle fibrosis, but differently from what we observed in DMD muscles as it seems not to be the major player in connective tissue proliferation.
As classification of CMD should be based on genetic background, our present cases with typical clinical, myopathological and neuroradiological findings of FCMD without mutation of the fukutin gene may represent a new variant (or variants) of CMD that is different from FCMD.