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Gene deletions due to unequal crossing-over events represent a not uncommon cause of immunoglobulin isotype deficiency. A variety of deleted haplotypes has been ascertained in the Italian population by means of screening for different Ig isotypes followed by Southern blot analysis of the deficient probands. The total frequency of gene deletions involving the gamma 2 and/or gamma 4 genes amounts to about 1/60; among these, a higher frequency was observed for multigene compared with single gene deletions. Carriers of multiple deficiencies due to gene deletions are able to activate compensation mechanisms, avoiding the usual pathological consequences of the deficiency.

A 32-year-old female presented with progressive external ophthalmoplegia (PEO) and multisystem abnormalities, strikingly associated with myotonia and muscle hypertrophy. These two features were not found in her brother, who had a complex neuromuscular disorder complicating chronic PEO. In both subjects muscle biopsy revealed "ragged-red" fibres and myofibres containing glycogen granules, which were never bound by membranes. A severe demyelinating neuropathy was revealed by electrophysiological and morphological studies. Cranial CT scan showed extensive demyelination of the cerebral white matter. Genetic studies demonstrated that this familial syndrome is transmitted as an autosomal recessive trait.

Two cases of central core disease, father and daughter, of a family with dominant autosomal inheritance, are presented, one with bilateral congenital dislocation of the hip. Muscle biopsy was performed in both cases. Oxidative enzymes evidenced only type I fibers, most of them presenting a central core and not uncommonly more than one. On electron microscopy the cores generally appeared well demarcated from the surrounding fibrils and were characterized by lack of mitochondria and abnormalities of the Z line. Transitional aspects from normal fibers to completely unstructured cores were observed, as well as from well structured and unstructured cores. These findings are discussed in the light of the previous literature and particular attention is paid to the problem of differentiation between central core and multicore disease. The pathogenesis of the muscular alteration is also discussed in relation with the possibility of their neurogenic origin. Eventually, the histochemical and ultrastructural similarities between central cores and target fibers are focused.

Antibody-dependent cytotoxicity mediated by human peripheral lymphocytes is an active energy-requiring phenomenon. In this study the relative importance of glycolysis and respiration was analyzed, by measuring the effect of various metabolic inhibitors (sodium azide, antimycin A, 2-deoxy-D-glucose, iodoacetate), alone or in combination, on effector cell efficiency and intracellular ATP level. The inhibition of both aerobic and anaerobic energy production in the effector cells completely abolished cytotoxicity. An inhibition of 50% was observed when the intracellular ATP concentration was decreased to levels corresponding to 30 to 50% of those in the untreated controls.