MS incidence rose markedly over 3 decades in a genetically stable population in tandem with a transition from rural to urban living, thus possibly implicating environmental factors introduced by urbanization.

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Since the spring of 1997, when the Neurology Department of the University Hospital of Crete admitted its first patient, nine cases (eight neuropathologically confirmed and one probable) of sporadic Creutzfeldt-Jakob disease (sCJD) have been recorded. This represents an annual incidence five-fold higher than expected based on the island's population (0.54 million). Molecular analysis of the prion-protein gene (PRNP) showed no mutations in any of the seven CJD cases studied. Five patients (ages 64-88 years) were homozygous for methionine-129 of PRNP and showed the classic sCJD triad (subacute dementia, myoclonus, periodic electroencephalogram). Brains contained type 1 (unglycosylated 21.5 kDa band) protease-resistant prion protein (PrPres). Two patients (ages 56 and 57 years), both homozygous for valine-129, showed cerebellar ataxia and later dementia not associated with periodic electroencephalogram; brain PrPres was type 2. Genotyping of 205 Cretan controls showed that methionine-129 homozygosity, a susceptibility factor for sCJD, was significantly higher in this population than in other Caucasian populations (57.0% n = 205 vs. 41.5% n = 859, p < 0.0001). These data are the first to relate a high regional incidence rate for sCJD to the distribution of PRNP 129 genotypes in the local population; however, additional factors may be operational.

The familial spastic paraplegias (FSPs) are heterogeneous neurologic disorders that are known to occur clinically as "pure" or "complicated" forms. Although some of the complicated FSPs have been linked to specific metabolic defects, the pure forms of this disorder remain idiopathic and are considered to be primary system degenerations. We report the case of a 28-year-old man who has evidenced a neurologically pure spastic paraparesis since age twenty-five. Consistent with this diagnosis were the findings of magnetic resonance imaging, which revealed atrophy of the thoracic spinal cord without evidence for white matter disease in the cerebrum, cerebellum, or brainstem. His 32-year-old brother has also evidenced progressive spastic paraparesis since age 30, but his case is confounded by a severe head injury at age 24 that caused a skull fracture and a focal demyelinating lesion of the right frontal lobe. Both patients have had hypogonadism, requiring treatment with testosterone, since age 20. Measurement of plasma levels of very long-chain fatty acids (VLCFA) revealed that both brothers had concentrations diagnostic of adrenoleukodystrophy; their mother had plasma VLCFA levels in the heterozygous range. We conclude that neurologically pure FSP can be an early manifestation of adrenoleukodystrophy and that levels of plasma VLCFA should be determined for all cases of FSP in which X-linked inheritance appears tenable. These considerations may have bearing on the ongoing linkage studies for these disorders.

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