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Eighteen Swedish patients with familial amyloidotic polyneuropathy were tested for the met30 mutation of the transthyretin (TTR) (prealbumin) gene by RFLP analysis of genomic DNA using the restriction enzyme NsiI. The results confirmed previous findings that the Swedish variant of familial polyneuropathy has the same valine by methionine substitution at position 30, as seen in patients with FAP from Japan, Portugal or patients of Swedish descent from USA. However, two of the patients were homozygous, totally lacking the wild type allele. Measurable serum values for the variant transthyretin (TTR) was detected with a RIA-method in all the 18 Swedish FAP patients studied with a mean concentration of 12.1 +/- 5.1 (SD) mg/100 ml, (11.0 +/- 4.1 when the two homozygotes were excluded). In 45 Japanese patients the mean was 9.2 +/- 2.7 mg/100 ml. The variant TTR was not detected in the healthy controls. The value for the variant TTR was nearly twice that high in the two homozygous patients, 21.14 and 21.16 mg/100 ml, respectively. There was no correlation between the serum levels of variant TTR and the duration of disease or levels of serum albumin in the FAP-patients.

All cases of motor neuron disease (MND), encompassing amyotrophic lateral sclerosis (ALS), progressive bulbar paralysis (PBP) and progressive spinal muscular atrophy (PSMA), in northern Sweden, diagnosed between 1969-1980 have been analysed. 128 cases were found, corresponding to an average annual incidence rate of 1.67 per 100,000. The prevalence on December 31, 1980 was 4.8 per 100,000. Age-specific incidence rates were higher in the high age groups with a maximum at 60-64 years for males, at 70-74 years for females and at 65-69 years for the sexes combined. The median age at onset was 61 years. Clustering was not found in mining districts and overrepresentation of miners and stone treaters was not observed. Minor differences in incidence rates, as measured by the standardized morbidity ratio, SMR, were found between the inland, coastal and mountain areas. The median survival time after onset of disease was 32 months for ALS, 30 months for PBP and 70 months for PSMA. The combined survival rate for all MND cases was 28% after 5 years and 15% after 10 years. The male to female ratio was 1.1:1, and 4.7% were familial cases.