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In the period from 1923 to 1986 our pathologists examined pathologic material from 102 patients with alveolar soft-part sarcoma (ASPS). Followup clinical data is available for 91. Median followup is 7 years (range 1 month to 27 years). Local recurrence was only found if residual disease was left at the time of the original excision. Survival in those patients who presented without metastases was 77% at 2 years, 60% at 5 years, 38% at 10 years and 15% at 20 years (median 6 years). No survival advantage could be demonstrated for patients who received chemo and/or radiotherapy, although numbers are small and staging not uniform. An evaluation by electron microscopy and immunohistochemistry cannot confirm recent claims that ASPS is a muscle tumor. ASPS is an unusual neoplasm; the primary therapeutic option is aggressive surgical excision. Survival even with the development of metastases can be long.

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Using the generalized stepwise mutation model, we propose a method of estimating the relative mutation rates of microsatellite loci, grouped by the repeat motif. Applying ANOVA to the distributions of the allele sizes at microsatellite loci from a set of populations, grouped by repeat motif types, we estimated the effect of population size differences and mutation rate differences among loci. This provides an estimate of motif-type-specific mutation rates up to a multiplicative constant. Applications to four different sets of di-, tri-, and tetranucleotide loci from a number of human populations reveal that, on average, the non-disease-causing microsatellite loci have mutation rates inversely related to their motif sizes. The dinucleotides appear to have mutation rates 1.5-2 times higher than the tetranucleotides, and the non-disease-causing trinucleotides have mutation rates intermediate between the di-and tetranucleotides. In contrast, the disease-causing trinucleotides have mutation rates 3.9-6.9 times larger than the tetranucleotides. Comparison of these estimates with the direct observations of mutation rates at microsatellites indicates that the earlier suggestion of higher mutation rates of tetranucleotides in comparison with the dinucleotides may stem from a nonrandom sampling of tetranucleotide loci in direct mutation assays.The mutation rate () at genetic loci and the effective population size (N) are two basic parameters for understanding the genetic structure of a population. Numerous population genetic studies addressed the question of estimating these two quantities individually as well as simultaneously (1-3). For populations with large generation time and overlapping generations, direct estimation of effective population size is problematic (4). Likewise, mutation rates at most genetic loci are not large enough to be directly measured, and inference of true mutational events is also complicated by assumptions regarding biological relationships of the observed pedigrees (5, 6).One alternative is to estimate the mutation rates by indirect procedures that rely on allele frequency distributions in populations (1-3, 5, 7). In these studies it was assumed that (i) population is in a mutation-drift balance, so that the allele frequency distributions in populations could be expressed in terms of N, the product of effective population size (N), and the rate of mutation (); and (ii) that each mutation yields an allele previously not seen in the population (the infinite allele model). The first assumption is reasonable for most large populations, whereas the second may not apply to all loci. In particular, for microsatellite loci, where polymorphisms are caused by differences in the number of tandem repeats, the infinite allele model does not apply (8-10).Recent theoretical work suggests that the within-population variance of repeat unit sizes is proportional to the product of two basic parameters, N and (11, 12), and this relationship holds even when the pattern of mutational changes at microsatell...

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