The analysis of multifactorial diseases requires the efficient investi
gation of large numbers of (gene) loci and patient (family) samples. S
ince simple repetitive DNA markers are dispersed all over the chromoso
mes; molecular techniques employing these tools render most convention
al screening procedures obsolete. Examples of tumors, autoimmune disea
ses and infections are presented to validate concepts of indirect gene
diagnoses via simple, tandemly arranged, repetitive DNA sequences. Th
e salient advantages of microsatellite technologies vs. those of multi
locus DNA fingerprinting are weighed.