You could use R in combination with the proxy package:
Given your dataset as a tab delimited dataset "dataset.txt":
SNP St1 St2 St3 St4 St5 St6
1284995 0 0 0 1 0 0
1285001 1 1 1 0 1 1
1285017 0 0 0 0 0 0
1285034 0 0 1 0 0 0
1285040 0 1 0 0 0 0
1285070 0 0 0 0 1 1
Then do this in R (you may want to look up the Jaccard similarity, I am not entirely sure if that is the best one to use).
install.packages("proxy")
library(proxy)
## load dataset:
dataset <- read.table(file="dataset.txt", sep="\t", header=T, row.names=1)
## Calculate distance using Jaccard method:
d <- dist(t(dataset), method="Jaccard")
## Hierarchical cluster the data
# Note that I transpose the dataset otherwise I cluster the markers
hc <- hclust(d)
## Plot the data:
plot(hc)

Just in case it helps readers to figure out the kind of data I need to analyze/cluster, here is a sample:
Thanks once more