MLH1 and oligospermia: We here reported a single man with severe oligospermia and a ring chromosome 4 with a microdeletion at 4p16.3.<h4>Results</h4>Synapsis (as SCP3), recombination (as MLH1) and transcriptional inactivation (as BRCA1) in a testicular biopsy were examined by fluorescence immunostaining.