XRN1 and telangiectasis: For example, Atr, Xrn1, and 1700065D16Rik all had high levels of Pol II within 60 bp of their TSS in leptonema/zygonema (Atr: Ataxia telangiectasia and Rad3 related, required for homologous recombination and synapsis30; Xrn1: 5′−3′ exoribonuclease 1, involved in replication-dependent histone mRNA degradation31; 1700065D16Rik: uncharacterized protein, expression restricted to the testis32).