The following genetically altered mouse strains are available from Jackson Laboratory:

TRF1 flox
A. Sfeir, S.T. Kosiyatrakul, D. Hockemeyer, S.L. MacRae, J. Karlseder, C.L. Schildkraut, T. de Lange (2009) Mammalian telomeres resemble fragile sites and require TRF1 for efficient replication. Cell.138:90-103.

Jackson Lab URL: http://jaxmice.jax.org/strain/012336.html 
Strain Name: B6;129P2-Terf1tm2.1Tdl/J
Stock Number: 012336

TRF2 flox
G. Celli and T. de Lange (2005) DNA processing not required for ATM activation or the telomere damage response after conditional deletion of mouse TRF2. Nature Cell Biol. 7: 712-718

Jackson Lab URL: http://jaxmice.jax.org/strain/006568.html 
Strain Name: Strain Name: B6;129P2-Terf2tm1Tdl/J
Stock Number: 006568

RAP1 flox
A. Sfeir, S. Kabir, M. van Overbeek, G.B. Celli, T. de Lange (2010) Loss of Rap1 induces telomere recombination in the absence of NHEJ or a DNA damage signal. Science 327: 1657-1661.

Jackson lab URL: http://jaxmice.jax.org/strain/012346.html
Strain Name: B6;129-Terf2iptm1.1Tdl/J
Stock Number: 012346

POT1a flox
D. Hockemeyer, J.-P. Daniels, H. Takai, and T. de Lange (2006) Recent expansion of the telomeric complex in rodents: two distinct POT1 proteins protect mouse telomeres. Cell 126: 63-77.

Jackson Lab URL: http://jaxmice.jax.org/strain/014168.html
Strain Name: B6;129-Pot1atm1.1Tdl/J
Stock Number: 014168

POT1b flox
D. Hockemeyer, J.-P. Daniels, H. Takai, and T. de Lange (2006) Recent expansion of the telomeric complex in rodents: two distinct POT1 proteins protect mouse telomeres. Cell 126: 63-77.

Jackson Lab URL: http://jaxmice.jax.org/strain/014169.html 
Strain Name: B6;129-Pot1btm1.1Tdl/J
Stock Number: 014169

TIN2 DC

D. Frescas and T. de Lange (2014) A TIN2 dyskeratosis congenita mutation causes telomerase-independent telomere shortening in mice. Genes Dev. 28: 153-166.

Jackson Lab URL: http://jaxmice.jax.org/strain/024859.html

Strain Name: B6(Cg)-Tinf2tm2.1Tdl/J

Stock Number: 024859