To my knowledge there's not been a confirmed "deformed shrimp" yet that is linked with inbreeding. That is much more common with mammals. In theory because mammals are built genetically differently to spread out and travel into a much wider range of area, while shrimp are built genetically to be able to accept inbreeding much better since often they may be confined to a much smaller area and have to breed with each other to sustain a population.
This is a post from a different thread:
Shrimp can inbreed for years without any problems. To start a new strain selectively breeding AND inbreeding is necessary. Deformities are not really an issue with shrimp, although I admit that inbreeding depression (lowered fertility) may develop after several years if not introducing new blood.
Here's a quote from the scientific paper from GENETIC DIVERSITY STATUS OF WHITE SHRIMP Litopenaeus vannamei BROODSTOCKS IN MEXICO by Ricardo Perez-Enriquez, Fidencio Hernandez-Martinez, Pedro Cruz*, Manuel Grijalva-Chon, Josefina Ramos-Paredes, Fernando Mendoza-Cano
Centro de Investigaciones Bioldel Noroeste, S.C. (CIBNOR)
Mar Bermejo 195, Col. Playa Palo Santa Rita, La Paz, Baja California Sur, Mexico 23090
"Management practices for almost 10 generations since the introduction of a single stock from Venezuela to Mexico, had permitted the broodstocks to retain high levels of genetic diversity. "
A decrease in the number of alleles were also not found.
This doesn't mean years later they wouldn't have inbred depression, but it is nice to know that the hobbiest has several years before possibly encountering anything.