Parasitic worms that attack specific tissues or organs are known as

The answer for the above question is Helminths.
These are parasitic worms that feed on a living host to gain nourishment and protection, while causing poor nutrient absorption, weakness and disease in the host. They are invertebrates characterized by elongated, flat or round bodies, they include flatworms, flukes, tapeworms and nematodes.

The gens present in the dna in the nucleus of the cell in the body