Nijmegen breakage syndrome is a rare autosomal congenital disorder. It originates from mutations in the NBS1 gene located in band 8q21, which encodes for the DNA double strand repair protein Nibrin. Immunodeficiency with increased susceptibility to infection. It is a condition characterized by short stature, an unusually small head size (microcephaly), distinctive facial features, recurrent respiratory tract infections, an increased risk of cancer, intellectual disability, and other health problems. People with this condition typically grow slowly during infancy and early childhood. After this period of slow growth, affected individuals grow at a normal rate but remain shorter than their peers. Microcephaly is apparent from birth in the majority of affected individuals. The head does not grow at the same rate as the rest of the body, so it appears that the head is getting smaller as the body grows (progressive microcephaly).Individuals with Nijmegen breakage syndrome have distinctive facial features that include a sloping forehead, a prominent nose, large ears, a small jaw, and outside corners of the eyes that point upward (up slanting palpebral fissures). These facial features typically become apparent by age 3.