This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cytogenetic Disorders, Subject name: Pathology
All are true about chromosomal instability syndrome except- 
Select and explain. 
A. DNA repair defect, B. Autosomal dominant inheritance, C. Increased risk of malignancy, D. Associated immunodeficiency
B: Autosomal dominant inheritance
Answer: B: Autosomal dominant inheritance 
Explanation: Ans. is 'b' i.e., Autosomal dominant inheritanceo Chromosomal instability syndromes are typically transmitted in an autosomal recessive mode of inheritanceChromosome instability syndromeso They are a group of inherited conditions associated with chromosomal instability and breakage. The disorders are characterized by a defect in DNA repair mechanisms or genomic instabilityo Susceptibility to exogenous genotoxic agents such as ultraviolet (UV) light, oxidative stress, and chemical mutagens, can also lead to a variety of nucleotide modifications and DNA strand breakso Patients with these disorders show increased predisposition to cancer.o Another hallmark of these disorders is immunodeficiency, a phenotype caused by an inability to properly repair DNA strand breaks that occur during development of the immune system,o Important chromosomal syndromes are1) Ataxia telangiectasia2) Ataxia telangiectasia-like disorder3) Bloom syndrome4) Fanconi anaemia5) Nijmegen breakage syndrome6) Xeroderma pigmentosum,7) Cockayne's syndrome