Autosomal recessive, cancer syndrome in children is –
**Core Concept**
Ataxia-Telangiectasia (AT) is a rare, autosomal recessive genetic disorder characterized by progressive cerebellar ataxia, telangiectasias, and an increased risk of malignancies, particularly lymphomas and leukemias. This condition primarily affects children and is caused by mutations in the ATM gene.
**Why the Correct Answer is Right**
ATM (ataxia-telangiectasia mutated) is a kinase that plays a crucial role in the repair of DNA double-strand breaks by activating the cell cycle checkpoints, thereby preventing the propagation of damaged cells. Mutations in the ATM gene lead to impaired DNA repair, leading to genomic instability, cancer predisposition, and the characteristic clinical features of AT. The condition also involves a deficiency in immunoglobulin production due to impaired V(D)J recombination, making affected individuals more susceptible to infections.
**Why Each Wrong Option is Incorrect**
**Option A:** Fanconi anemia is another autosomal recessive disorder characterized by congenital abnormalities, bone marrow failure, and a predisposition to malignancies. However, it is caused by mutations in the FANCA, FANCC, FANCD1, FANCD2, FANCE, FANCI, FANCJ, FANCL, FANCM, FANCN, FANCO, or FANCQ genes, not the ATM gene.
**Option B:** Li-Fraumeni syndrome is an autosomal dominant disorder caused by mutations in the TP53 tumor suppressor gene, leading to a predisposition to various cancers, including breast, brain, and sarcomas.
**Option C:** Bloom syndrome is an autosomal recessive disorder characterized by short stature, a high risk of cancer, and a propensity for genomic instability, but it is caused by mutations in the BLM gene, not the ATM gene.
**Clinical Pearl / High-Yield Fact**
The ATM gene is a DNA damage sensor that plays a critical role in maintaining genomic stability. Mutations in the ATM gene not only lead to the clinical features of AT but also increase the risk of cancer and other disorders, highlighting the importance of this gene in maintaining cellular homeostasis.
**Correct Answer: C. Bloom syndrome is an autosomal recessive disorder characterized by short stature, a high risk of cancer, and a propensity for genomic instability, but it is caused by mutations in the BLM gene, not the ATM gene.**