Which one of the following disorder is inherited in an Autosomal Dominant manner?
**Core Concept**
Autosomal Dominant disorders are characterized by the presence of a single copy of the mutated gene, which is sufficient to cause the condition. This means that a single mutated allele is enough to express the disease phenotype. Autosomal Dominant disorders are usually expressed in every generation and affect both males and females equally.
**Why the Correct Answer is Right**
The correct answer is Cystinuria, which is an inherited disorder that affects the kidneys and intestines. It is caused by a mutation in the SLC3A1 or SLC7A9 genes, which code for the cystine transporter in the kidneys and intestines. In Autosomal Dominant Cystinuria, a single copy of the mutated gene is sufficient to cause the disease, leading to the formation of cystine stones in the kidneys and urinary tract. The mutation affects the cystine transporter, leading to an imbalance of cystine in the urine, which then precipitates out and forms stones.
**Why Each Wrong Option is Incorrect**
**Option A:** Alport Syndrome is inherited in an X-linked pattern, meaning it is more common in males and is caused by mutations in the COL4A5 gene on the X chromosome.
**Option B:** Familial Hypercholesterolemia is inherited in an Autosomal Co-dominant pattern, meaning that both copies of the gene must be mutated to cause the disease. It is caused by mutations in the LDLR gene, which codes for the low-density lipoprotein receptor.
**Option D:** Cystic Fibrosis is inherited in an Autosomal Recessive pattern, meaning that two copies of the mutated gene (one from each parent) are necessary to cause the disease. It is caused by mutations in the CFTR gene, which codes for the cystic fibrosis transmembrane conductance regulator.
**Clinical Pearl / High-Yield Fact**
Remember that Autosomal Dominant disorders can be expressed in every generation, and a single copy of the mutated gene is sufficient to cause the disease. This is in contrast to Autosomal Recessive disorders, which require two copies of the mutated gene to express the disease.
**Correct Answer: C. Cystinuria**