Okay, so I need to figure out which of the options is an autosomal dominant metabolic disorder. Let's start by recalling what autosomal dominant disorders are. They are genetic conditions where only one copy of the mutated gene is needed for the individual to be affected. These are typically caused by a mutation in a single gene located on an autosome (non-sex chromosome), and the affected person has a 50% chance of passing it to their offspring.

Now, thinking about metabolic disorders. Metabolic disorders are diseases that affect the body's ability to convert food into energy. They can be inherited and often involve enzyme deficiencies. Common examples include phenylketonuria (PKU), maple syrup urine disease, and Tay-Sachs disease. Wait, but I need to remember which of these are autosomal dominant versus recessive.

Phenylketonuria (PKU) is autosomal recessive. The same with maple syrup urine disease. Tay-Sachs is also recessive. Then there's Marfan syndrome, which is autosomal dominant, but that's a connective tissue disorder, not metabolic. Wait, but maybe there's another one. Oh, maybe Homocystinuria? There are different types. Classic homocystinuria is autosomal recessive, but there's a form caused by CBS deficiency which is recessive. Alternatively, maybe there's another metabolic disorder that's dominant.

Wait, what about Ehlers-Danlos syndrome? Some types are autosomal dominant, but again, not metabolic. Hmm. Maybe certain types of hyperlipoproteinemia? Familial hypercholesterolemia is autosomal dominant. It's a lipid metabolism disorder. That could be considered a metabolic disorder. So if one of the options is familial hypercholesterolemia, that's the answer. Let me confirm.

Familial hypercholesterolemia is indeed an autosomal dominant disorder caused by mutations in the LDL receptor gene. It leads to high cholesterol levels and early cardiovascular disease. So if that's one of the options, then that's the correct answer. The other options might be diseases like cystic fibrosis (autosomal recessive), Huntington's disease (autosomal dominant but not metabolic), or others.

So the core concept here is recognizing autosomal dominant inheritance in metabolic disorders. The correct answer would be the one that fits both criteria. The wrong options would be either recessive or not metabolic disorders. The clinical pearl here is to remember that while many metabolic disorders are recessive, some like familial hypercholesterolemia are dominant. So the key is to recall specific examples.

**Core Concept**
Autosomal dominant metabolic disorders are inherited conditions caused by a single pathogenic variant in a gene, leading to enzyme dysfunction or altered metabolic pathways. These disorders often manifest with variable expressivity and typically require only one affected parent for transmission.

**Why the Correct Answer is Right**
Familial hypercholesterolemia (FH) is an autosomal dominant metabolic disorder caused by mutations in the LDL receptor gene (*LDLR*), apolipoprotein B (*APOB*), or proprotein convertase subtilisin/kexin type 9 (*PCSK9*). This impairs LDL clearance from the bloodstream, leading to severe hypercholesterolemia and early atherosclerosis. The dominant inheritance pattern means heterozygous individuals (with one mutated allele) exhibit

✓ Correct Answer: D. Familial hyper cholestrolemia