What is a characteristic of autosomal dominant disorders?
Females are carriers when heterozygous, while males show signs of the disorder.
These disorders are carried on the Y chromosome and can skip generations.
An affected parent has a 50% probability of passing the disorder to each child.
There is a 50% probability that each child will be born with the carrier genotype.
The Correct Answer is C
Choice A reason: Autosomal dominant disorders affect both genders equally, as they are not sex-linked. Heterozygous individuals express the disorder, not just males, due to the dominant allele on an autosome. The idea of females being carriers only applies to X-linked recessive disorders, making this choice scientifically inaccurate.
Choice B reason: Autosomal dominant disorders are caused by mutations on autosomes, not the Y chromosome, which is sex-linked and primarily affects males. These disorders do not typically skip generations, as the dominant allele is expressed in every affected individual, making this choice incorrect.
Choice C reason: In autosomal dominant disorders, a single mutated allele is sufficient for expression. An affected parent (heterozygous) has one normal and one mutated allele, leading to a 50% chance of passing the mutated allele to each child, causing the disorder. This genetic inheritance pattern makes this the correct choice.
Choice D reason: In autosomal dominant disorders, there is no "carrier" state as in recessive disorders, because heterozygous individuals express the disorder. The 50% probability applies to inheriting the disorder itself, not a carrier genotype, which is a concept relevant to autosomal recessive disorders, making this choice incorrect.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Choice A reason: Graves’ disease, a form of hyperthyroidism, does not typically cause decreased calcium. It may lead to hypercalcemia due to increased bone resorption from elevated thyroid hormone levels, which enhance osteoclast activity, making decreased calcium an incorrect laboratory finding for this condition.
Choice B reason: Graves’ disease is characterized by increased thyroid hormone production, including elevated T4 due to autoimmune stimulation of the thyroid. Decreased T4 is associated with hypothyroidism, not hyperthyroidism, making this choice incorrect as it contradicts the pathophysiology of Graves’ disease.
Choice C reason: Increased TSH is seen in primary hypothyroidism, where the thyroid is underactive. In Graves’ disease, TSH is typically decreased due to negative feedback from elevated thyroid hormones (T3 and T4), making this choice incorrect for the expected laboratory profile.
Choice D reason: Graves’ disease causes hyperthyroidism, with increased production of thyroid hormones, including T3, due to autoantibodies stimulating TSH receptors. Elevated T3 levels drive metabolic symptoms like weight loss and tachycardia, making this the correct laboratory finding for Graves’ disease.
Correct Answer is A
Explanation
Choice A reason: Gamma-aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the central nervous system, reducing neuronal excitability by opening chloride channels, hyperpolarizing neurons, and preventing action potentials, making this the correct choice.
Choice B reason: Norepinephrine is an excitatory neurotransmitter and hormone, increasing neuronal activity and arousal in the sympathetic nervous system. It does not inhibit neural signaling, making this choice incorrect for an inhibitory neurotransmitter.
Choice C reason: Histamine acts as a neurotransmitter promoting wakefulness and arousal, not inhibition. It stimulates neuronal activity in the brain, unlike inhibitory neurotransmitters that reduce firing, making this choice incorrect for the role.
Choice D reason: Glutamate is the primary excitatory neurotransmitter, promoting neuronal firing by depolarizing neurons via ion channel activation. It does not inhibit neural activity, making this choice incorrect for an inhibitory neurotransmitter.
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