A client who was newly diagnosed with Huntington disease (HD) presents with their two children to the genetic clinic for counseling and testing. The nurse should prepare the children for which of the following specimen collection for genetic testing?

Rationale: A. Blood specimen collection is sometimes used for genetic testing, but for Huntington disease, buccal swab testing is the preferred method, especially in children or outpatient settings, because it is non-invasive, painless, and easier to collect. Blood collection can be more invasive and may not be necessary when DNA can be obtained from cheek cells. B. Buccal swab specimen collection is correct. Huntington disease testing requires DNA analysis to detect the CAG trinucleotide repeat expansion in the HTT gene. Buccal cells collected via a cheek swab provide sufficient DNA for polymerase chain reaction (PCR) testing, making this the most appropriate and least invasive method for children or adults undergoing genetic counseling. C. Sweat specimen collection is incorrect because sweat testing is not used for Huntington disease. Sweat is primarily used for testing cystic fibrosis through chloride levels, not DNA analysis for neurodegenerative disorders. D. Hair specimen collection is incorrect because hair alone typically does not provide sufficient DNA for reliable testing of Huntington disease, especially for accurate determination of the CAG repeat expansion.