Karyotype Results

Dr. Antoniou: ‘Take a look at the karyotype below. Note that our patient has an extra chromosome 21.’

She gives a moment for the students to absorb this information.

1998 The Board of Regents of the University of Wisconsin System; https://worms.zoology.wisc.edu/zooweb/phelps/47xy_21.html 

You: ‘This is definitive proof that the little girl has Down’s Syndrome.’

Dr. Antoniou nods in agreement.

‘Now, let’s change our focus to a second family. In that scenario, we suspect an autosomal recessive condition—cystic fibrosis (CF). Since CF arises from a single-gene mutation, our primary tool here involves Mendelian probability calculations. However, you should still keep in mind the broader context of genetic testing, as molecular tests would be needed for definitive diagnosis.’

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