Question

Case Study 12-2 A 7-month-old child suffered from sleep apnea and difficulty breathing. Respiratory infections and allergies were ruled out. From the family history, the physician suspected congenital congestive hypoventilation syndrome (CCHS). CCHS results, in part, from abnormal function of the PHOX2B gene product caused by a triplet-repeat expansion. The expansion of the triplet GCN in the DNA sequence (N is any base) results in the insertion of additional alanines in the Phox2B protein. The symptoms of the syndrome include interruptions in breathing during sleep and other abnormalities in the autonomic nervous system. A blood sample from the patient was tested for the GCN expansion by PCR using primers that flanked the location of the potential expansion. The amplicons were resolved by agarose gel electrophoresis. <Insert Fig 12-26> gcagcagcagcggeggcggecgeggcagcggcogeggcggcageggcagcggcogcagct PHOX2b exon 3 A 1 2 3 4 5 6 7 8 9 10 11 12 PAGE 23 20 -(Normal) D 400- 300. (Normal) 200. Agarose (rapid test)

1. Based on the results from the agarose PCR (240-bp product), how many alanines are likely to be inserted in the PHOXB sequence?

a.   30–40

b. 5–8

c.   15–20

d. 8–12

Answer 1

Juswer: - options" is corrent Answer => 8-12 Explanation & Because 2460-210 = 30bp 3 bp code for one amuno aud. So, number of alanine Pear Rate my Arrunt 30 3 = 10 TWITT