]> 2026-07-31T09:39:50+00:00 WBR0100 0 en Mutation Gene deletion While a deletion of the wild type allele of the ''RB'' gene could cause the “second hit” to the ''RB'' gene, the normal karyotype of chromosome 13 makes this possibility less likely. Mitotic recombination Gene duplication Methylation Genetics A 4-year-old boy is brought by his mother to the physician's office for an immigration medical exam. He has recently immigrated with his family from Brazil to the United States. His mother reports that the boy has begun bumping into furniture very often; she has concerns that his vision may be compromised. She shows you an image in which the pupil of his left eye has a bright whitish reflection due to the camera flash. Upon further questioning, it is revealed that the boy’s father underwent surgery at a young age, leaving him blind in both eyes. Two days later, the offending lesion is surgically removed and the tissue is analyzed for molecular genetic features. Chromosome 13 displays a normal karyotype. A set of common single nucleotide polymorphisms (SNPs) on chromosome 13q is profiled and the resulting SNP identities are displayed below. Assume all of the SNPs have an allelic fraction in the general population of approximately 50%. The ''RB1'' gene spans positions 48,934,153 to 48,951,170 on chromosome 13. Which of the following molecular events most likely occurred in the boy’s somatic tissues to cause his condition? <table> <tr><td>SNP ID</td><td>Chromosome</td><td>Genomic Position</td><td>Genotype</td></tr> <tr><td>rs4771054</td><td>13</td><td>27562342</td><td>CC</td></tr> <tr><td>rs17626553</td><td>13</td><td>28968770</td><td>CT</td></tr> <tr><td>rs2776961</td><td>13</td><td>30101280</td><td>GT</td></tr> <tr><td>rs144430040</td><td>13</td><td>31085367</td><td>CC</td></tr> <tr><td>rs4941731</td><td>13</td><td>33568060</td><td>GG</td></tr> <tr><td>rs9528533</td><td>13</td><td>34588335</td><td>CT</td></tr> <tr><td>rs9548644</td><td>13</td><td>39720610</td><td>AA</td></tr> <tr><td>rs9315803</td><td>13</td><td>41623184</td><td>GT</td></tr> <tr><td>rs9634767</td><td>13</td><td>42270305</td><td>CT</td></tr> <tr><td>rs2044732</td><td>13</td><td>42833400</td><td>AG</td></tr> <tr><td>rs17536002</td><td>13</td><td>43035209</td><td>TT</td></tr> <tr><td>rs11619528</td><td>13</td><td>44826355</td><td>TT</td></tr> <tr><td>rs12866473</td><td>13</td><td>46037501</td><td>CC</td></tr> <tr><td>rs1413077</td><td>13</td><td>47875303</td><td>AA</td></tr> <tr><td>rs7329865</td><td>13</td><td>49154165</td><td>AA</td></tr> <tr><td>rs895967</td><td>13</td><td>49347566</td><td>GG</td></tr> <tr><td>rs2191226</td><td>13</td><td>50940143</td><td>AA</td></tr> <tr><td>rs4943003</td><td>13</td><td>52090383</td><td>GG</td></tr> <tr><td>rs476136</td><td>13</td><td>53413498</td><td>GG</td></tr> <tr><td>rs10507581</td><td>13</td><td>54154463</td><td>GG</td></tr> <tr><td>rs9591632</td><td>13</td><td>55611511</td><td>CC</td></tr> <tr><td>rs4885962</td><td>13</td><td>56863954</td><td>AA</td></tr> <tr><td>rs2592866</td><td>13</td><td>58226942</td><td>GG</td></tr> <tr><td>rs1411645</td><td>13</td><td>59052343</td><td>CC</td></tr> <tr><td>rs6562010</td><td>13</td><td>59711493</td><td>TT</td></tr> </table> C General Principles 2020-10-27T23:20:48Z 2459150.4727778 WBR0100