HY USMLE Q #472 – MSK / Genetics — Transcript

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1. 0:00how's it going guys it is 402 am friday
2. 0:02may 20th here in japan and we have a
3. 0:05past level slash easy msk genetics
4. 0:08question for step one okay very wordy
5. 0:11answer choices i'll just cut through the
6. 0:13nonsense not waste your [ __ ] time so
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11. 0:21underscore medical mehl a man underscore
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14. 0:26and channel are down below now start the
15. 0:28clip three-year-old boy a slow motor
16. 0:30development his waddling gait and calf
17. 0:32muscle enlargement frequently uses his
18. 0:34arms to support himself serum creatine
19. 0:37kinase ck is elevated question wants to
20. 0:39know which the following combinations of
21. 0:41findings best reflects
22. 0:43this patient's condition so
23. 0:45you need to know as i prefaced with this
24. 0:47is past level this is duchene muscular
25. 0:49dystrophy which is going to be an
26. 0:51x-linked recessive frame shift mutation
27. 0:54in the dystrophin gene which codes for
28. 0:57alpha beta dystrophy glycan or alpha
29. 1:00beta distroglycan which is a protein
30. 1:03complex that
31. 1:05connects
32. 1:06the cytoskeleton the actin cytoskeleton
33. 1:09of the muscle cell to the extracellular
34. 1:11matrix okay cell membrane can also be an
35. 1:14answer technically but cytoskeleton if
36. 1:16it's listed
37. 1:17this is very high yield for duchene all
38. 1:19right so these patients do not have
39. 1:22genuine
40. 1:23muscular hypertrophy they have what's
41. 1:25called pseudo hypertrophy which is
42. 1:28replacement of the muscle cells with
43. 1:30connective tissue
44. 1:32stromal cells or
45. 1:35fibroadipose tissue okay now
46. 1:39uh this child frequently uses arms to
47. 1:41support himself this is called gower
48. 1:43maneuver we're going to get weakening of
49. 1:45the
50. 1:46proximal muscles of the legs we'll
51. 1:48proceed to the calves and the child will
52. 1:50increasingly need to use his arms to
53. 1:52walk up off the floor
54. 1:54children will become wheelchair-bound
55. 1:56and finally
56. 1:58die from cardiomyopathy okay
57. 2:00now creatine kinase will be elevated due
58. 2:03to muscle breakdown you need to know
59. 2:05that becker muscular dystrophy is a less
60. 2:08severe form of duchenne that is also due
61. 2:11to mutations in the dystrophin gene
62. 2:14albeit not frameshift becker will be a
63. 2:17teenager or a young adult okay rather
64. 2:19than a child here now
65. 2:22i should also just men so the answer i
66. 2:24should articulate is x-linked recessive
67. 2:27cytoskeletal defect fibroadipose tissue
68. 2:30deposition okay this answer right here
69. 2:32now just other things i want to mention
70. 2:34is
71. 2:35ragged red fibers this is a buzzy term
72. 2:38that can sometimes be applied to
73. 2:40mitochondrial disorders okay
74. 2:43mitochondrial disorders will present
75. 2:44with eye or ear problems okay
76. 2:48mitochondria required for the eyes and
77. 2:50ears as well as lactic acidosis and
78. 2:53hypotonia that tetrad okay eye ear
79. 2:57problems uh lactic acidosis hypotonia
80. 2:59high yield for mitochondrial disorders
81. 3:01maternal inheritance and also this
82. 3:04dining arm defect this is buzzy uh for
83. 3:07cartagena syndrome primary ciliary
84. 3:09dyskinesia that's going to be recurrent
85. 3:11pneumonias
86. 3:13with uh situs and versus organs on the
87. 3:15wrong side of the body you know the deal
88. 3:18i'm going to continue to make more
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91. 3:22i appreciate your time that's it