RT Book, Section
A1 Pyeritz, Reed E.
A2 Papadakis, Maxine A.
A2 McPhee, Stephen J.
A2 Rabow, Michael W.
A2 McQuaid, Kenneth R.
SR Print(0)
ID 1193140299
T1 DNA Analysis
T2 Current Medical Diagnosis & Treatment 2023
YR 2023
FD 2023
PB McGraw-Hill Education
PP New York, NY
SN 9781264687343
LK accessmedicine.mhmedical.com/content.aspx?aid=1193140299
RD 2024/04/25
AB Direct  inspection  of  nucleic  acids—often  called  “molecular  genetics”  or  “DNA  diagnosis”—is  an  important  tool  in  a  number  of  clinical  areas,  including  oncology,  infectious  disease,  forensics,  and  the  general  study  of  pathophysiology.  A  major  impact  has  been  in  the  diagnosis  of  mendelian  disorders.  Molecular  testing  is  available  for  more  than  3000  separate  hereditary  conditions.  Once  a  particular  gene  is  shown  to  be  defective  in  a  given  condition,  the  nature  of  the  pathogenic  variant  in  a  patient  can  be  determined  by  sequencing  the  nucleotides  of  the  coding  exons  and  the  splice  sites.  One  of  a  variety  of  techniques  can  then  be  used  to  determine  whether  that  same  pathogenic  variant  is  present  in  other  patients  with  the  same  disorder.  Genetic  heterogeneity  is  so  extensive  that  most  mendelian  conditions  are  associated  with  numerous  pathogenic  variants  at  one  locus—or  often  multiple  loci—that  produce  the  same  phenotype.  Pathogenic  variants  at  several  hundred  different  genes  cause  vitreoretinal  disorders,  such  as  retinitis  pigmentosa,  and  changes  in  several  dozen  genes  cause  familial  hypertrophic  cardiomyopathy.  This  fact  complicates  DNA  diagnosis  of  patients  and  screening  for  carriers  of  defects  in  specific  genes.