RT Book, Section
A1 Harel, Tamar
A1 Lupski, James R.
A1 Liu, Pengfei
A2 Kline, Mark W.
SR Print(0)
ID 1182930618
T1 Laboratory Analysis of Copy Number and Single Nucleotide Variants
T2 Rudolph's Pediatrics, 23e
YR 2018
FD 2018
PB McGraw-Hill Education
PP New York, NY
SN 9781259588594
LK accesspediatrics.mhmedical.com/content.aspx?aid=1182930618
RD 2024/04/19
AB Cytogenetics  is  a  field  of  genetics  involved  with  the  study  of  chromosomes.  Clinical  cytogenetics  aims  to  delineate  the  gross  chromosomal  abnormalities,  both  in  number  and  structure,  associated  with  certain  malformation  syndromes.  Approximately  1%  of  live-born  babies  have  a  cytogenetic  abnormality,  making  this  field  particularly  relevant  in  the  pediatric  population  and  the  clinical  practice  of  pediatrics.  Cytogenetics  includes  routine  analysis  of  G  (Giemsa)-banded  chromosomes,  fluorescence  in  situ  hybridization  (FISH),  and  whole-genome  array  comparative  genomic  hybridization  (aCGH)  and  single  nucleotide  polymorphism  (SNP)  arrays.  Whole-genome  sequencing  (WGS),  which  has  been  viewed  traditionally  as  a  molecular  technique  targeting  single  nucleotide  variants  (SNVs),  is  gradually  being  introduced  into  the  cytogenetics  field  because  of  its  potential  to  analyze  copy  number  variants  (CNVs)  as  well  as  structural  variants  (SVs).  WGS  can  be  implemented  postnatally  as  well  as  prenatally,  from  fetal  DNA  in  maternal  blood.  Whole-exome  sequencing  (WES)  focuses  on  the  coding  sequences  of  all  genes  in  the  human  genome  (~1%  of  the  human  genome).  It  detects  small  changes  in  DNA  including  SNVs  and  indels  (insertions  and  deletions  <50–100  bp).  WES  has  been  particularly  useful  clinically  for  elucidating  the  etiologic  molecular  diagnosis  in  pediatric  patients  whose  phenotype  remained  a  diagnostic  dilemma  and  for  finding  dual  molecular  diagnoses  in  patients  with  blended  phenotypes.