TY  - CHAP
M1  - Book, Section
TI  - Alpha-Thalassemia
A1  - Galanello, Renzo
A1  - Cao, Antonio
A1  - Origa, Raffaella
A2  - Murray, Michael F.
A2  - Babyatsky, Mark W.
A2  - Giovanni, Monica A.
A2  - Alkuraya, Fowzan S.
A2  - Stewart, Douglas R.
Y1  - 2014
N1  - 
T2  - Clinical Genomics: Practical Applications in Adult Patient Care
AB  - Disease  summary:Alpha-thalassemia  is  one  of  the  most  common  hemoglobin  (Hb)  genetic  disorder,  characterized  by  reduced  or  absent  production  of  the  alpha-globin  chains,  especially  frequent  in  Mediterranean,  South  East  Asia,  Africa,  India,  and  the  Middle  East.Four  main  conditions  resulting  from  deletion  or  inactivation  (nondeletion  mutants)  of  one,  two,  three,  or  all  four  alpha-globin  genes  are  recognized.  Carriers  of  alpha0-thalassemia  (two  deleted  alpha-globin  genes,  ie,  alpha-thalassemia  trait)  show  microcytosis,  hypochromia,  and  normal  percentages  of  HbA2  and  HbF,  carriers  of  alpha+-thalassemia  (one  deleted  or  nonfunctional  alpha-globin  gene,  ie,  alpha-thalassemia  silent  carrier)  have  either  a  silent  hematologic  phenotype  or  present  with  a  moderate  thalassemia-like  hematologic  picture.  Two  are  the  alpha-thalassemia  clinically  significant  forms:  Hb  Bart  hydrops  fetalis  syndrome  and  HbH  disease  (four  and  three  deleted  or  nonfunctional  alpha-globin  genes,  respectively).  Hb  Bart  hydrops  fetalis  syndrome  is  the  most  severe  form,  characterized  by  fetal  onset  of  generalized  edema,  pleural  and  pericardial  effusions,  and  severe  hypochromic  anemia,  in  the  absence  of  ABO  or  Rh  blood  group  incompatibility.  Death  usually  occurs  in  the  neonatal  period.  HbH  disease  is  characterized  by  microcytic,  hypochromic  hemolytic  anemia,  hepatosplenomegaly,  mild  jaundice,  and  sometimes  thalassemia-like  bone  changes.  Detection  of  red  blood  cell  inclusion  bodies  (precipitated  HbH)  with  supravital  stain  and  HbH  by  hemoglobin  analysis  with  high-performance  liquid  chromatography  (HPLC)  or  electrophoresis  is  diagnostic  for  HbH  disease.  Genetic  testing  is  used  to  confirm  hematologic  and  clinical  diagnosis  and  is  useful  in  carriers  for  genetic  counseling.  If  both  parents  carry  an  alpha0  mutation,  they  have  a  risk  of  25%  of  having  an  offspring  with  Hb  Bart  syndrome  at  each  conception.  In  patients  with  HbH,  genetic  testing  has  a  prognostic  value,  as  interactions  between  nondeletional  molecular  defects  or  between  deletional  and  nondeletional  defects  result  in  more  severe  phenotypes  than  interactions  with  deletional  molecular  defects.  
SN  - 
PB  - McGraw-Hill Education
CY  - New York, NY
Y2  - 2024/04/19
UR  - accessbiomedicalscience.mhmedical.com/content.aspx?aid=1102700190
ER  -