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Genetic testing and genetic counseling by ggl16746

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									    Genetic testing and genetic
            counseling
I Prenatal screening/testing
II Newborn screening
III Carrier and other adult testing
IV Genetic Counseling



                                      1
I Prenatal screening/testing

1. ultrasound
2. maternal serum alpha-fetoprotein or
       multiple marker screening
3. amniocentesis
4. chorionic villus sampling (cvs)
5. nuchal translucency

                                         2
I Prenatal screening/testing

1. ultrasound                          photograph sonogram
                                       procedure

  usually 18-20 weeks
  for fetal age, movement,
     structural problems

                Fig. 13.6 A sonogram
                is an image obtained
                with ultrasound

                                                             3
I Prenatal screening/testing

2. maternal serum alpha-
  fetoprotein
                               maternal serum
   (or multiple marker         alpha feto-protein
                               screening test
    screen)
  usually 16-18 weeks
  too low: possible
  too high: possible
                                                    4
   I Prenatal screening/testing



                  flow chart for maternal serum screening test




Counseling Aids
for Geneticists
Greenwood
Genetic Center



                                                                 5
I Prenatal screening/testing

3. amniocentesis

  done when significant risk,   photograph
                                amniocentesis
     as, mother over 35,        procedure

     abnormal MSAFP
  14-16 weeks
  karyotype, other tests

                                                6
I Prenatal screening/testing

4. chorionic villus biopsy

                                        chorionic villus
                                        sampling
done when significant risk,             procedure

  as, mother over 35,
10-12 weeks
karyotype
                               Counseling Aids for Geneticists
                               Greenwood Genetic Center

                                                                 7
I Prenatal screening/testing




                               spectral karyotype




   Fig. 13.5 a.and b. Two
   ways to check fetal
   chromosomes



                                                    8
I Prenatal screening/testing


Table 13.2




                               9
I Prenatal screening/testing

5. nuchal translucency
uses ultrasound; allows measurement of
  amount of fluid behind neck of fetus
  (measures clear space seen behind the neck)
best combined with measurements of some
  proteins from maternal blood

                                            10
I Prenatal screening/testing

5. other tests
  preimplantation
    genetic diagnosis



                Fig. 21.5 Preimplantation
                genetic diagnosis


                                            11
II Newborn Screening

1. purpose: to find newborns who will
benefit from early diagnosis and treatment




Table 20.2 Newborn
Screening Tests


                                             12
II Newborn Screening

1. purpose: to find newborns who will benefit
from early diagnosis and treatment
2. historically, the criteria for inclusion in a
newborn screening program:
      preventable damage
      frequency in population
      appropriate test
      needed to recognize disorder
                                              13
II Newborn Screening

3. mandated by state law
  exception allowed for religious objection




                                              14
II Newborn Screening
in Illinois:
1. phenylketonuria
2. galactosemia
3. congenital hypothyroidism
4. biotinidase deficiency
5. hemoglobinopathies
6. congenital adrenal hyperplasia
7. hearing                          15
II Newborn screening

in Illinois:
8. disorders detected by tandem mass
   spectrometry (example: MCAD)
9. cystic fibrosis
10. five lysosomal storage disorders: Pompe,
  Krabbe, Niemann-Pick, Gaucher, Fabry
  (to be implemented)
                                               16
II Newborn screening--tandem mass
spectrometer tests
Amino acid disorders                 Urea cycle disorders
  pku                                   citrullinemia
  maple syrup urine disease             argininosuccinic aciduria
  tyrosinemia, types I, II and III

Organic acid disorders
   3-methylcrotonyl-CoA carboxylase deficiency (3MCC)
   3-hydroxy-3-methylglutaric-CoA lysase deficiency (HMG)
   glutaric aciduria types I and II (GAI, GAII)
   proprionyl CoA carboxylase deficiency (IVA)
   isovaleryl CoA dehydrogenase deficiency
   methylmalonic acidemia (MMA)
   mitochondrial acetoactyl-CoA thiolase deficiency (b-KT)
   ethylmalonic adipic aciduria
                                                                    17
II Newborn screening --tandem mass
spectrometer tests
Fatty acid oxidation disorders
carnitine palmitoyl transferase deficiency type II (CPT II)
long chain 3-hydroxy-coA dehydrogenase deficiency (LCHAD)
medium chain acyl-CoA dehydrogenase deficiency (MCAD)
short chain acyl-CoA dehydrogenase deficiency (SCAD)
trifunctional protein deficiency (TFPD)
very long chain acyl-CoA dehydrogenase deficiency (VLCAD)




                                                              18
II Newborn screening

in Illinois:
8. disorders detected by tandem mass
   spectrometry (example: MCAD)
9. cystic fibrosis
10. five lysosomal storage disorders: Pompe,
  Krabbe, Niemann-Pick, Gaucher, Fabry
  (to be implemented)
                                               19
II Newborn Screening
in Illinois:
1. phenylketonuria
2. galactosemia
3. congenital hypothyroidism
4. biotinidase deficiency
5. hemoglobinopathies
6. congenital adrenal hyperplasia
7. hearing                          20
III Carrier screening
for reproductive decisions
  family history: Tay Sachs, cystic fibrosis,
      sickle cell disease, phenylketonuria

population screening in ethnic groups
  Tay Sachs
  sickle cell disease
  add cystic fibrosis? spinal muscular atrophy?

                                                21
III Carrier screening

for late onset disorders
  Huntington disease
  breast cancer
  hemochromatosis




                           22
Issues in All Genetic Testing

1. Discrimination
    employment related          GINA
    insurance                   GINA
    personal
2. Personal issues
    What do you want to know?
    If it is bad news, who do you tell?
                                          23
IV Genetic counseling

possible problem detected during prenatal testing

birth of an affected child

family diagnosis/history of genetic disorder

repeated unexplained loss of pregnancy

exposure to mutagen

                                               24
IV Genetic counseling

traditionally nondirective (contrast with most
   health care situations)

frequently can give estimates of risk:
  calculated
  empiric data
  test results
                                                 25

								
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