Human Development Lecture 13 – Prenatal screening
First trimester prenatal diagnosis
Diagnostic tools;
- Preconception; genetic screening of parents
- Post-conception;
o Preimplantation/post-implantation
o Genetic screening of cells of embryo/fetus
o Screening fluids for presence/absence of specific proteins
Screening when known family history/disease, high risk group.
DNA testing methods;
- Specific diseases are sex-specific (X-linked); first test is to check the sex of
the child (when visible, otherwise by DNA)
- Hybridization techniques; FISH; Fluorescent In Situ Hybridization (FISH);
Probes (fragment of DNA or RNA which can be radioactively labeled, it detect
presence of nucleotide sequence) bind to parts of single stranded
chromosome with high degree of sequence complentarity. Fluorescent bind to
the probes. Used to detect and localize the presence or absence of specific
DNA sequences on chromosome.
- PCR using fluorescence probes
Preimplantation Genetic diagnostics (PGD);
Parents are both carriers, question is PGD for second child? What could they do?
IVF, removal of one blastomere for genetic analysis. If it is a genetic order, it is in all
cells. So, only one cells is taken out. This one dies.
Only unaffected embryos are transferred to the mother.
During/after IVF it is necessary to take hormone progesterone!
Congenital anomalies (aangeboren afwijkingen);
- Unknown/multiple cause; SUA (single umbilical artery). Co-occurs (komt
samen voor met) Down syndrome & failure of kidneys (VATER)
SUA more in twins.
- Association; group of anomalies with high co-occurence (2 dingen samen
voorkomen)
- Syndrome; group of anomalies with specific cause
Factors involving environment;
- Teratogens;
- Food & vitamins
- Morphogen flukes; often by teratogens
Retinoic acid (metabolite of vitamin A (retinol)) production from retinol depends on
ADH (alcohol dehydrogenase)
It overkills; acne treatment. Defects in neural tube and cardiac. But, RA is necessary
for normal development; not too little, not too much.
Cretinism (iodine deficiency syndrome); bone deformation, mental retardation
(vertraging)
Folic acid deficiency (foliumzuurgebrek); neural tube defects (spina bifida)
First trimester prenatal diagnosis
Diagnostic tools;
- Preconception; genetic screening of parents
- Post-conception;
o Preimplantation/post-implantation
o Genetic screening of cells of embryo/fetus
o Screening fluids for presence/absence of specific proteins
Screening when known family history/disease, high risk group.
DNA testing methods;
- Specific diseases are sex-specific (X-linked); first test is to check the sex of
the child (when visible, otherwise by DNA)
- Hybridization techniques; FISH; Fluorescent In Situ Hybridization (FISH);
Probes (fragment of DNA or RNA which can be radioactively labeled, it detect
presence of nucleotide sequence) bind to parts of single stranded
chromosome with high degree of sequence complentarity. Fluorescent bind to
the probes. Used to detect and localize the presence or absence of specific
DNA sequences on chromosome.
- PCR using fluorescence probes
Preimplantation Genetic diagnostics (PGD);
Parents are both carriers, question is PGD for second child? What could they do?
IVF, removal of one blastomere for genetic analysis. If it is a genetic order, it is in all
cells. So, only one cells is taken out. This one dies.
Only unaffected embryos are transferred to the mother.
During/after IVF it is necessary to take hormone progesterone!
Congenital anomalies (aangeboren afwijkingen);
- Unknown/multiple cause; SUA (single umbilical artery). Co-occurs (komt
samen voor met) Down syndrome & failure of kidneys (VATER)
SUA more in twins.
- Association; group of anomalies with high co-occurence (2 dingen samen
voorkomen)
- Syndrome; group of anomalies with specific cause
Factors involving environment;
- Teratogens;
- Food & vitamins
- Morphogen flukes; often by teratogens
Retinoic acid (metabolite of vitamin A (retinol)) production from retinol depends on
ADH (alcohol dehydrogenase)
It overkills; acne treatment. Defects in neural tube and cardiac. But, RA is necessary
for normal development; not too little, not too much.
Cretinism (iodine deficiency syndrome); bone deformation, mental retardation
(vertraging)
Folic acid deficiency (foliumzuurgebrek); neural tube defects (spina bifida)
