Neonatal screening Flashcards
While traditional newborn screening was only concerned with a few inborn errors that led to mental retardation, programs now include disorders that can cause what four things?
premature death, infectious diseases, hearing disorders and even heart problems.
Currently the DNA research and Human Genome project are used as secondary confirmation of newborn screening conditions but one day we want them to work how?
as routine primary screening tools
WHy do you need hearing screening programs?
cuz genetic tests cannot detect his and 1 to 3 of every 1000 babies have hearing loss
What are the specimens and tests you want to do on newborns?
blood test, urine, feces
Protein analysis, DNA studies
After you do your routine blood and urine tests on the newborns, what else do you have to do?
secondary level metabolic screening
paristological test (toxoplasmosis)
diagnostic confirmation via tertiary biochemical or molecular genetic testing
What are the 2nd level tests?
urine metabolic screening (battery qualitiative test)
urine organic acid analysis (gas chromo mass spectrometetry)
plasma AAs analysis (mass spec)
DNA tests (for structure and integrity of genes)
What are tertiary level tests?
Specific “in tissue” enzyme analysis (Biopsy)
Liver Skin fibroblasts Leucocytes Erythrocytes Muscle
Molecular (DNA, Protein) diagnostics if available
How do you use mass spectrometry?
protein extraction, place on gel (use electrophoresis), gel digests protein-> liquid chromo-> electro spray-> Mass spectrometry
What are the principles of mass spectrometry?
sample-> ionization and adsorption-> fragmentation->mass analysis-> detection
(blank) are proteins which perform chemical functions
(blank) are proteins that make up the physical structure of the organism
active proteins
structural proteins
Why do you want to sequence DNA and how do you want to do this?
to find single/ multiple nucleotide mutations
Use dried blood
Do you want to use fresh blood samples for mapping mutations?
yes you do, but not very good for newborns
How do you use fresh blood to map mutations?
fresh blood-> WBC cultures-> karyotype -> apply DNA probes for DNA target-> map mutations
(blank) is a single phenotypic trait whose expression is controlled by the action of a single gene locus. It can be autosomal or “X”- or “Y”- linked, it can also be dominant or recessive.
monogenic trait
(blank) is a a single phenotypic trait whose expression is controlled/affected by the action of more than one gene locus.
polygenic trait
If a mutation is at the end of a gene then it is a (blank) mutation
neutral
What is a null mutation?
a very dangerous mutation that is in an exon or promotor and results in a non-functional enzyme
A (blank) mutation reduces but does not destroy phenotypic expression of wild type
leaky
A (blank) mutation is a change in base sequence that does not alter wild type enzyme function.
silent
If one gene is mutated, what kind of effect on the body will it have?
a cascade effect HORIZONTALLY!!!! (not vertically)
How do you manage a pathologic enzyme in metabolism?
you treat symptoms try to fix messed up enzyme (replacement, stabilization, gene transfer) limit the upstream reactants activate alternate pathways supplement the product
(blanK) results from an altered synthesis of a protein (CFTR) involved in the transport of chloride ions. The major clinical consequences abnormally thickened mucous secretions in the lungs and digestive systems.
CF
What does CFTR protein do?
a channel protein that controls flow of H20 and Cl ions.
How come you have varying severities of CF?
several different mutations can take place on CFTR causing differing defects
What are the different kinds of CFTR mutations?
Major-> protein doesnt fold properly (F508)
truncated proteins
proteins that dont utilize energy properly so degrade quickly
The most abnormal hemoglobin conditions are sickle cell anemia and (blank)
sickle beta thalassemia.
In sickle cell anemia and Beta thalassemia, how will newborns look>
look normal at birth but anemia develops w/in first few months followed by increased susceptibility to infection, slow growth rates, and life threatening splenic sequestration
SCD is dominant or recessive?
recessive
on the genetic level, why do you get sickle cell disease?
glutamine (hydrophilic and polar) is replaced by valine (hydrophobic and nonpolar) which makes hemoglobin less water soluble and can crystalilize under acidic conditions
(eventually fatal disease due to anemia and organ damage)
What kind of hemoglobin is found in individuals with SCD?
hemoglobin S (HBB gene mutation resulting in abnormal version of beta globin)
Besides HBB gene mutations creating hemoglobin s, what else can happen?
low levels of beta globin production resulting in beta thalassemia
How do you get congenital hypothyroidism?
What are the effects of this if untreated?
How can you prevent this adverse effect?
dont produce enough TH
mental retardation and stunted growth
Catch the disorder before 3 weeks of age and treat
How do you get thyroid hormone?
take an iodine off of T4
(blank) results from a deficiency in the enzyme need to metabolize galactose.
galactosemia
What is the guthrie test?
THe iit is the heal stick blood test on newborns to test for metabolic diseases
Protein function depends largely on the amino acids of which it is composed, and their precise (blank) .
order
Most phenotypic traits are produced by the interaction of what?
more than one gene and environment
What is this:
the sum of chemical processes through which food is converted into protoplasm and protoplasm is converted into smaller molecules and energy.
metabolism
What is deleted in many patients with CF?
F508 (phenylalanine)