Lecture 19 Flashcards
what is newborn screening?
a non-invasive test that allows for the identification of different diseases in the first hours after birth - screening not diagnostic test
what is the newborn screening performed on?
on an absorbent paper called Guthrie test (named after the doctor who carried out the first screening for Phenylketonuria)
name the 10 criteria for the inclusion of the pathologies analyzed in the panel:
- disease is a major public health problem
- effective treatment is available
- we know how to treat the disease
- the condition is recognizable and pre-symptomatic
- test is able to detect the pathological condition
- is non-invasive
- history and progression of the disease is known
- protocol for treatment is clear
- cost of test is balanced by the overall cost of the disease
- screening is systematic h
how many diseases are included in the screening panel in Italy?
49
what are the major pathologies included in the panel?
cystic fibrosis, hypothyroidism, phenylketonuria, and other congenital defects of intermediate metabolism (when we have alterations of the metabolism of a specific protein, for which we can treat by substituting the deficiency, allowing for an amelioration of the prognosis and avoidance of severe symptoms), and rare diseases (10% of total pathologies tested for) most of which are homozygous recessive
what is the goal of newborn screening?
to detect fatal conditions as early as possible before the baby shows signs of symptoms of the disease, allowing a prompt therapeutic treatment
if prompt treatment is not administered, what can happen?
the majority of cases if untreated can cause permanent damage to the CNS and can lead to intellectual disability or development disabilities
how is newborn screening performed?
- a drop of blood is collected from the heel and put onto the absorbent paper
- card is taken to the reference laboratory where it is used for the screening panel
not all hospitals have reference labs for screening, so sometimes it takes a few days to get results
what occurs in the event of a positive test?
a confirmative test must be performed
what is a downside to the newborn screening test, particularly in regards to the parents?
there can be a negative psychological impact on the parents if the baby is positive, but requires further investigation before the diagnosis can actually be confirmed
what is phenylketonuria?
a rare inherited metabolic disorder - autosomal recessive disorder that is caused by mutations on genes encoding for liver enzyme (PAH: phenylalanine hydroxylase) that is necessary for the metabolism of phenylalanine and essential amino acids contained in food, as well as fundamental for the building of proteins
what happens if we have a PAH deficiency?
there is an increase in the concentration of phenylalanine in the blood that can be toxic, especially for the brain, causing compromised brain function leading to alterations and disability
what does the PAH gene do in a healthy person?
converts phenylalanine into tyrosine
what occurs PKU?
PAH is not present to phenylalanine is not converted and accumulates in the peripheral blood with toxic effects
what are the main symptoms of PKU?
intellectual disability, microencephaly, motor deficits, eczematous rash, autism spectrum disorder, developmental delays, growth deficit, aberrant behaviors, and psychiatric symptoms (all related to the CNS)
