" down syndrome
Clinical phenotype
For further information: Down Syndrome Symptoms
The genetic anomaly that accompanies Down syndrome determines the characteristics of the syndrome, both directly and by influencing the functioning of genes located on other chromosomes. Consequently, there is a great individual variability in phenotypic and clinical manifestations. In addition to genetic factors. , many of the differences depend on the type of education received in the family, at school and in general in the environment that surrounds these people.
Patients with Down Syndrome have various psycho-physical anomalies of varying degrees (mild, medium or severe), with mental retardation and a higher incidence of some systemic diseases.
PECULIAR PHYSICAL CHARACTERISTICS: there are numerous phenotypic peculiarities that characterize subjects with Down syndrome; despite a certain individual variability, among the most common anomalies we remember: small skull with flattening at the occipital level, round face with a flattened profile, small and round ears with low insertion, short nose with flat root, sloping eyelids (oblique from the top below and from "outside to inside"), small mouth, small and irregular teeth, voluminous tongue furrowed with deep fissures, palms crossed by a single transverse groove, short fingers with clinodactyly of the fifth finger, muscular hypotonia at birth and laxity ligamentous.
PSYCHICAL ASPECTS: mental retardation is constantly present, ranging in degree from medium to mild, with a tendency to worsen with age. Patients with Down syndrome develop the neuropathological signs of Alzheimer's disease at a much earlier age than normal individuals
The life expectancy of people with Down syndrome has improved considerably over the past 50 years; according to the most recent data, in economically advanced countries it is about half a century, compared to 16 years in the "early 1950s" and 10 years in 1929.
Pregnancy screening test
The first screening method for trisomy 21, introduced in the early 1970s, was based on the association with maternal age. The risk of having a child with Down syndrome, in fact, increases with increasing age. maternal, according to the trend illustrated in the figure (below). Between the ages of twenty and thirty, therefore, the increase in risk is rather modest, while it becomes relevant after the age of thirty-five.
Below, we report a simple calculation module to quantify the theoretical risk of giving birth to a child with Down syndrome, in relation to maternal age.
Age of the mother
Bibliography: Estimating a woman "s risk of having a pregnancy associated with Down" s syndrome using her age - Cuckle, H., Wald, N & Thompson, S..
The relationship between maternal age and prevalence of Down syndrome at birth was almost comparable in different parts of the world.
Of course, science now has numerous tools at its disposal to better characterize this risk. The so-called "triple test", for example, is based on the assay of three markers in serum: alpha-fetoprotein, human chorionic gonadotropin and unconjugated estriol.
The risk of carrying a child with Down syndrome is considered high when the mother has high blood levels of inhibin A and human chorionic gonadotropin, associated with a reduction in those of estriol and alpha-fetoprotein.
The tests listed so far are carried out during the second trimester of pregnancy, generally between the fifteenth and twentieth week of gestation; even earlier tests, performed towards the end of the first trimester (11th - 13th week) include the measurement of the pregnancy-associated plasma protein A (PAPP-A) and the free fraction of the β-subunit of the hCG (free-βhCG), together with the "ultrasound examination of nuchal translucency.
Other invasive tests used for the early diagnosis of Down syndrome are the sampling of the chorionic villus (villocentesis), performed between the 9th and 14th week of gestation (risk of abortion 1%) and the taking of an umbilical blood sample by percutaneous (risk of abortion higher than other methods). Amniocentesis and chorionic villus sampling are generally performed in cases where the triple or quad test show a high risk of carrying fetuses with Down syndrome in the womb; despite the not negligible risk of abortion, in fact, these two tests have a "diagnostic accuracy close to 99%. This means that the use of these tests is on average able to identify 98 to 99 actual cases of Down syndrome out of 100.
For further information: nuchal translucency, PAPP-A, tri-test, combined pregnancy test.
Care and treatment
For further information: Drugs to treat Down Syndrome
The adoption of an early enabling intervention strategy is fundamental to fully exploit the psycho-physical development potential of children with Down syndrome. The contribution of the various associations present in the area is therefore of great help, which cannot however ignore a deep involvement of family members. Children with Down syndrome can learn - albeit to an extent that depends on the severity of their symptoms - to carry out the activities normally performed by other children, such as playing, talking, building, practicing sports, even if this requires learning times longer.
Other articles on "Down Syndrome: Screening and Testing in Pregnancy"
- Down syndrome
- Down Syndrome - Causes and Risk of Having an Affected Child
- Diet and Down Syndrome
- Medicines to Treat Down Syndrome
