Seminario 19 Anomalias Cromosomicas Estructurales - Roxana Cerretini

Seminar 20. Balanced and unbalanced structural chromosomal abnormalities. Production mechanism.

The overall frequency of total chromosomal abnormalities in live newborns is one in every 150 live births, or 0.67%. In turn, the frequency of structural chromosomal abnormalities in live newborns is approximately 0.27%, or one in every 375 live births.

In turn, the frequency of total chromosomal abnormalities in stillbirths, stillbirths being fetuses that die after 20 weeks of gestation, is significantly higher between 5 and 10% of stillbirths. And the frequency of structural chromosomal abnormalities in stillborn infants is 2 to 5%.

Birth defects are defined as any structural, functional or biochemical abnormality existing at birth, regardless of whether it is detected at birth or not. Congenital defects are the most important cause of infant morbidity and mortality . The frequency of structural chromosomal abnormalities in newborns with congenital defects varies according to the type of defect and the diagnostic technology

used, but it is between 2 and 10% of the total cases. We see that approximately 10% of birth defects are due to chromosomal abnormalities.

Therefore, chromosomal abnormalities are responsible for a significant proportion of genetic diseases and may be suspected in a wide variety of clinical situations. So, as we already said, approximately the incidence of chromosomal abnormalities in total live newborns is between 0.5 and 1%. Here we have a normal human karyotype that is systematically arranged by chromosome size, number, and