Lethal defects- types and diagnosis/what are they?

Phe causes of lethal defects

Lethal defects are fatal defects(Latin: letalis-fatal). This means that developmental abnormalities developed during fetal life inevitably lead to the child’s death while still in pregnancy or to its death shortly after birth, despite implemented management or treatment. This is because despite their early detection, they are incurable.

Most often, lethal defects occur as a result of genetic disorders present in the child. Both abnormal cell divisions at the beginning of pregnancy or even earlier- during the division of male or female germ cells (gametes) contribute to their occurrence. These defects are referred to as chromosomal aberrations, meaning they are associated with an abnormal number of chromosomes in the child’s body. Then we have to deal with, among other things. with triploidy, tetraploidy (a triple or quadruple set of chromosomes) or trisomies (the presence of an extra chromosome in a pair).

Causes of lethal defects also include external agents: ionizing radiation or the effects of teratogenic drugs. In many situations, however, it is not possible to pinpoint the specific cause causing a lethal defect in a child. It is also common for pregnancies to die at an early stage, as these defects also cause miscarriages.

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Most common lethal defects

Among the lethal defects, the most commonly mentioned are diseases such as Edwards syndrome, Patau syndrome, renal agenesis, brainlessness and craniosynostosis, triploidy or sirenomelia (the so-called siren syndrome). Often these defects occur simultaneously, and the child develops disorders affecting several organs or systems.

Edwards syndrome

Trisomy of chromosomes of the 18th pair, or Edwards syndrome, is, along with Down syndrome, one of the most common birth defects associated with an abnormal number of chromosomes. Clinical signs in affected children include small face and ears, heart and kidney defects, mental retardation, and excessive muscle tension. More often, girls are born with Edwards syndrome.

Patau syndrome

Trisomy of chromosomes 13. couples, Patau syndrome, is listed as one of the most severe genetic defects in children.  Indeed, only 10% of children live to the age of one. Most often, this defect is associated with miscarriage or stillbirth. However, it is a disease whose symptoms can vary in severity. The most common symptoms of Patau syndrome include facial defects, finger defects, and intellectual disability.

Kidney agenesis

Agenesis of the kidneys, i.e. their failure to form, is one of the lethal defects, since a person without kidneys, due to their vital functions, has no chance of survival. Often a pregnancy with complete renal agenesis in the baby ends in miscarriage. This defect is most often diagnosed during ultrasound examinations, where the doctor observes thrombocytopenia in addition to the failure to see one or both kidneys. It is also worth knowing that in the case of partial kidney agenesis, i.e. when one kidney is missing, it is possible for a child to develop and function normally without any discomfort.

Brainless

Brainlessness, or anencephaly, is a lethal defect that involves the failure of a child’s brain structures to develop. It often occurs simultaneously with craniallessness. The causes of anencephaly are believed to include. the action of ionizing radiation, which is particularly dangerous in the first weeks of a child’s development, when the formation of the neural tube takes place.

Diagnosis of lethal defects

During pregnancy, every woman should have at least 4 mandatory ultrasound examinations. The first of these-so-called. Genetic ultrasound, between 11. a 14. week of pregnancy, aims to, among other things. Detecting the risk of chromosomal aberrations in the child. It should be performed together with a screening dual or combined test, where biochemical tests and risk factors present in the woman are analyzed in addition to the ultrasound. Low levels of PAPP-A and beta- HCG protein may be associated with Edwards and Patau Syndrome, and elevated beta- HCG levels may indicate Down Syndrome. Likewise for nuchal translucency, an increase of which may be associated with chromosomal aberrations. The most important thing, however, is to make a suspected diagnosis based on the entire set of tests performed, not just one measured value.

If, on the basis of the first trimester ultrasound and the double test, the risk of defects is found to be high, it is recommended to perform further tests-invasive tests such as amniocentesis to examine the fetal karyotype. And when the risk is intermediate, testing for free fetal DNA is now recommended.

Care of a child with a lethal defect

Early diagnosis allows Parents to prepare for childbirth, as well as get an idea of care options for their sick child. Nowadays, there are many different types of foundations or prenatal hospices that help prepare for, as well as cope with, the difficult diagnosis of a lethal defect in a child. In turn, after the birth, help is provided by home hospices that allow palliative care.  It is also important to remember that each case is different, and the same lethal defect does not necessarily produce identical symptoms in different people. For this reason, survival time and quality of life can vary in specific situations.