About Trisomy 13 and 18
Mosaic trisomy is the presence of an extra chromosome in some cells, and a partial trisomy is when there is a part of an extra chromosome in all the cells. Sometimes the extra chromosomal material may be attached to another chromosome. This is called a translocation. Most of the clinical data that is available refers to full trisomy 13 and 18 and may be inappropriate when applied to children with other forms of these conditions. In addition, testing for mosiacism can produce inconsistent results depending on the type of sample used, (blood or skin). Doctors do not always know how well a child with mosaic trisomy will be until they grow older.
Survival of a baby with trisomy 13 or 18
Survival is difficult to predict as every baby born with trisomy 13 or 18 is unique. Many physicians quote 5-10% survival but the research from which this information is obtained seldom includes any information about the treatment provided to children. Survival seems to relate to the birth weight of a newborn, the number of medical issues present and the level of care that is provided to the baby. If a hospital or medical system has a protocol of inducing delivery early and limiting care to the newborn, it stands to reason that the baby will have at greater risk of having a very short life. When treatment (including surgery) was offered to a selected group of newborns in Japan whom physicians thought had a reasonable chance of being discharged home, over 40% of the children survived beyond one year.
Many believe that the survival rate for children born with trisomy 13 and 18 would be higher except for a self-fulfilling prophecy. This means that if physicians believe that a baby will die and any care provided (even oxygen or nutrition) only prolongs dying, he/she might limit or withhold care. Withholding certain care would ensure that many babies would die and thus the expectation or prophecy of death would be fulfilled.
Survival of babies with a prenatal diagnosis is known to be less than those with a post natal diagnosis. This might be due to the fact that most countries adopted the guidelines of the International Liaison Committee on Resuscitation which recommend that newborns with trisomy 13 and similar conditions should not be resuscitated at birth due to expectation of early death and unacceptable quality of life of survivors. Such a recommendation is unethical because quality of life is a determination that should be made by parents to enable them to make informed decisions on behalf of their children.
Recent research (Janvier, 2012) on a large number of surviving children revealed that despite their disability and the challenges in care, the children are happy, enrich their families, and parents believe they have a positive effect on siblings.
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