Trisomy 18 and 13

What are trisomy 18 and trisomy 13?

三体术语描述了三个染色体而不是通常的染色体。例如，三体第21或唐氏综合症, occurs when a baby has three #21 chromosomes. Other examples are trisomy 18 and trisomy 13, fatal遗传性出生障碍。

• Trisomy 18 occurs in about one out of every 6,000 to 8,000 live births and trisomy 13 occurs in about one out of every 8,000 to 12,000 live births.
• It's characterized by severe mental retardation and health problems involving nearly every organ system of the body.
• 患有疾病的婴儿通常会在1岁时死亡，但有一些案例使孩子们生存到十几岁。
• 第18三体术也称为“爱德华氏综合症”，三体疾病也称为“ Patau综合征”，后者首先描述了这些疾病。

是什么导致第18和三体造成三体性？

Trisomy 18 and 13 are usually caused by spontaneous genetic mutations that occur at the time of fertilization. Normally, each egg and sperm cell contains 23 chromosomes. The union of these cells creates 23 pairs, or 46 total chromosomes, half from the mother and half from the father. Sometimes, an error occurs when an egg or sperm cell is forming, causing it to have an extra chromosome #18 or #13.

• When this cell contributes the extra chromosome 18 to the embryo, trisomy 18 results.
• 当这个细胞造成额外的13号染色体to the embryo, trisomy 13 results.

额外的18或13染色体可以来自母亲的卵细胞或父亲的精子细胞。

在某些情况下，额外的18或13染色体附着在鸡蛋或精子中的另一个染色体上。这称为易位，是可以遗传的第18或13三体三体的唯一形式。有时，父母可以携带“平衡”重排，其中18或13染色体附着在另一个染色体上。但是，由于父母没有任何额外或缺失的染色体材料，因此据说它们具有“平衡的易位”，通常是正常且健康的。

What types of problems do children with trisomy 18 and trisomy 13 typically have?

What is the risk of parents of a child with trisomy 18 or trisomy 13 having another child with trisomy 18 or 13?

The chance of having another baby with trisomy 18 or 13 is no more than 1 percent, although the risk increases slightly as the mother ages. The genetic test to diagnose trisomy 18 or 13 in a baby can determine the underlying chromosomal abnormality, which is important in determining a mother's risk in future pregnancies. Your doctor may refer you to a genetic physician or genetic counselor who can explain the results of chromosomal tests in detail, including recurrence risks.

我们如何诊断三体术和第三三体三体

Chromosomal abnormalities such as trisomy 18 and 13 can be diagnosed before birth by analyzing cells in the amniotic fluid (amniocentesis) or from the placenta.

• 胎儿超声在怀孕期间，还可以提供有关第18或13三体的可能性的信息，但是超声并不是100％准确的，因为某些三体三体和13的婴儿在超声波上可能与没有综合征的婴儿相同。
• 染色体分析，无论是在血液样本上进行的，来自羊水的细胞还是胎盘的细胞，精度都超过99.9％。

自从第18和三体三体三体分别具有独特的特征以来，医生可以简单地通过身体检查确定婴儿是否患有三体术或13。可以分析以确定额外的18或13染色体的存在。

目前无法治愈Trisomies 18和13。治疗是基于支持和管理症状的。实际上，许多患有这些疾病的婴儿可能不会生活在生命的头几天或几周之外。重要的是要讨论是使用生命支持措施还是其他医疗程序。

波士顿儿童医院的第18和13三体

围绕第18和13三体三体护理的决定是困难和个人的。您在波士顿儿童的医生可以将您与可用于在此期间提供支持和帮助的资源联系起来，包括早期干预服务，社会工作者，医院牧师或神职人员和遗传顾问。

Other families who have or have had a baby with trisomy 18 or trisomy 13 are particularly helpful and supportive, since they have experienced many of the same questions and emotions. We can help connect you to families who have faced similar situations.