Triploidy is a chromosomal disorder that is regarded as a nightmare for expecting parents. Read on to know what is Triploidy syndrome and learn more about this rare disease.
What is Triploidy Syndrome?
It is a rare disorder in which a baby is born with 69 chromosomes instead of 46. Most people are born with two sets of 23 chromosomes, or 46 chromosomes in total. People with Triploidy birth condition have an extra set of chromosomes in their body. A greater amount of chromosomes can lead to many birth defects and result in many developmental problems. In worse cases, this condition may even lead to death.
It is known by various other names like :
- Triploidy Syndrome
- Diploid/Triploid Mixoploidy
- 3n Syndrome
- 2n/3n Mixoploidy
- Chromosome Triploidy Syndrome
Medical studies have not been able to identify any cause for this disease. It is difficult to say why Triploidy occurs in infants of seemingly healthy adults. The disease does not arise due to any physical defect in any of the parents. Old age is often regarded to be a cause for this condition. But medical research has denied that the disease has got anything to do with advanced age in parents.
Triploidy has not been found to have any preference towards gender, age or any other physical factors. Genetic factors do not seem to have any association with this disease. Family members and relations of Triploidy couples are found to give birth to normal offspring.
Triploidy Syndrome Symptoms
Babies with Triploidy condition are usually born in any of these abnormal ways.
In this condition, a sperm with two sets of chromosomes fertilizes the egg.
The egg is fertilized with two sperms in Dispermy, which is a kind of Diandry. The fetus is found to have a single set of maternal chromosomes and a double set of paternal chromosomes in both types of Diandry.
The egg-farming cells fail to properly separate which results in two sets of chromosomes in the fertilized egg. The baby is seen to have a single set of the father’s chromosomes and two sets of the mother’s chromosomes.
In Diandric Pregnancies, mothers are seen to have a bigger placenta. The infant is generally of a healthy build but expect mothers are in the risk of suffering a miscarriage while in the third trimester of pregnancy. Mothers in Digynic pregnancies tend to have a smaller placenta. The physical development of Triploidy baby is severely restricted due to this. The mother usually suffers a miscarriage in the second trimester.
Causes of Triploidy Extra Chromosome
In Triploidy, 69 chromosomes are supposed to form in various ways. Extra set of chromosomes from father occurs due to failure of cell division in Spermatocyte in Meiosis 1 or 2. Additional maternal chromosome set develops due to failure of cell division in Oocyte in Meiosis 1 or 2. Dual fertilization of the ovum with double sperms, as in Dispermy, may also cause Triploidy.
Miscarriages are common in case of Triploidy. Babies affected with this disease usually die during early miscarriage. As aforesaid, miscarriages usually occur in the second or third semester of pregnancy.
Couples can expect a normal delivery while giving birth to a Triploidy baby. Many infants suffer from breathing difficulties after birth and need oxygen support to survive. However, some babies can breathe well and do not need any support.
Babies have been found to be born despite Triploidy. While some infants have several birth defects and survive only for 4-5 months, some manage to live on. Those that manage to survive usually suffer from a variation of Triploidy known as Mosaic Triploidy Syndrome. Babies with this condition have the same 46 chromosomes as normal people but have an extra set of chromosomes in only a few cells.
Babies with classic cases of Triploidy condition usually live anywhere from a few hours to a few months. Medical history reports only one baby who lived for around ten months with this disorder. This is, however, a rare case. Most pregnancies affected by Triploidy result in a miscarriage within the first trimester.
This disorder arises in as many as 2,500 live births and about 2% conceptions. Most infants are lost through miscarriages. Triploidy during pregnancy accounts for around 20% of total abortions done due to abnormal chromosomal defects.
Is Triploidy Lethal?
The disorder is generally deadly for infants. It may lead to miscarriage in the second or third semester and birth of stillborn babies. It also results in spontaneous cases of abortion. Mosaic Triploidy Babies may survive longer but are frequently seen to suffer from mental retardation.
How Is Triploidy Diagnosed?
Triploidy Diagnosis is generally done with the aid of Ultrasound scans, blood tests and Amniocentesis.
Triploidy On Ultrasound
In Triploidy Ultrasound findings help determine the physical measurements of the infant. Inhibited growth is usually suggestive of Triploidy symptoms.
Blood examinations conducted during the first semester show low PAPP-A levels and high AFP and hCG levels in Diandric pregnancies. In Digynic Triploidy hcg levels and PAPP-A levels are low. AFP levels can vary from low to normal.
Triploidy is often diagnosed by examining small cell samples from the growing placenta.
Triploidy karyotyping is the most definite way of diagnosing the condition. Karyotype refers to the chromosomal appearance of somatic cells in living beings. This includes the size, structure, arrangement and number of chromosomes. Karyotype examination is mainly done through two methods, Amniocentesis and Chorionic Villi Sampling (CVS).
Chorionic Villi Sampling (CVS)
In this method, a sample of tissue from the fetus is removed with the aid of a fine needle or a catheter. Both placenta and fetus develop from the same fertilized egg. Naturally, the number of chromosomes in the placenta can give an indication about the fetal chromosomal quantity.
A hollow needle is passed into the body of the expecting mother and a small sample of the amniotic fluid surrounding the infant is taken out. This fluid consists of cells exuviated by the fetus. Test reveals the number of chromosomes in cells. Any abnormality in chromosomal count helps detect Triploidy.
Is It Rare?
Triploidy is a rare disease. It is said to affect between one and three percent of pregnancies every year.
The risk of having a Triploidy pregnancy is very rare. It is only in very rare cases that families with one Triploidy miscarriage suffer another. Repeated Triploidy pregnancies only occur by chance. For a woman who has once had Triploidy recurrent miscarriage is a remote possibility.
Why Is It Lethal?
The presence of more amounts of chromosomes gives rise to severe developmental defects in placenta and the fetus. The placenta may be unusually big or small in size thus affecting the fetal development. Even if the baby is born, it may suffer from breathing difficulties in future.
This medical syndrome has no definite treatment. The condition cannot be prevented in any way. However, Triploidy termination is possible by terminating the pregnancy. A woman can try pregnancy after Triploidy loss once her urine and blood test results suggest normalcy.
Triploidy and Cancer
Triploidy may give rise to cancerous conditions in mothers. It should be checked that there is no unusual molar tissue left in women on who had a molar pregnancy. Remaining traces of molar tissue in women can have the risk of developing into Choriocarcinoma, a type of cancer. Choriocarcinoma is completely curable. It should be seen that the condition is diagnosed and treated early. Early treatment of the disease makes patients recover faster from it.
Triploidy and Polyploidy
Triploidy is the condition in which more than three sets of different chromosomes are present. Polyploidy is a disease that is characterized by the presence of more than three sets of chromosomes in the fetus.
Triploidy Blood Pressure
Women with Triploidy pregnancy often suffer from Hypertension or an increase in blood pressure. There can be headaches, blurred vision, dizziness and other discomforting symptoms because of this. In Triploidy Hypertension is a serious symptom and may severely affect the health of a woman.
Triploidy Down Syndrome
According to a medical research, a large percentage of Triploidy population is at a higher risk of suffering from Down’s Syndrome. Down’s Syndrome is a congenital disease caused due to the presence of the extra 21st chromosome. This disorder leads to birth defects like short stature, flat face and mental abnormality.
Triploidy Partial Molar Pregnancy
Partial Molar Pregnancy is a condition in which the placenta gets enlarged like a cyst and has an appearance similar to a bunch of grapes. Women who have had a Partial Molar Pregnancy along with Triploidy should be thoroughly examined to check for any abnormal tissues. As aforementioned, presence of unusual tissues may result in cancer.
Written by anirudh
on June 1st, 2011. The article was last updated on August 30th, 2011