Chromosome abnormalities and pregnancy loss

Question 1

What percentage of pregnancies are lost after implantation?

Answer 1

About one-third

This statistic highlights the common occurrence of spontaneous pregnancy loss in humans.

Question 2

What is the leading known cause of pregnancy loss?

Answer 2

Chromosome abnormalities

Chromosome abnormalities significantly contribute to early pregnancy loss.

Question 3

What is the estimated percentage of conceptions that have a chromosome abnormality?

Answer 3

10% to 20%

This indicates a substantial occurrence of chromosomal issues at conception.

Question 4

What percentage of chromosomally abnormal conceptions are lost before term?

Answer 4

At least 95%

This statistic emphasizes the critical impact of chromosome abnormalities on pregnancy outcomes.

Question 5

What are the three most common types of chromosome abnormalities found in miscarriages?

Answer 5

• Trisomies (about 50%)
• Monosomies (20%)
• Triploids (15%)

These percentages reflect the distribution of chromosome abnormalities identified through karyotype studies.

Question 6

What is the most common trisomy at conception that is never seen in live births?

Answer 6

Trisomy 16

Trisomy 16 often results in early pregnancy loss and is not viable for live birth.

Question 7

What percentage of oocytes have missing or extra chromosomes according to karyotype studies?

Answer 7

20% to 25%

This finding indicates a significant prevalence of chromosomal anomalies in female gametes.

Question 8

What is the frequency of aneuploidy in human sperm cells?

Answer 8

About 3% to 4%

This statistic underscores the relevance of sperm chromosome abnormalities in fertility issues.

Question 9

What percentage of sperm cells are found to have structural abnormalities?

Answer 9

5%

Structural abnormalities in sperm can contribute to reproductive challenges and pregnancy loss.

Question 10

True or False: The sperm cells studied in human–hamster hybrids represent a complete sample of sperm cells.

Answer 10

False

The study only includes sperm cells capable of penetrating the hamster oocyte, which may not represent the entire population.

Question 11

What technique allows for rapid evaluation of aneuploidy in many cells?

Answer 11

FISH analysis

FISH analysis offers advantages over traditional methods, yielding similar results in evaluating chromosome abnormalities.

Question 12

What is the average frequency of disomy for autosomes as found in FISH studies?

Answer 12

Approximately 0.15%

This statistic illustrates the occurrence of disomy among human chromosomes.

Question 13

Fill in the blank: The incidence of chromosome abnormalities increases with _______.

Answer 13

Advanced paternal age

Advanced paternal age is associated with a higher rate of chromosomal issues in sperm.