Question

A young couple comes to your office with concerns about miscarriage. They have heard stories about how a person can suddenly lose her pregnancy, and they want to know as much as they can about the subject. They mention something about extra chromosomes and want to know what that means. Which of the following karyotypes represents triploidy? A. \(47 \mathrm{XXX}\) B. \(48 \mathrm{XXX}\) C. \(69 \mathrm{XXX}\) D. 92 XXXX

Short answer

C: 69 XXX

Step-by-step solution

Understand the Problem

The task is to identify which of the given karyotypes represents triploidy. Karyotypes describe the number and appearance of chromosomes in the nucleus of a cell.

Define Triploidy

Triploidy is a chromosomal abnormality where an individual has three copies of each chromosome instead of the normal two. Humans normally have 46 chromosomes (23 pairs), so a triploid individual would have 69 chromosomes (3 sets of 23).

Analyze Each Option

Examine the karyotype options to determine which one has 69 chromosomes: A. 47 XXX - This karyotype has 47 chromosomes, which is not triploidy. B. 48 XXX - This karyotype has 48 chromosomes, which is not triploidy. C. 69 XXX - This karyotype has 69 chromosomes, which matches triploidy. D. 92 XXXX - This karyotype has 92 chromosomes, which is not triploidy.

Conclude Triploidy Karyotype

Based on the analysis, the karyotype that represents triploidy is option C: 69 XXX.

Key concepts

Karyotype Analysis

Karyotype analysis is a method used to examine an organism's complete set of chromosomes. It's typically performed using a sample of cells, such as blood or amniotic fluid. The chromosomes are stained and viewed under a microscope to look for any abnormalities in number or structure.

In a standard human karyotype, you'll see 46 chromosomes, arranged in 23 pairs. Each pair consists of one chromosome from the mother and one from the father.

This type of analysis helps in diagnosing chromosomal abnormalities like Down syndrome (trisomy 21), Klinefelter syndrome (47, XXY), and Turner syndrome (45, XO).

Chromosomal Abnormalities

Chromosomal abnormalities occur when there is a change in the number or structure of chromosomes. These changes can result in health issues or developmental delays.

Abnormalities can be either numerical or structural:

• Numerical Abnormalities: These are changes in the number of chromosomes. For example, having an extra chromosome 21 causes Down syndrome.
• Structural Abnormalities: These involve changes in the shape or content of the chromosome. Examples include deletions, duplications, or translocations of chromosome segments.

Chromosomal abnormalities often lead to miscarriages because the embryo can't develop properly. This is why understanding these abnormalities is crucial for couples facing recurrent pregnancy loss.

Miscarriage Causes

Miscarriages can be caused by various factors, but chromosomal abnormalities are among the most common reasons. When an embryo has the wrong number of chromosomes, it often can't develop normally, leading to miscarriage.

• Chromosomal Abnormalities: These account for about 50-70% of all miscarriages. An imbalance in the chromosomal number makes it difficult for the embryo to survive.
• Maternal Health Issues: Conditions like diabetes, thyroid disease, or infections can contribute to miscarriage.
• Lifestyle Factors: Smoking, excessive alcohol consumption, and drug use raise the risk of miscarriage.

Knowing the cause of miscarriage helps healthcare providers recommend appropriate interventions and options.

Human Chromosome Number

Humans typically have 46 chromosomes, making up 23 pairs. These chromosomes contain the DNA that guides our growth, development, and bodily functions.

The 23 pairs include 22 pairs of autosomes and one pair of sex chromosomes. Autosomes look the same in both males and females, while the sex chromosomes differ. Females have two X chromosomes (XX), and males have one X and one Y chromosome (XY).

Abnormalities in chromosome number can lead to developmental issues. For example, Trisomy 21 (an extra 21st chromosome) causes Down syndrome, while triploidy results in 69 chromosomes due to an extra set of all chromosomes. These conditions often have significant effects on an individual's health and development.