Down syndrome (DS) is one of the most frequent congenital birth defects, and the most common genetic cause of mental retardation. In most cases, DS results from the presence of an extra copy of chromosome 21 . DS has a complex phenotype, and a major goal of DS research is to identify genotype–phenotype correlations.
What is the genotype of Klinefelter syndrome?
In Klinefelter syndrome, the person has an extra X chromosome which results in three sex chromosomes (2X chromosomes and a Y chromosome). This results in a genotype of 44 + XXY or 47 chromosomes . – Klinefelter syndrome occurs due to a random error that causes a male to be born with an additional sex chromosome.
Which is the genotype of Down syndrome?
Regular trisomy 21 – also known as standard or free trisomy 21 – in which all the cells have an extra chromosome 21. Around 94% of people with Down’s syndrome have this type. Translocation – in which extra chromosome 21 material is attached to another chromosome. Around 4% of people with Down’s syndrome have this type.
Is Down syndrome XXY?
Several major chromosomal syndromes with altered numbers of chromosomes were reported, such as Down syndrome (trisomy 21 ), Turner syndrome (45,X) and Klinefelter syndrome (47,XXY).
What is the category of Down syndrome?
The three basic types of Down syndrome are trisomy 21, translocation, and mosaicism . All types of Down syndrome result from irregular chromosomes in some or all of the baby’s cells. These irregularities are caused by abnormal cell division, usually in the egg but sometimes in the sperm, before or after conception.
Can a Down syndrome child look normal?
People with Down syndrome all look the same . There are certain physical characteristics that can occur. People with Down syndrome can have all of them or none. A person with Down syndrome will always look more like his or her close family than someone else with the condition.
Can Down syndrome be prevented?
There’s no way to prevent Down syndrome . If you’re at high risk of having a child with Down syndrome or you already have one child with Down syndrome, you may want to consult a genetic counselor before becoming pregnant.
What is the life expectancy of a person with Klinefelter syndrome?
According to research, Klinefelter syndrome can shorten your life expectancy up to two years . However, you can still live a long, full life with this condition. The earlier you get treatment, the better your outlook will be.
CAN XXY have babies?
It is possible that an XXY male could get a woman pregnant naturally . Although sperm are found in more than 50% of men with KS 3 , low sperm production could make conception very difficult.
What gender is someone with XXY?
A person’s biological sex is determined by the sex chromosomes: females have two X chromosomes, or XX; most males have one X chromosome and one Y chromosome, or XY. Males with XXY syndrome are born with cells that have an extra X chromosome, or XXY.
What are the 3 types of Down syndrome?
- Trisomy 21. This is by far the most common type, where every cell in the body has three copies of chromosome 21 instead of two.
- Translocation Down syndrome. In this type, each cell has part of an extra chromosome 21, or an entirely extra one. ...
- Mosaic Down syndrome.
How can you tell a baby has Down syndrome?
- flat facial features.
- small head and ears.
- short neck.
- bulging tongue.
- eyes that slant upward.
- atypically shaped ears.
- poor muscle tone.
Is Klinefelter syndrome like Down syndrome?
Down’s syndrome has its own dysmorphic findings and is accompanied by mental retardation and hypotonia. Klinefelter’s syndrome is a syndrome caused by a numerical abnormality that affects male physical and cognitive development. This case reports a unique finding of 48,XXY, + 21 and a current literature review.
Can you tell if a baby has Down syndrome in an ultrasound?
An ultrasound can detect fluid at the back of a fetus’s neck , which sometimes indicates Down syndrome. The ultrasound test is called measurement of nuchal translucency.
What are signs of Down syndrome on ultrasound?
Certain features detected during a second trimester ultrasound exam are potential markers for Down’s syndrome, and they include dilated brain ventricles, absent or small nose bone, increased thickness of the back of the neck, an abnormal artery to the upper extremities , bright spots in the heart, ‘bright’ bowels, mild ...
Who is most likely to get Downs?
Causes and Risk Factors
One factor that increases the risk for having a baby with Down syndrome is the mother’s age. Women who are 35 years or older when they become pregnant are more likely to have a pregnancy affected by Down syndrome than women who become pregnant at a younger age.
