Genetics Flashcards
What is Kleinfelter’s syndrome?
Karyotype 47, XXY
Two X’s in males
What is the cause of Kleinfelter’s syndrome?
IT IS NOT INHERITED
One extra copy of the X chromosome in each cell (XXY), the most common cause
An extra X chromosome in some of the cells (mosaic Klinefelter syndrome), with fewer symptoms
More than one extra copy of the X chromosome, which is rare and results in a severe form
What are the symptoms of Klinefelter’s syndrome?
- Often taller than average
- Lack of secondary sexual characteristics
- Small, firm testes
- Infertile
- Gynaecomastia - increased incidence of breast cancer
- Elevated gonadotrophin levels but low testosterone
How do you diagnose Kleinfelter’s syndrome?
Karyotype
What is the treatment for Klinefelter’s syndrome?
- Testosterone replacement therapy
- Breast tissue removal
- Speech and physical therapy
- Educational evaluation and support
- Fertility treatment
- Psychological counseling
WHAT IS TUNER’S SYNDROME?
X chromosomes (sex chromosomes) is missing or partially missing
A girl with Turner syndrome only has one normal X sex chromosome, rather than the usual two.
What are the causes of Turners syndrome?
Monosomy
The complete absence of an X chromosome
Mosaicism
This results in some cells in the body having two complete copies of the X chromosome
X chromosome abnormalities
Abnormal or missing parts of one of the X chromosomes can occur
Y chromosome material
What are the symptoms of Turners syndrome?
What age is it diagnosed?
- Shorter than average
- Underdeveloped ovaries
- Shield chest, widely spaced nipples
- Webbed neck
- Bicuspid aortic valve (15%), coarctation of the aorta (5-10%)
- Primary amenorrhoea
Diagnosed
8 - 14 years old
How do you diagnose Turners syndrome?
Hormone levels?
What body?
- Raised FSH and LH
- Low oestrogen
- Demonstration of the 45,XO karyotype is confirmatory, as is absence of the Barr body
What is the treatment of Turners Syndrome?
- Growth hormone - increase height
- Oestrogen therapy - promote breast development and increase uterus size
What is Downs syndrome?
Down syndrome is a genetic disorder caused when abnormal cell division results in an extra full or partial copy of chromosome 21
What is the cause of Down syndrome?
NOT INHERITED
Trisomy 21
About 95 percent of the time, Down syndrome is caused by trisomy 21 — the person has three copies of chromosome 21
Mosaic Down syndrome
In this rare form of Down syndrome, a person has only some cells with an extra copy of chromosome 21
Translocation Down syndrome
Down syndrome can also occur when a portion of chromosome 21 becomes attached (translocated) onto another chromosome, before or at conception
What are the symptoms of Down syndrome?
- Flattened face
- Small head
- Short neck
- Protruding tongue
- Upward slanting eye lids (palpebral fissures)
- Unusually shaped or small ears
- Poor muscle tone
- Broad, short hands with a single crease in the palm
- Relatively short fingers and small hands and feet
- Excessive flexibility
- Tiny white spots on the colored part (iris) of the eye called Brushfield’s spots
- Short height
What are the complications of Down syndome?
Heart defects
Dementia
GI defects
Hypothyroidism
How do you diagnose Down syndrome?
First trimester
Blood test
Plasma protein-A (PAPP-A)
Human chorionic gonadotropin (HCG)
Ultrasound
- Nuchal translucency test - specific area on the back of your baby’s neck
- Double stomach bubble - duodenal atresia
- Short femur
Second trimester
The quad screen measures your blood level of four pregnancy-associated substances: alpha fetoprotein, estriol, HCG and inhibin A.
Chrionic villus sampling
Amniocentesis
What is the treatment for Down syndrome?
- Primary care pediatrician to coordinate and provide routine childhood care
- Pediatric cardiologist
- Pediatric gastroenterologist
- Pediatric endocrinologist
- Developmental pediatrician
- Pediatric neurologist
- Pediatric ear, nose and throat (ENT) specialist
- Pediatric eye doctor (ophthalmologist)
- Audiologist
- Speech pathologist
- Physical therapist
- Occupational therapist
What is Edward’s syndrome?
Edwards’ syndrome, also known as trisomy 18, is a rare but serious condition.
Edwards’ syndrome affects how long a baby may survive. Sadly, most babies with Edwards’ syndrome will die before or shortly after being born.
What is the cause of Edward’s syndrome?
- 3 copies of chromosome number 18 instead of 2.
- Having 3 copies of chromosome 18 usually happens by chance, because of a change in the sperm or egg before a baby is conceived.
What are the different types of Edwards’ syndrome?
Full Edwards’ syndrome
Mosaic Edwards’ syndrome
Partial Edwards’ syndrome
What are the symptoms of Edwards’ syndrome?
- Micrognathia
- Low-set ears
- Rocker bottom feet
- Overlapping of fingers
How is Edward’s syndrome diagnosed?
Think pregnancy
-
First trimester
- Blood test
- Plasma protein-A (PAPP-A)
- Human chorionic gonadotropin (HCG)
- Nuchal translucency test
-
Second trimester
- Alpha fetoprotein
- Estriol
- HCG
- Inhibin A.
- Chrionic villus sampling
- Amniocentesis
What is the treatment for Edwards’ syndrome?
The major cause of death in many of these infants is sudden death due to neurological instability, cardiac failure, and respiratory failure
Treatment for infants who survive past this is mainly aimed at complications of the disease
What is Patau’s syndrome?
Patau’s syndrome is a serious rare genetic disorder caused by having an additional copy of chromosome 13 in some or all of the body’s cells. It’s also called trisomy 13.
13 Tau units
What is the cause of Patau’s syndrome?
NOT INHERITED
What are the symptoms of patau’s syndrome?
- Microcephalic, small eyes
- Cleft lip/palate
- Polydactyly
- Scalp lesions
How do you diagnose Patau’s syndrome?
First trimester
Blood test
This blood test measures the levels of pregnancy-associated plasma protein-A (PAPP-A) and the pregnancy hormone known as human chorionic gonadotropin (HCG)
Nuchal translucency test
During this test, an ultrasound is used to measure a specific area on the back of your baby’s neck
Second trimester
The quad screen measures your blood level of four pregnancy-associated substances: alpha fetoprotein, estriol, HCG and inhibin A.
Chrionic villus sampling
Amniocentesis
What is the treatment for Patau’s syndrome?
- Normally do not live long after birth
- For the small number of babies with Patau’s syndrome who survive beyond the first few days of life, their care will depend on their specific symptoms and needs.
What is fragile X syndrome?
Fragile X syndrome (FXS) is a genetic disorder characterized by mild-to-moderate intellectual disability
The average IQ in males is under 55, while about two thirds of females are intellectually disabled