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

What is the cause of fragile X syndrome?
Mutation of the fragile X mental retardation 1 (FMR1) gene on the X chromosome
Increase in the number of CGG trinucleotide repeats
What are the symptoms of fragile X syndrome?
- Intellectual disability
- Long and narrow face
- Large ears
- Flexible fingers
- Large testicles

How do you diagnose fragile X syndrome?
Genetic testing
What is the management for fragile X syndrome?
- No specific cure
- Services can include therapy to learn to talk, walk, and interact with others
What is cycstic fibrosis?
Cystic fibrosis (CF) is an inherited disorder that causes severe damage to the lungs, digestive system and other organs in the body.
What is the cause of cystic fibrosis?
In cystic fibrosis, a defect (mutation) in a gene — the cystic fibrosis transmembrane conductance regulator (CFTR) gene — changes a protein that regulates the movement of salt in and out of cells
What are the symptoms of cystic fibrosis?
Respiratory signs and symptoms
A persistent cough that produces thick mucus (sputum)
Wheezing
Exercise intolerance
Repeated lung infections
Inflamed nasal passages or a stuffy nose
Recurrent sinusitis
Digestive signs and symptoms
Foul-smelling, greasy stools
Poor weight gain and growth
Intestinal blockage, particularly in newborns (meconium ileus)
Chronic or severe constipation, which may include frequent straining while trying to pass stool, eventually causing part of the rectum to protrude outside the anus (rectal prolapse)
What are the complications of cystic fibrosis?
- Bronchiectasis
- Diabetes
- Infertility
- Liver disease
- Osteoporosis
- Cor pulmonale
How do you diagnose cystic fibrosis?
-
Sweat test
- Patient’s with CF have abnormally high sweat chloride
- Normal value < 40 mEq/l, CF indicated by > 60 mEq/l
What is the treatment for cystic fibrosis?
Preventing and controlling infections that occur in the lungs
Removing and loosening mucus from the lungs
Chest physical therapy
Nebulisers
Treating and preventing intestinal blockage
Providing adequate nutrition
High calorie diet, including high fat intake
What is myotonic muscular dystrophy?
Muscular dystrophy is a group of diseases that cause progressive weakness and loss of muscle mass.
In muscular dystrophy, abnormal genes (mutations) interfere with the production of proteins needed to form healthy muscle.
What is the cause of myotonic muscular dystrophy?
Autosomal Dominant Chromosome 19
What are the symptoms of myotonic muscular dystrophy?
In the face:
- Frontal baldness
- Myopathic face with ptosis, hanging jaw, wasting of muscles of masticatio
- Cataracts in 80% of cases
In the limbs:
- Characteristic is the inability of the patient to let go of the examiner’s hand when they shake hand
- Percussion myotonia - via tapping over the thenar eminence - may result in contraction and slow relaxation of opponens pollicis
- Wasting and weakness distally
How do you diagnose myotonic muscular dystrophy?
- Slightly raised CPK enzyme levels
- Conduction abnormalities on ECG
- Characteristic myopathic EMG, with so-called dive bomber noise
- Cataracts may be seen by slit lamp examination
- If urinary glucose is positive, it is followed by glucose tolerance test to confirm diabetes
What is the management for myotonic muscular dystrophy?
Membrane stabilisers to reduce myotonia, including procainamide, phenytoin, quinine, quinidine, acetazolamide
Identification and treatment of cataracts and diabetes mellitus
Genetic counselling
Avoiding sedative drugs as sensitivity is increased
What is duchenne muscular dystrophy?
Duchenne muscular dystrophy is a common and possibly the best known muscular dystrophy. It follows an aggressive and progressive course.
What is the cause of duchenne muscular dystrophy?
X-linked disease
Xp21
What are the symptoms of duchenne muscular dystrophy?
- Dilated cardiomyopathy
- Delayed walking - after 18 months
- Not running by age 3
- lordotic waddling gait
- Gower’s sign
- Weakness is symmetrical
- Wasting of most muscles but pseudohypertrophy of the calves
- Episodes of myoglobinuria (cola coloured urine)
- ALT or AST High
- Learning difficulties and behavioural issues
- Speech and language delay
- Autistic spectrum disorder
What are the investigations for duchenne muscular dystrophy?
- Genetic testing has now replaced muscle biopsy as the way to obtain a definitive diagnosis
- Serum creatine kinase 30 to 200 times higher than normal
What is the management for duchenne muscular dystrophy?
- Corticosteroids - improve muscle function and prolong ambulation, stop cardiac and lung disease
- Walking aids
- Prophylatic ACEI - high survival and lower hospitalisaiton
- Surgery to cut tendons and prevent disabiling contractures
What is Angelman’s syndrome?
Angelman syndrome is a genetic condition that affects the nervous system and causes severe physical and learning disabilities

What is the cause of Angelman’s syndrome?
Deletion of maternal chromosome 15
What are the symptoms of Angelman’s syndrome?
Severe mental retardation without speech
Microcephaly
Flat occiput - brachycephaly
Jerky ataxic movements with broad based gait
Smiling face
Gales of inappropriate laughter

How do you diagnose Angelman’s syndrome?
-
Clinically
Problems with movement and balance, a small head size, flatness in the back of the head, and frequent laughter -
Parental DNA pattern
This test, known as a DNA methylation test, screens for three of the four known genetic abnormalities that cause Angelman syndrome. -
Missing chromosomes
A chromosomal microarray (CMA) - Gene mutation
What is the treatment for Angelman’s syndrome?
Anti-seizure medication to control seizures
Physical therapy to help with walking and movement problems
Communication therapy, which may include sign language and picture communication
Behavior therapy to help overcome hyperactivity and a short attention span and to aid in development
What is Prader-Willi syndrome?
Prader-Willi syndrome is a rare genetic condition that causes a wide range of physical symptoms, learning difficulties and behavioural problems.
It’s usually noticed shortly after birth.

What is the cause of Prader-Willi syndrome?
Prader-Willi syndrome is a genetic disorder, a condition caused by an error in one or more genes
Problem lies in the genes located in a particular region of chromosome 15
What are the symptoms of Prader-Willi syndrome?
- Hypotonia
- Hypogonadism
- Obesity
How do you diagnose Prader-Willi syndrome?
Genetic testing
What is the treatment for prader-willi syndrome?
- Good nutrition + weight management
- Human growth hormone treatment
- Sex hormone replacement
What is Noonan syndrome?
Defective gene on chromosome 12

What is the cause of noonan syndrome?
Inherited
Children who have one parent with Noonan syndrome who carries the defective gene (autosomal dominant) have a 50 percent chance of developing the disorder.
Random
Noonan syndrome can develop because of a new mutation in children who don’t have a genetic predisposition for the disorder (de novo).
What are the symptoms of noonan syndrome?
- Webbed neck
- Pectus excavatum
- Short stature
- Pulmonary stenosis

How do you diagnose noonan syndrome?
Hard to identify
May not be until adulthood until it is diagnosed
What is the treatment for noonan syndrome?
- Heart treatment
- Treating low growth rate
- Addressing learning difficulties
- Vision and hearing treatments
- Treatment for bleeding and bruising
WHAT IS WILLIAMS SYNDROME?
Abnormal development of the neural crest
Leading to a typical elfin facies and hypercalcaemia caused by gastrointestinal calcium absorption.
Will-i-am A THE 7TH CALCIUM ELF

What is the cause of Williams syndrome?
Williams syndrome is caused by a deletion, or missing piece, of a region on chromosome 7
What are the symptoms of Williams syndrome?
Elfin-like facies
Characteristic like affect - very friendly and social
Learning difficulties
Short stature
Transient neonatal hypercalcaemia
Supravalvular aortic stenosis
ACYNOTIC

How do you diagnose Williams syndrome?
- Chromosome 7 affects the elastin gene
- Blood test for elastin can tell you about the protein
- Fluorescence in situ hybridization (FISH)
What is the treatment for Williams syndrome?
- Individuals with Williams syndrome should have a formal evaluation by a cardiologist.
- Individuals with elevated blood calcium levels may need to be seen by a nutritionist or followed by a nephrologist.
What are examples of X-linked diseaes?
- Androgen insensitivity syndrome
- Becker muscular dystrophy
- Colour blindness
- Duchenne muscular dystrophy
- E
- F
- G6PD deficiency
- Haemophilia A,B
- Nephrogenic diabetes insipidus
What are examples of autosomal dominant conditions?
- Ehlers-Danlos syndrome
- Familial adenomatous polyposis
- Hereditary haemorrhagic telangiectasia
- Hereditary spherocytosis
- Huntington’s disease
- Marfan’s syndromes
- Myotonic dystrophy
- Neurofibromatosis
- Noonan syndrome
- Osteogenesis imperfecta
- Retinoblastoma
- Tuberous sclerosis
- Von Willebrand’s disease*
What are examples of autosomal recessive conditions?
- Congenital adrenal hyperplasia
- Cystic fibrosis
- Fanconi anaemia
- Friedreich’s ataxia
- Gilbert’s syndrome*
- Haemochromatosis
- Sickle cell anaemia
- Thalassaemias
- Wilson’s disease