Medical genetics and congenital disorders Flashcards
Name clinical features of trisomy 21
Hypotonia Mental retardation Brachycephaly Flat facial profile Upslanting eyes Epicanthic folds Flat nasal bridge Small, low-set ears Protruding tongue Short stature Brachydactyly 5th finger clinodactyly Single palmar crease Sandal gap Congenital heart defect Duodenal atresia
How can you diagnose trisomy 21?
QF-PCR aneuploidy test
Karyotyping
What is the cause of oculocutaneous albinism type II?
Mutation in P gene on chromosome 15 -> AR single gene disorder
Name the clinical features of OCA2
Depigmented hair, skin and eyes
Nystagmus
Reduced visual acuity
What should you screen OCA2 patients for?
Visual problems
Skin cancer
Name examples of AD inheritance
Achondroplasia
NF type I
Marfan’s syndrome
Huntington’s disease
Name examples of AR inheritance
Oculocutaneous albinism SMA Sickle cell disease Thalassemia Cystic fibrosis IEM
Name examples of XLR inheritance
DMD
Haemophilia A
Haemophilia B
Fragile X syndrome
What is the triplet repeat and normal repeat size in Huntington’s disease?
CAG
9-30
What is the triplet repeat and normal repeat size in Friedrich’s ataxia?
GAA
8-33
What is the triplet repeat and normal repeat size in Fragile X syndrome?
CGG
10-50
Name examples of imprinting disorders
Prader-Willi syndrome
Angelman syndrome
Beckwith-Wiedemann syndrome
How is mtDNA inherited?
Exclusively maternally inherited
What can cause fetal akinesia sequence?
Fetal constraint
Single gene disorder (congenital MD)
Name clinical features of neural tube defects
Anencephaly
Spina bifido
Encephalocoele
What are complications of neural tube defects?
Death Leg paralysis Bladder/bowel incontinence Hydrocephalus Developmental delay
Name clinical features of FAS
Growth retardation Short palpebral fissues Flat midface Underdeveloped philtrum Thin upper lip Neurodevelopmental delay Assoc congenital disorders
What is deformation?
External force changes the shape of the normal tissues of the developing fetus
What is disruption?
External agent destroys the normal tissues of a part of the developing fetus
What is dysplasia?
Abnormal development of a single tissue type
What is malformation?
Abnormal embyronic development
What are the 5 questions a clinical faced with an individual with a birth defect/complex disorder should answer?
What is it? What caused it? What does it mean for the affected person? Will it happen again? Can it be prevented?
What should non-blood samples for single gene testing always be submitted in?
Saline NOT formalin
