Genetics Flashcards
Deep creases in palm and sole + developmental delay + mild dysmorphic features (deep set eyes and an everted lower lip) what mutation?
Mosiac trisomy 8
Features of tetrasomy 12p?
AKA Pallister-Killian Syndrome
Normal blood karyotype.
Coarse facial features and bitemopral sparsity of hair
Severe developmental delay
Karyotype of Klinefelter syndrome
47XXY
Patient with Klinefelter syndrome are at increased risk of what diseases
Pulmonary disease
Varicose veins
Breast cancer, leukaemia and mediastinal germ cell tumors
McCune-Albright syndrome is associated with learning difficulty T/F
F
Note: it is assoc with cafe-au-lait macules, precocious puberty and polyostotic fibrous dysplasia
Features of Cowden syndrome?
Autosomal dominant
Macrocephaly
Variable developmental delay
Increased risk of breast, thryoid and endometrium tumors and skin lesions (including papillomas and facial trichilemmomas)
Mutation associated with cowden syndrome
PTEN gene (AD inheritance)
NSD1 gene or 5q35 deletion, what genetic disoder?
Soto syndomre
Soto syndrome is associated with what abnormalities?
Macrocephaly + large feet and hands + prominent forehead, down slanting palpebral fissues, prominent jaw and high and narrow palate
Seizures
Mild ventricular dilatation
Soto syndrome is mostly due to de novo gene mutations T/F
True
GPC 3 gene mutation, what syndrome?
Simpson-Golab - Behmel syndome
Simpson-Golab-Behmel syndrome is X-linked recessive T/F
True
Note: carrier females can have subtle facial manifestations including a large mouth, pointed chin or coccygeal appendage
What is the most common form of inherited congenital deafness?
Pendred’s syndrome
Note: AR inheritence; presents with simple goitre and mild hypothyroidism; deafness is sensorineural
Clinical features of glutaric aciduria type 1
Choreiform and dystonic movements Normal eye exam Macrocephaly Developmental delay Often presents after a minor illness as the body is working at a higher rate of metabolism which unmasks the deficiency
Canavan’s disease eye findings
Optic atrophy
Alexander disease is associated with hypotonia T/F
F - it is assoc with stiff limbs
Note: rare demyelinating leukodystrophy, presents around 2 yrs old with progressive macrocephaly, seizures, stiff limbs and ataxia
Eye findings in mucopolysaccharidosis?
Corneal clouding (except Hunter syndrome)
Eye findings in GM2 gangliosidosis?
Cherry red spot
Tay–Sachs and Sandhoff disease
What may be seen on a CT brain of a patient with glutaric aciduria type 1?
Subdural effusion
Note: subdural effusion is also a common complication of streptococcal meningitis
Are carnitine levels high or low in carnitine transporter defect?
Very low - as carnitine is not taken up by the cells and hence it is lost in the urine.
Hence diagnosis is confirmed by high fractional excretion of carnitine
Note: also associated with cardiomegaly; carnitine is essential for long chain FA oxidation and FA are the preferred fuel source for the heart
In antenatal screening T21 is a cause of elevated alpha fetoprotein T/F
F - T21 is a cause of REDUCED AFP
Causes of elevated AFP - liver necrosis, anencephaly, spina bifida, sacrococcygeal teratoma
How does arginase deficiency commonly present?
Lab abnormality?
Spastic diplegia and subsequently seizures, ataxia and dystonia
Increased arginine and ammonia
Male with short stature, webbed neck, hypertelorism, downslanting palpebral issues has what syndrome
Noonan syndrome (“male Turner syndrome”)
Other features: skeletal defects, cryptorchidism, bleeding diathesis, card abnormality
What is the most common cardiac abnormality with Noonan syndrome?
Pulmonary stenosis and hypertrophic cardiomyopathy
What is the cardiac abnormality in Turner syndrome
Coarctation of aorta and bicuspid aortic valve
Cardiac abnormality in Alagille syndome
Peripheral pulmonary artery stenosis (up to 90%)
Tetrology of fallot
Cardiac abnormality in William syndrome
Supravalve aortic stenosis
Note: also associated with renal artery stenosis, elfin facies and being overly friendly
What is the most common form of inherted mental retardation affecting boys?
Fragile X syndrome
Female carries of Fragile X syndrome are usually of normal intelligence but may have what?
Premature menopause
What is the gene involved in fragile X
FMR1 gene on x chr; caused by expansion triplet repeats
Mutation in HERG is assoc with what cardiac abnormality
Long QT syndrome
Deletion of 22q11.2 is common in may congenital cardiac diseases including DiGeorge syndrome. What other ones
Tet of Fallot
Common arterial trunk
Familial VSD
Cystinosis causes what acid base abnormality?
Hyperchloraemic acidosis
Also rickets
It is AR
Inheritance of fabry’s disease and broad category of pathology
X linked recessive
Lysosomal storage
Fabry’s disease what cardiac pathology
Mitral valve prolapse
Clinical features of Fabry disease
Neuro: neuropathic pain; decreased ability to sweat; cloudiness of eye, hearing loss
Card: MVP
Derm: dark red spots on the skin called angiokeratomas
Characteristic lab abnormality in MCADD
Hypoketotic hypoglycaemia
Note: this is a fatty acid oxidation defect –> not able to make ketones; mgmt avoid prolonged fasting and glucose supplementation during illness
Other presentations: lethargy, seizure, coma, acute hepatic failure
MECP2 mutation, what disease?
Rett Syndrome
SNRPN mutation, what disease?
Prader Willi
UBE3A mutation, what disease?
Angelman Syndrome
In a pt with pendred syndrome what would you expect to see on imaging of middle/internal ear?
Bilateral dilation of vestibular aquaducts
Inheritance of Marfan’s syndrome
Autosomal dominant
Incidence of PKU
1 in 10,000 live births
Abnormality on chr11p15 is assoc with what syndrome?
Beckwith Wiedemann syndrome
Beckwith Wiedemann is assoc with risk of what malignancy?
Wilms tumor (nephroblastoma) Hepatoblastoma
Note: surveillance
AFP every 2-3 weeks until 4 yrs old + abdo USS every 3 months until age of 8
What is Williams syndrome also known as?
Idiopathic infantile hypercalcaemia
Note: mutation on chr 7
What is the aetiology of Smith-Lemli-Opitz syndrome
Inability to break down cholesterol due to def in cholesterol reductase. This lead to a low cholesterol level, tx is with a high cholesterol diet
Maternal uniparental disomy of chr 15 what syndrome?
Prader Wili
Paternal uniparental disomy of chr 15 what syndrome?
Angelman’s syndrome
Both copys inherited from father
HLA A3 is associated with what disease?
Haemochromotosis
HLA Cw6 is associated with what disease?
Psoriasis
HLA B5 is associated with what disease?
Bechet’s syndrome, polycystic kidney disease, ulcerative colitis
HLA DR2 is associated with what disease?
MS and goodpastures syndrome
HLA DR3 is associated with what disease?
Addison’s disease, Sjogren disease , Graves disease, diabetes mellitus
HLA DR4 is associated with what disease?
Rheumatoid arthritis and diabetes mellitus
Phenylketonuria leads to low phenylalanine serum T/F
F
Due to a def of phenylalanine hydroxylase, hence unable to convert phenylalanine to tyrosine
Patients with phenylketonuria have fair skin T/F
T “dilute pigmentation” due to inadequate melanisation
Other features - low IQ, poor head growth, seizures and eczema-like rash.
MSK abnormalities with Alagille syndrome
Most common: butterfly vertebrae
Less common: Radio-ulnar synostosis and short phalanges
Note: also cholestasis, congenital heart disease (commonly pulmonary valve), anterior segment abnormalities (mainly posterior embryotoxon)
Presentation of ornithine aminotransferase deficiency?
Worsening myopia and night vision
Affects the retina and the choroid
Most males foetuses with incontinentia pigmenti will result in miscarriage. T/F
T
NLG3 is associated with what?
Non syndromic autism
Triple X syndrome is associated with problems of gonadal determination and sexual differentiation T/F
False - this is due to lyonisation/inactivation of the extra X. Hence phenotypically normal.
Note: features are delays in language, gross motor and auditory processing; learning difficulty, EEG abnormalities. Can have premature ovarian failure but normal fertility is usually present
In a pt with Down syndrome and other family members with DS such as first cousins what is the likely cause?
Unbalanced Robertsonian Translocation
Note: this is known as translocation down syndrome, as opposed to T21. A balanced translocation will not result in down syndrome
What is the inheritance of Hunter syndrome?
X linked recessive
Note: most other mucopolysaccharidoses are autosomal recessive
What is the inheritance of hereditary spherocytosis
Autosomal dominant
What is the inheritance of Vit D resistant rickets?
X linked dominant
Galastosaemia can lead to precocious puberty T/F
F - it can lead to delayed puberty in females due to ovaries not producing enough oestrogen