π¨βπ©βπ§βπ¦ Genetics D/O Flashcards
Trisomy 21
DOWN SYNDROME
Most common chromosomal disorder and cause of congenital mental retardation
DOWN SYNDROME
95% due to MEIOTIC NONDISJUNCTION of homologous chromosomes
DOWN SYNDROME
Advanced maternal age (>45.y.o.) (35-40)
DOWN SYNDROME
Most common preventable congenital mental retardation
CREETINISM
Mongoloid facies features (flat faced, low bridged nose and epicanthal folds)
DOWN SYNDROME
Brushfield spots-speckled appearance of the iris
Muscular hypotonia
DOWN SYNDROME
Simian crease or palmar crease
DOWN SYNDROME
Alzheimerβs disease in >35 years old (in adults)
DOWN SYNDROME
Most common malformation of DOWN SYNDROME
ENDOCARDIAL CUSHION DEFECT
Increase risk of ACUTE LYMPHOBLASTIC LEUKEMIA (in children)
DOWN SYNDROME
Most common ASD in DOWN SYNDROME in adults
Ostium primum
Most common ASD in DOWN SYNDROME IN CHILDREN
Ostium secundum
Antenatal
AFP value of approximately 0.7 MoM
HCG level of approximately 2.0 MoM
Unconjugated estriol concentration of approximately 0.8 MoM
TRIPLE TEST
A fourth marker, dimeric inhibin alpha was added values of about 1.8 MoM are reported in DOWN SYNDROME
QUAD TEST
Neurofibrillary tangle (NFT)
Amyloid plaques
- both composed of protein TAU
Alzheimers Disease
Trisomy 18
EDWARDS SYNDROME
Severe MR
Rocker bottome feet
Low set ears
Micrognathia
CHD
Clenched hands (flexion of fingers) Overlapping flexed fingers
Prominent occiput
Death within 1 year
EDWARDS SYNDROME
47XX or XY+18
EDWARDS SYNDROME
Second most common autosomal trisomy after trisomy 21
EDWARDS SYNDROME
Trisomy 13
PATAU SYNDROME
47XX or XY+13
PATAU SYNDROME
Trisomy 13
PATAU SYNDROME
MULTIPLE CONGENITAL ANOMALIES
Severe MR
Microphthalmia
Microcephaly
Cleft palate/lip
Polydactyly
Congenital heart disease
Death occurs within 1 year of birth
PATAU SYNDROME
Taken with misoprostol
PATAU SYNDROME
Cholesterol transport across liver cell impaired
FAMILIAL HYPERCHOLESTEROLEMIA
HDL receptor defect
TANGIERS DISEASE
47XX or XY+21
DOWN SYDNROME
LDL receptor defect
FAMILIAL HYPERCHOLESTEROLEMIA
Deficiency of a-galactosidase A
FABRYβs DISEASE
Deficiency of b-glucocerebrosidase
GAUCHERS DISEASE
Deficiency of sphingomyelinase
NIEMANN-PICK DISEASE
Absent HEXOSAMINIDASE A deficiency
TAY-SACHβ S DISEASE
Deficiency of alpha-L iduronidase
HURLERβs DISEASE
Deficiency of iduronate-2-sulfatase
HUNTERβs DISEASE
Erlemeyer flask appearance
GAUCHERS DISEASE
Crumpled paper or tissue appearance
GAUCHERS DISEASE
Deficiency of HEXOSAMINIDASE A and B
SANDHOFF DISEASE
Fibrillin-1 defect
MARFAN SYNDROME
D/O causing ICTOPIA LENTIS
MARFAN SYNDROME and HOMOCYSTINURIA
Sublaxation of lenses
ICTOPIA LENSES
Classical hypermobility
EHLERS DANLOS SYNDROME
Defective collagen (type 1,3 and 5)
EHLERS DANLOS SYNDROME
What collagen is OSTEOGENESIS IMPERFECTA
Type 1
Skeletal features:
- most striking feature
- unusually tall with long, thin extremities (dolichostenomelia)
- long tapering fingers and toes with spider-like appearance (arachnodactyly)
MARFANS SYNDROME
Cardiovascular features:
- most life threatening feature
- 2 common lesions: mitral valve prolapse, dilation of the ascending medionecrosis
MARFANS SYNDROME
First one to be described HOMOGENTISIC ACID
ALCAPTONURIA
HOMOGENTISIC ACID OXIDASE deficiency
ALCAPTONURIA
Pigmentation of sclera
OSLERS SIGN
Note: OSLERβS NODE - Infective Endocarditis
Black urine
Black nails (OCHRONOSIS)
Black skin
Black joint cartilage (severe arthritis)
ALCAPTONURIA
Happy puppet syndrome
ANGELMAN SYNDROME
Chromosome 15
ANGELMAN SYNDROME and PRADER-WILLI SYNDROME
Chromosome 17
VON RECKLINGHAUSEN
Obesity, small stature, hyperphagia and mental retardation
Deletion of chromosome 15
PRADER WILLI SYNDROME
Hereditary motor and sensory neuropathy (HMSN)
CHARCOT MARIE TOOTH DISEASE
Peroneal muscular atrophy (PMA)
CHARCOT MARIE TOOTH DISEASE
Most common peripheral neuropathy worldwide
CHARCOT MARIE TOOTH DISEASE
70-80% is the duplication of a large regiom on the short arm of chromosome 17 that includes the gene PMP22
CHARCOT MARIE TOOTH DISEASE
Foot drop
High arched foot
Stork legs
Hammer toes
CHARCOT MARIE TOOTH DISEASE
Ataxia, nystagmus, kyphoscoliosis and pes cavus
Chromosome 9
FRIEDREICH ATAXIA