Genetics Block 3 Diseases

Front 1

Downs

Back 1

- Autosomal Trisomy
- 95% extra Chromosome 21
- 4% robertsonian translocation between 21q and long arms of 14 or 22
- MR, flat nasal bridge, epicanthanl folds (slanted palpebral fissures), protruding tongue, simian crease, clinodactyly of 5th digit (curving towards 4th), congenital heart defects

Front 2

Edwards

Back 2

- Autosomal Trisomy of 13
- MR
- "rocker bottom feet"
- low-set ears, micrognathia,
hypoplastic (underdeveloped ) fingers, absent thumbs,
cryptorchidism in males, ventricular septal defects, legs are crossed

Front 3

Patau

Back 3

- Autosomal Trisomy
- Chromosome 18 (80% trisomy, the rest Robertsonian)
-Mental retardation, microphthalmia, cleft lip and palate, poly­dactyly,
rocker-bottom feet, congenital heart disease.
Similar to and more severe than Edward’s Syndrome. Death by age one.

Front 4

Cri-du-Chat

Back 4

- Autosomal Deletion
- long deletion of short arm of chromosome 5
- crying infants sound like mewing cats, microcephaly, hypertelorism (widely spaced eyes),
epicanthal folds, low set ears, micrognathia, severe mental retardation, and heart defects

Front 5

X-linked Ichthyosis

Back 5

- microdeletion
- complete or partial deletion of STS gene on X chromosome
- steroid sulfatase
- see in males
- drying and scaling of skin in neck, upper trunk and scalp
- "dirty face"
- corneal opacities

Front 6

Klinefelters

Back 6

- Sex chromosome aneuploidy
- Non-disjunction of sex chromosome during Meiosis 1 of either parent or mother in Meiosis 2
-XXY
-males
- Hypogonadism, tall stature, gynecomastia.
- mild MR
- diagnostic at puberty, only one Barr body on buccal smear

Front 7

Trisomy X

Back 7

- Sex chromosome aneuploidy
- non-disjunction during meiosis 2 of mom or dad
- 1/1000 female births
- super female

Front 8

Williams

Back 8

- AD
- Contiguous microdeletion on chromosome 7q11.23
- elastin and LIM kinase genes are deleted
- elastin --> vascular dx
- LIM Kinase--> visuospatial constructive cognition
- “Elfin-like” facial features, heart and blood vessel problems, irritability during infancy, dental and kidney abnormalities, hyperacusis, musculoskeletal problems. ** Individuals with Williams’s syndrome have remarkable musical & verbal abilities. Also tend to be very sociable.

Front 9

Campomelic Dysplasia

Back 9

- AD, sex reversal in males w/o H-Y Ag
- SOX9
- Sex determining region of Y (SRYi7) related gene
- Anterior bowing of the long bones, particularly of femur and tibia with severe angulations, growth restriction, bell-shaped narrow chest, eleven pair of ribs, cleft of the soft palate, hypertelorism, low-set and malformed ears, hydrocephalus, and ambiguous genitalia

Front 10

XYY Syndrome

Back 10

- Sex Chromosome
- Males
- Nondisjunction in Meiosis II --> atypical YY sperm
- XYY-47,XY
- Tall, learning difficulties, delayed speech & language skills

Front 11

Turners

Back 11

- Sex Chromosome
- 45,XO
- nondisjunction in meiosis that leads to a lack of sex chromosome in either parents gametes

- Short stature, lymphoedema of hands & feet, broad chest, wide nipples, low hairline, low set ears, reproductive sterility, amenorrhea, increased obesity

Front 12

Spino Bulbar
Muscular
Dystrophy
(Kennedy's)

Back 12

- X-Linked Recessive Male, Caucasian and Asian
- On chromosome Xq11-q12
- CAG repeat expansion in exon 1 of the AR gene
- Androgen Receptor affected
- Androgen receptor is a member of the steroid superfamily
- Normally encodes for a 919
Amino acid protein
- Gradual progressive neuromuscular disorder.
- Affects the MN which results in proximal muscle weakness, muscle atrophy
- Patients will show gynecomastia, testicular atrophy and reduced fertility