Disorders (2) Flashcards
(39 cards)
What is the molecular cause of fragile X?
CGG repeat expansion in FMR1 gene leading to methylation of the gene
What is the breakdown of repeat numbers in fragile X syndrome?
- intermediate = 45-54
- premutation = 55-200
- full mutation = >200
Name 9 features of fragile X syndrome
- DD
- MR
- autistic features
- hand flapping
- prominent jaw
- prominent forehead
- big ears
- long face
- machroorchidism
What percentage of people with fragile X syndrome have a repeat expansion
> 99%
Does anticipation occur in fragile X syndrome?
yes, with maternal transmission
Order the following from most to least heritable: schizophrenia, major depressive disorder, bipolar disorder,
- bipolar: up to 93%
- schizophrenia: up to 90%
- major depressive: up to 42%
Are most triplet repeat expansions located in the coding or noncoding regions?
noncoding;
exceptions: HD, SCA
What is the inheritance pattern of Friedrich’s ataxia?
AR
What triplet repeat causes Friedrich’s ataxia and where in the gene is it located?
GAA repeat
noncoding region
When does Friedrich’s ataxia typically onset?
between 1 and 15 years
Does expansion occur in Friedrich’s ataxia?
Anticipation?
expansion through maternal transmission,
no anticipation
What percentage of ALS is familial?
10%
What is the average age on onset of familial ALS?
46 y
What percentage of ALS patients develop FTD?
20%
Name 6 main features of Rett syndrome
- regression of language
- regression of motor skills
- hand movements
- seizures
- acquired microcephaly
- prolonged QT
What are the subtypes and corresponding inheritance patterns for LGMD?
LGMD1: AD inheritance
LGMD2: AR inheritance
What is the natural history of Meckel-Gruber syndrome?
neonatal lethal
What 7 things should be ruled out when considering an Alzheimer’s diagnosis?
- thyroid disease
- vitamin deficiency
- brain tumor
- drug intoxication
- chronic infection
- depression
- stroke
What percentage of achondroplasia cases are de novo?
80%
What is the protein substitution that causes nearly all cases of achondroplasia?
Gly380Arg
What are drusen?
small deposits in the eye which are the hallmark feature on exam for age-related macular degeneration
What type of vision does age-related macular degeneration affect?
central
What is the inheritance pattern of CHARGE syndrome?
AD
What are the main features of CHARGE syndrome?
Coloboma Heart defects Atresia of the choanae Retardation of growth and development Genital abnormalities Ear anomalies
