X linked and mitochondrial inheritance Flashcards
X chromosome inactivation occurs when?
1st week of embryogenesis
Nonrandom vs skewed x chromosome inactivation
Nonrandom- when structurally abnormal x chromosome present, more of normal xs are turned on usually
Skewed- observed when female shows signs of x linked recessive condition
X linked dominant conditions (4)
Hypophosphatemic Rickets
Fragile X syndrome
Charcot Marie Tooth
Rett Syndrome
Clinical manifestation of hypophosphatemic rickets (3)
Hypophosphatemia
short stature
bone deformity
Mutation leading to hypophosphatemic rickets occurs on the ____ gene which regulates _____. This inhibits ______
Gene: PHEX
Regulates fibroblast growth factor
Inhibits the kidneys ability to reabsorb phosphate into the blood stream
Fragile X syndrome gene
FMR1
Fragile X syndrome exhibits ______ and ________.
Anticipation
Maternal transmission bias
Clinical manifestations of Fragile X (6)
intellectual disabilities large ears, long face, macroorchidism autistic behavior social anxiety hand flapping/biting agression
Other conditions associated with FMR1
Fragile X Associated Tremor Ataxia (FXTAS)
FMR1- related primary ovarian insufficiency
CGG repeats fragile X: grey zone, premutation, and full mutation
46-65: Grey
56-200: Premutation
>200: Full mutation
Mutation rate of Rett syndrome
95%
Clinical Manifestations of Rett syndrome (6)
Loss of normal movement and coordination Acquired microcephaly Loss of communication skills Failure to thrive Seizures Abnormal hand movements
Rett syndrome gene mutation
MECP2
MECP2 gene (Rett) encodes for what protein?
Methyl CpG binding protein
Essential for the normal function of nerve cells
X-linked Recessive Disorders (4)
Lesch-Nyhan Syndrome
Hemophilia A
Fabry’s disease
Dystrophonpathies