Genetic Disorders Flashcards
Ehler danlos syndrome mutation?
In gene resposible for collagen sytnthesis
Major characters of ehler danlos:
Hyperextensible skin
Hyperflexible and hypermobile joints
Major complication of ehler danlos:
Blidness : retinal dechament or rupture globe
Death from rupture aorta
Bladder rupture and skeletal deformities
Familial hypercholestrolemia
Mutation in:
Gene encoding for receptor protein (LDL receptor)
In familial HCH mutation is impairment of:
LDL transport and catabolism
Leading to++ in LDL amd cholestrol in plasma》atheromas and xanthomas
In familial cholestrolemia
Heterozygous and homozugous:
In hetero 2-3 fold (350mg/dl) stays asymptomatic until adult 》IHD.
In homo 5 fold (600-1200mg/dl) die in 20y from MI.
Neurofibromatosis mutation:
In gene coding for protein regulating cell growth
N.F type 1 other name:
Von recklinghausen disease
N.F type 1 mutation in chromosome :
17
N.F type 1 characters:
Multiple disfiguring n.fibromas (skin carnial n and git).
Dark pigmentation in skin (cafe au lair spots)
Pigmented iris nodule (lisch nodule)
++risk of myeloid leukaemia (200-500 times)
N.f type 2 mutation chromosome:
22
N.f type 2 characters:
Peripheral n.fibroma
Bilateral tumour of the 8 cranial nerve acoustic neuromas) leading to hearing loss
Phenyle ketonuria:
Lack of phenylalanine hydroxylase enzyme L to accumulation of phenylalanine (hyperphenylalaninemia)
C. Features:
Bad odour of urine
Mental retardation 》1/3 unable to walk &1/2 cannot talk
– skin hair pigmentation
Seizures, neurological abnormalities
Phenyl ketonuria treated by:
Restriction of phenylalanine early in life
Tay-sachs D
Lysosomal storage disease
Def in hexosaminidase A (gangliosides)
C.P : mental retadation, neurological dysfunction , death in 2-3 yrs
Nieman-pick d:
LSD, def in sphingomyelinease (sphingomyelin)
C.p : massive visceral enlargement》 V&D, CNS symptoms, death in 1st 3-5 yrs
Gaucher disease:
LSD (the monst common)
Def in glucocerbrosidase (glucosylceramide)
Gaucher d tpyes:
T1 :99% hepatosplenomegally, pancytopenia or thrombocytopenia, absence of CNS involvement, long life
T2: highlt lethal, affect children 3-6 monthes of age witj CNS involvement
T3: intermediate b/w t1 &, t2
Down syndrome
Trisomy 21
Craniofacial feature of Down s
Flat face and occiput
Oblique palpebral fissure, epicanthal fold
Low set ears, protruded tongue
Mental status fo Down s
Mental retardation, their IQs decline progressively with age
Cvs in down s
CHD (ASD, VSD)
Other trisomy variants:
Trisomy 13 patau syndrome
Trisome 18 edward s
Turner’s S
Monosomy 45X0
C. Features of turners s:
Female hypogonadism, failure of breast development
Short stature
Webbed neck, low posterior hair line
Lymphoedema
Co-artation of aorta
Primary amenorrhoea, atrophic streaky ovaries
Broad chest with widely spaced nipples
Klinefilter syndorme
47 XXY
Male with more tham x chromosome
The extra X chromosome origine
In klinefelter s
Could be either maternal or paternal
Half of klinefelter s patient are lost due to:
Spontaneous abortion
C. Features of klinefelter s:
Tall stature with + in length b/w the sole and pubic bone
Atrophiic testis》 hypogonadism
Gynacomastia
Failure of male secondary cgaracters
Minimal or no intellectual impairment
++ risk of type 2 diabetes, breast cancer and autoimmune disease.
Most important method for diagnosis of genetic disorders:
Amniocentesis amd chorionic villi biopsy
Indication of genetic disorders
Maternal age 35y old and over
Previous chromosomal abnormalities
History of familial inborn error of metabolsim
Family hiatory of X-linked disorders.
