genetic + immunodeficiency disorders Flashcards
1
Q
Fragile X syndrome
A
- triplet repeat CGG
- FMR-1 gene (Familial mental retardation) on X chromo
- elongated face with large jaw, large everted ears, macroochidism
Fragile X = eXtra large testes, jaw, ears
2
Q
Edwards Syndrome
A
- trisomy 18 (Election = age 18)
- meiotic non disjunction; increased maternal age has higher risk
- severe intellectual disability, rocker-bottom feet, micrognathia (small jaw), low set ears, congenital heart disease
- death w/i 1 year
- quad screen at birth: low AFP, low BHCG, low estriol, low/normal inhibin A
3
Q
Patau syndrome
A
- trisomy 13 (puberty = 13)
- meiotic nondisjunction, increased risk with higher maternal age
- cleft Palate/lip, holoProsencephaly, Polydactyly
- severe mental retardation, microcephaly, rocker-bottom feet, congenital heart disease (like Edwards)
4
Q
Cri du chat syndrome
A
- chromosomal deletion (chromosome 5)
- high-pitched cat-like cry/mewing, mental retardation, congenital heart disease, microcephaly
5
Q
DiGeorge Syndrome
A
- developmental failure of 3rd and 4th pharyngeal puches (due to chromosomal microdeletion)
- T-cell defiency (no thymus)
- hypocalcemia (no parathyroids)
- abnormalities of heart, great vessels and face
6
Q
Severe Combined Immunodeficiency (SCID)
A
- defective cell-mediated (T cell) and humoral immunity (B cell)
- “bubble baby” – sterile isolation
- etiology: cytokine receptor defects, adenosine deaminase deficiency, MHC Class II deficiency
- susceptibility to fungal, viral, bacterial, protozoal infectoins and live vaccines
7
Q
X-linked Agammaglobulinemia
A
- mutated Bruton tyrosine kinase; X-linked
- disordered B cell maturation –> complete lack of Ig
- presents after 1st 6 mo (maternal Abs protective til then)
*think B for Bruton Tyr kinase, B-cells
8
Q
hyper-IgM syndrome
A
- mutated CD40L (on helper T cell) or CD40 receptor (on B cells) –> 2nd signal can’t be delivered to helper T cells during B-cell activation
- can’t class switch –> elevated IgM
9
Q
Chronic Granulomatous Disease
A
- NADPH oxidate defect –> poor O2-dependent killing of microbes
- no oxidative burst in phagolysosomes of neutrophils (O2 –> superoxide radical)
- recurrent infection and granuloma formation with catalase positive organisms (S. aureus, Pseudomonas cepacia, Serratia)
- screen via nitroblue tetrazolium test (dye turns blue if NADPH oxidase can convert O2 to superoxide)
10
Q
Phenylketonuria
A
- deficiency of phenylalanine hydroxylase –> toxic levels of phenylalanine (normally converted to Tyr)
- mental retardation
- light colored skin (lack of Tyr = lack of melanin)
- mousy odor of sweat and urine
disorder of aromatic aa metaboism = musty BO
11
Q
Alkaptonuria (onchronosis)
A
- deficiency of homogentisic oxidase (necessary for degradation of Tyr)
- accumulation of homogentisic acid (affinity for CT –> black upon oxidation)
- dark CT + cartilage (nose and ears), black urine (upon exposure to air)
- early onset degenerative arthritis
12
Q
Maple Syrup Urine Disease
A
- blocked degradation of branched aa (Isoleucine, Leucine, Valine) due to decreased alpha-ketoacid dehydrogenase
- increased alpha-ketoacids in blood
- AR
- CNS defects, intellectual disability, death
- urine smells like maple syrup/burnt sugar
branched aa = maple syrup tree
13
Q
Von Gierke disease
A
- type I glycogen storage disease
- glucose-6-phosphatase deficiency –> can’t convert glycogen into free glucose
- fasting hypoglycemia, increased glycogen storage in liver (hepatomegaly)
- AR
- tx: frequent oral glucose
14
Q
Pompe disease
A
- type II glycogen storage disease
- lysosomal alpha-1,4-glucosidase (acid maltase)
- cardiomyopathy, hepatomegaly, skeletal muscle hypotonia –> early death
- Pompe trashes the Pumps (heart, liver, muscle)
- Cori disease = milder form (debranching enzyme alpha-1,6-glucosidase)
15
Q
McArdle Disease
A
- type V glycogen storage disease
- muscle glycogen phosphorylase deficiency
- increased glycogen in muscle but can’t break it down –> exercise-induced muscle cramps and myoglobinuria
- AR
- McKardle = Muscle
