Disorders Flashcards
Myotonic Dystrophy
Wasting of the muscles, cataracts, heart conduction defects, endocrine changes, and myotonia.
- Mutation in DMPK gene. DM1 most common
- Triplet Repeat Disorder (CTG repeat) at 3’ end of gene
-Autosomal Dominant
Achondroplasia
FGFR3 (Arg360Gly) mutation results in severe stunting of growth
Codes for transmembrane receptor involved in differentiation of cartilage to bone.
-Autosomal Dominant
Neurofibromatosis
Mutations in neurofibromin(NF1) gene.
Neurofibromin gene codes for a tumor suppressor protein
- Café-au-lait spots
- Neurofibromas: swellings on the skin
- Lisch nodules in the iris of the eye
- Exhibits variable expressivity
- Autosomal Dominant
Hemochromatosis
Excess Iron. Deposits in organs, especially liver, heart and pancreas leading cancer, heart arrhythmias, cirrhosis, etc.
- C282Y mutation of HFE gene most common
- delayed age of onset
-Autosomal Recessive
X-linked recessive disorders
Dystrophin gene: DMD, Becker MD
G6PD deficiency
Hemophilia A & B
Lech-Nyan Syndrome: HGPRT deficiency
X-linked SCID: defect in SCIDX1 gene
(defect in the gamma chain of the receptor for several different interleukins)
Rett Syndrome
Neurodevelopmental, autism spectrum disorder characterized by developmental reversals, especially in the areas of expressive language and hand use.
- X-linked dominant.
- Males with mutant X usually die in utero
Mutation in MeCP2 (methylation/epigenetics)
Incontinentia pigmenti
X-linked dominant
–Males with the disorder die in utero
–Manifests as rashes & blisters in early life
–Later, patches of hyperpigmentation, ‘Marble cake appearance’ of skin
–Mental retardation (in some patients)
–Retinal detachment (in some patients)
Variable expressivity
Huntington Disease
Neurodegenerative disorder, affects muscle coordination leading to cognitive decline and psychiatric problems.
- Triplet repeat expansion (CAG) in coding region of DNA (36-100 repeats)
- Genetic anticipation
- Autosomal Dominant
Familial hypercholesterolemia
High LDL due to LDL receptor deficiency
-Autosomal Dominant
Marfan Syndrome
Connective tissue disorder due to misfolding of fibrillin.
-Autosomal dominant
Osteogenesis imperfecta
‘Brittle bone disease’
Defective connective tissue, deficiency of Type-I collagen.
-COL1A1 and/or COL1A2 gene mutations
- Haploinsufficiency (loss of function of 1 allele)
- Autosomal Dominant
Acute intermittent porphyria
Deficiency of porphobilinogen deaminase in the formation of heme. build up of porphobilinogen and amino-levulinic acid (ALA)
neurologic damage that leads to peripheral and autonomic neuropathies and psychiatric manifestations, and abdomen pain
-Autosomal dominant
Cystic Fibrosis
-Autosomal Recessive
Abnormal transport of chloride and sodium across an epithelium, due to CFTR receptor abnormality
Sickle Cell Anemia
- Autosomal Recessive
- codominance can occure
Characterized by red blood cells that assume an abnormal, rigid, sickle shape. mutation in hemoglobin gene.
Phenylketonuria (PKU)
-Autosomal Recessive
Deficient Phenylalanine hydroxylase or the BH4 coenzyme. Inability to break down phanyalanine to tyrosine.
Intellectual disability. Seizures, delayed development, behavioral problems, and psychiatric disorders.
Mousy odor to urine
Tay-Sach’s disease
-Autosomal Recessive
Hexosaminidase A deficiency. buld up of ganglioside in nerve cells of the brain resulting in premature death. .
cherry-red spot on retina and onion appearance to lysosomes.
Congenital deafness
- Autosomal recessive
- Locus heterogeneity
Homocystinuria
-Autosomal recessive
Cystathionine beta synthase deficiency in the breakdown of methionine resulting in accumulation of homocystine.
Intellectual disability, failure to thrive, seizures, problems with movement, megaloblastic anemia.
-Delayed age of onset
Galactosemia
-Autosomal Recessive
Inability to break down galactose resulting in failure to thrive, seizures, lethargy, liver damage, etc.
Severe Combined Immunodeficiency
- Autosomal Recesive - adenosine deaminase deficiency in purine degradation build up of dATP toxic to B & T cells
- X-linked recessive - SCIDX1 gene mutation leading to mutation in the gamma chain of T cell receptors
Absence of functional T-lymphocytes
Treatment:
Bone marrow transplant
Protein therapy
Gene therapy
Lech-Nyan Syndrome
- X-linked recessive
HGPRT deficiency resulting in neurological manifestations,hyperuricemia, gout, and self mutilation.
Duchenne muscular dystrophy
- X-linked recessive
mutation on the dystrophin gene resulting in muscle wasting and cardiac problems Death before 30.
Becker’s MD a milder form.
Glucose 6 phosphate dehydrogenase(G6PD) deficiency
- X-linked recessive
Hemolytic anemia on ingestion of primaquine, sulfa drugs
Hemophilia A and B
- X-linked recessive
Bleeding disorder resulting in deficient Factor VIII
