Friday, February 18, 2011

Genetic diseases

MUTATIONS

Mutations involving nucleotides

Point mutation

Silent
Misesnse
Nonsense

Frame shift mutation – deletions and insertions

Trinucleotide repeat sequence





Mendelian disorders

Autosomal dominant diseases

Nervous

Huntington disease
Neurofibromatosis
Myotonic dystrophy
Tuberous sclerosis

Urinary

Polycystic kidney disease

Gastrointestinal

Familial polyposis coli


Hematopoietic

Hereditary spherocytosis
von Willebrand disease

Skeletal

Marfan syndrome
Ehlers-Danlos syndrome (some variants)
Osteogenesis imperfecta
Achondroplasia

Metabolic

Familial hypercholesterolemia
Acute intermittent porphyria


Autosomal Recessive Disorders

Metabolic

Cystic fibrosis
Phenylketonuria
Galactosemia
Homocystinuria
Lysosomal storage diseases
a1 -Antitrypsin deficienc
Wilson disease
Hemochromatosis
Glycogen storage diseases

Hematopoietic

Sickle cell anemia
Thalassemias

Endocrine
Congenital adrenal hyperplasia

Skeletal

Ehlers-Danlos syndrome (some variants)
Alkaptonuria

Nervous

Neurogenic muscular atrophies
Friedreich ataxia
Spinal muscular atrophy




X-Linked Recessive Disorders

Musculoskeletal
Duchenne muscular dystrophy

Blood
Hemophilia A and B

Chronic granulomatous disease

Glucose-6-phosphate dehydrogenase deficiency

Immune Agammaglobulinemia

Wiskott-Aldrich syndrome

Metabolic

Diabetes insipidus
Lesch-Nyhan syndrome

Nervous

Fragile-X syndrome


Biochemical and Molecular Basis of Some Mendelian Disorders

Enzyme Phenylalanine hydroxylase mutation: reduced amount of enzyme causing Phenylketonuria

Hexosaminidase mutation with stop codon:
reduced amount causing Tay-Sachs disease

Adenosine deaminase mutation causing Severe combined immunodeficiency

a1 –Antitrypsin mutations: impaired secretion from liver to serum, causing emphysema and liver cirrhosis

Low-density lipoprotein receptor mutations: Familial hypercholesterolemia

Vitamin D receptor mutations: Vitamin D-resistant rickets

Hemoglobin gene Deletions: reduced amount causing Thalassemia

Hb Point mutations: abnormal structure causing Sickle cell anemia

Cystic fibrosis transmembrane conductance regulator( CFTR) mutation causingCystic fibrosis

Collagen gene mutations cause reduced amount causing Osteogenesis imperfecta; Ehlers-Danlos syndromes, etc

Fibrillin mutation causing Marfan syndrome

Dystrophin Deletion with reduced synthesis:
Duchenne/Becker muscular dystrophy

Spectrin, ankyrin of RBC mutation: Hereditary spherocytosis

Factor VIII Deletions, insertion or nonsense mutations: reduced synthesis or abnormal factor VIII causing Hemophilia A

Rb protein Deletions causing Hereditary retinoblastoma

Neurofibromin gene mutation causing Neurofibromatosis type 1


Schematic diagram illustrating the pathogenesis of lysosomal storage diseases. In the example shown, a complex substrate is normally degraded by a series of lysosomal enzymes (A, B, and C) into soluble end products. If there is a deficiency or malfunction of one of the enzymes (e.g., B), catabolism is incomplete and insoluble intermediates accumulate in the lysosomes.

Some storage disesases

Lysosomal storage diseases

Gaucher’s disease
Niemann Pick Disease
Gangliosidosis
Sphingolipidosis
Tay Sachs disease
Sandhoff’s disease
Fabry’s disease

Glycogen storage diseases

Von Gierke’s disease
McArdle’s disease
Pompe’s disease


Pathways of glycogen metabolism. Asterisks mark the enzyme deficiencies associated with glycogen storage diseases







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