Different inheritance patterns Allows for specific patterns of inheritance controlled by a single gene pair (“monogenic”) 4 different types of patterns autosomal dominant autosomal recessive x-linked dominant x-linked recessive additional inheritance effects include imprinting anticipation In general defective structural proteins = AD defective enzymes = AR Pedigree Analysis A pedigree chart displays a family tree and the members of the family affected by a genetic trait Use a pedigree chart can be used to determine the mode of transmission dominance whether the trait is dominant or recessive linkage whether the trait is X-linked or autosomal Key shapes circles represent females squares represent males color a black circle/square represents an individual affected by the genetic trait a white circle/square represents an individual that is not affected by the trait lines horizontal a male and female connected by a horizontal line have mated and have children vertical vertical lines connect parents to their children Autosomal Dominant Description only need to get the abnormal gene from one parent in order for you to inherit the disease. Examples Syndactyly Polydactyly Marfan's syndrome Cleidocranial Dysostosis Hereditary Multiple Exostosis Achondroplasia MED Metaphyseal chondrodysplasia (Schmid and Jansen types) Kniest dysplasia Malignant hyperthermia Ehlers-Danlos syndrome Osteogenesis imperfecta (types I-IV) Osteochondromatosis/Multiple Hereditary Exostosis Osteopetrosis (tarda, mild form) Autosomal Recessive Description an autosomal recessive disorder means two copies of an abnormal gene must be present in order for the disease or trait to develop. Examples Diastrophic Dysplasia Friedreich's Ataxia Gaucher disease Spinal muscular atrophy Sickle cell anemia Hypophosphatasia Osteopetrosis (infantile, malignant form) Sex-linked Recessive (males only) Description X-linked diseases usually occur in males. Males have only one X chromosome. A single recessive gene on that X chromosome will cause the disease. Examples Duchenne muscular dystrophy Becker's muscular dystrophy Hunter's syndrome Hemophilia SED tarda Lesch-Nyhan Sex-linked Dominant Examples Hypophosphatemic rickets Leri-Weill dyschondrosteosis (bilateral Madelung's deformity) Multiple inheritance patterns Examples Charcot-Marie-Tooth (AD, AR, Xlink) Osteopetrosis (AD, AR) Osteogenesis Imperfecta (AR, AD) Neurofibromatosis (AD, AR) SED (AD, Xlink) Miscellaneous Genetic Inheritance Imprinting a genetic phenomenon by which certain genes are expressed in a parent-of-origin-specific manner Examples Angelman Syndrome Prader-Willi Syndrome Anticipation a phenotype occurs earlier (and typically worse) in each subsequent generation common in trinucleotide repeat disorders