PEDIGREE CONSTRUCTION AND HUMAN TRAITS

7 Jan 1996, 10 Jan 01, 11 Jan 02, 12 Jan 04, 10 Jan 05, 14Jan08

GMSLG 7^th: : pp. 41-52 (Tab 2-16, p 41), Klug and Cummings, 4^th: p 69, Tamarin 4^th p 82-87, GWLC, 9th: p 66-75

7 Jan 1996, 10 Jan 01, 11 Jan 02, 12 Jan 04,

Pedigrees can be used to determine mode of inheritance even with small number of progeny.

Family tree, indicates phenotype of each family member

CONVENTIONS: (see p 66)

                       female                       circles

                       male                          squares

                       unknown                   diamond

                       parents                      connected by horizontal line

                       siblings                     vertical line above connects to parental bond, horizontal to other siblings

                       dizygotic                   connected by diagonal lines directly to sibship line

                       monozygotic             connected by diagonal lines to parental, single horizontal to each other

                       affected                     shaded square or circle

                       heterozygotes            (they have dominant phenotype) half shaded

                       arrow                        indicates propositus (proposita) first individual which drew attention

                       roman numerals        Generations are indicated by I, II, III, IV, etc

                       arabic numerals         number individuals within generation, arranged chronologically: 1, 2, 3, etc.

consanguineous marriage is one between relatives (incestuous if against law)

INDICATORS OF TYPES OF INHERITANCE (* MARKS BEST INDICATOR):

       Autosomal Recessive:      *   if both parents affected, all children affected

       (p 67)                                       often skips generations

equal distribution between sexes

often in consanguineous marriages

when one parent and a child is affected ½ of children are affected

Most affected individuals have normal parents

       Autosomal Dominant      *   does not skip generation (except with poor penetrance)

       (p 69)                                       affected person x normal yields ½ affected children

distribution between sexes equal

       Sex-linked recessive         *   mothers of affected males usually known to have male relatives affected

       (p 71)                                 *   sons of affected mothers all affected

most affected persons are male

affected females all have affected fathers, mothers at least carriers

½ sons of carrier mothers affected

       Sex-linked dominant        *   affected males all have affected mothers

       (p 73)                                 *   all females affected of affected father, not sons

does not skip generations

½ children of affected mother affected

affected females come from either father or mother

HUMAN TRAITS (alphabetically) (GMSLG 7^th p 426, Klug and Cummings, 4^th: p 69, Tamarin 4^th : p 82-87):

RECESSIVE

albinism

alkaptonuria

atasia telangiectasia

color blindness

cystic fibrosis

Duchenne muscular dystrophy

galactosemia

hemophilia

Lesch-Nyhan syndrome

phenylketonuria

sickle-cell anemia

Tay-Sachs disease

DOMINANT

achondroplasia

brachydactyly

Brown eyes

Congenital stationary night blindness

Detached earlobe

Ehler-Danlos syndrome

Fascio-scapulo-humeral muscular dystrophy

Huntington disease

Hypercholesterolemia

Marfan Syndrome

Middigital hair 

Neurofibromatosis

Phenylthiocarbamide tasting (PTC)

Tongue roller

Widow's peak