Pedigrees

Pedigree Chart

A diagram showing the genetic relationships and traits across generations.

Generation

A step in line of descent, written using Roman numerals (e.g., I, II, III).

Unaffected male

Shown as an unshaded/empty square .

Unaffected female

Shown as an unshaded/empty circle .

Affected male

Shown as a fully shaded/filled square .

Affected female

Shown as a fully shaded/filled circle .

Consanguineous Breeding

Breeding between close genetic relatives (indicated by a double line).

Autosomal Dominant

Pattern: Appears in every generation; affected parents can have unaffected kids.

Autosomal Recessive

Pattern: Can skip generations; unaffected parents can have affected kids.

X-Linked Dominant

Pattern: Affected fathers pass it to all of their daughters, but none of their sons.

X-Linked Recessive

Pattern: Affects males way more often; skips generations through carrier mothers.

Y-Linked

Pattern: Passes strictly from fathers to all sons; females never have it.