Non mendel Genetics

Sex linked inheritance

X linked- genes that are in X chromosome

Y linked- genes that are in Y chromosome

X linked dominance

Male are hemizygote for X linked inheritance

Girls twice affected

Vertical transmission- fathers cannot transmit

Recurrence risk for X linked

Heterozygous female + Homozygous male (normal)

50% of sons and daughters affected

Recurrence risk for X linked

Homozygous female (mutant) + normal male

100% sons and daughters affected

Recurrence risk for X linked

Heterozygous female + hemyzygotic male

50% sons affected

100% daughters affected

Recurrence risk for X linked

Homozygous female (mutant) + hemyzygotic male

100% of both sex affected

Hypophosphatemic rickets

PHEX gene

Xp22.1

Inability to reabsorb phosphate

X linked recessive

Boys are more affected

Only girls are carriers

To exhibit they must be homozygote

Horizontal transmission

Affected fathers cant transmit to sons but carrier for daughters

Recurrence risk for X linked recessive

Carrier mom and affected male

50% normal

50% affected sons and carrier daughters

Recurrence risk for X linked recessive

Unafected mom and affected male

100% normal sons

100% carrier daughters

Recurrence risk for X linked recessive

Carrier mom and unaffected male

50% normal

50% sons affected and carrier girls

Haemophilia

Cant make blood clots

A Haemophilia

B Haemophilia

VIII factor

IX factor

Xq28

Xq27.1

Lyon Hypothesis

One of two X chromosomes is chosen at random for inactivation

X inactivation center contains XIST transcribed ONLY in inactive X chromosome

XIST

X inactive specific transcript

Non coding RNA gene

Xq13

XIST produces RNA that silences X chromosome, marking permanent inactivation

Y linked inheritance

Only boys affected

Only father to son transmission

Mitochondrial Inheritance

Maternal Inheritance

No father transmission

No skip generation

LHON

Missense mutation in mDNA

Leber Hereditary Optic Neuropathy

MT-ND1

MT-ND4

MT-ND4L

MT-ND6