mitochondrial inheritance

inheritance /in·her·i·tance/ (in-her´ĭ-tans)

1. the acquisition of characters or qualities by transmission from parent to offspring.

2. that which is transmitted from parent to offspring.

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cytoplasmic inheritance  mitochondrial i.

dominant inheritance  see under gene.

extrachromosomal inheritance  mitochondrial i.

intermediate inheritance  inheritance in which the phenotype of the heterozygote falls between that of either homozygote.

maternal inheritance  mitochondrial i.

mitochondrial inheritance  the inheritance of traits controlled by genes on the DNA of mitochondria in the ooplasm; thus the genes are inherited entirely from the maternal side, segregate randomly at meiosis or mitosis, and are variably expressed.

recessive inheritance  see under gene.

sex-linked inheritance  see under gene.

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inheritance

The acquisition of traits, characteristics and disorders from parents to their children by transmission of genetic information. Genes come in pairs: one originating from the father, the other from the mother. If an individual presents only the hereditary characteristics determined by one gene of the pair on an autosomal chromosome, that gene is called dominant. Conditions caused by such genes are said to show autosomal dominant inheritance. For instance, for a rare autosomal dominant disease, if one parent is affected, then on average about 50% of their children will also be affected, irrespective of the children's sex. Examples: Marfan's syndrome, congenital stationary night blindness, neurofibromatosis 1 and 2, von Hippel-Lindau disease. If the individual does not present the hereditary characteristics unless both genes in a pair are of the same type, then the gene is called recessive. Conditions caused by such genes are said to show autosomal recessive inheritance. For a rare autosomal recessive disease, if a child is affected, then on average about 25% of their siblings will also be affected, irrespective of their sex. Examples: Laurence-Moon-Biedl syndrome, Tay-Sachs disease, oculocutaneous albinism, galactokinase deficiency.Thirdly, inheritance may be controlled by genes on one of the sex chromosomes, most often the X chromosome. A recessive mutation on the single X chromosome carried by a male will cause a disease, whereas in the female, a recessive X chromosome mutation would have to be carried on both of her X chromosomes. Therefore in X-linked recessive inheritance (sex-linked recessive inheritance) males are affected more often than females. Examples: colour blindness, ocular albinism, choroideremia. A fourth type of inheritance considered in ophthalmic practice is mitochondrial (maternal) inheritance in which the inheritance of a trait encoded in the mitochondrial DNA is transmitted through the female line (mother to son or mother to daughter). Examples: Leber's hereditary optic atrophy; Kearns-Sayre syndrome. See acquired; chromosome; defective colour vision; gene; hereditary.

Table I5 Divisions of the infrared spectrum
IR-A (near)	780-1400 nm
IR-B (middle)	1400-3000 nm
IR-C (far)	3000-1 000 000 nm

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mitochondrial inheritance

 The inheritance of a trait encoded in the mitochondrial genome, always of maternal origin