Pedigree chart
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A pedigree chart is a diagram that shows the occurrence and appearance of
phenotype right , Here the relation between genotype and phenotype is illustrated, using a Punnett square, for the character of petal color in pea plants. The letters B and b represent genes for color, and the pictures show the resultant phenotypes. Thi ...

phenotype
s of a particular gene or
organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy (biology), taxonomy into groups such as Multice ...

organism
and its
ancestor An ancestor, also known as a forefather, fore-elder or a forebear, is a parent A parent is a caregiver of the offspring In biology, offspring are the young born of living organism, organisms, produced either by a single organism or, in the ...

ancestor
s from one generation to the next, most commonly
humans Humans (''Homo sapiens'') are the most populous and widespread species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species ...
, show
dog The domestic dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated form of wolf. The dog descended from an ancient, extinct wolf, with the modern grey wolf being the dog's nearest living relative. The dog was the first ...

dog
s, and race
horse The horse (''Equus ferus caballus'') is a Domestication, domesticated odd-toed ungulate, one-toed ungulate, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two Extant taxon, extant subspecies of wild horse, ''Equus ferus' ...

horse
s.


Definition

The word pedigree is a corruption of the Anglo-Norman French ''pé de grue'' or "crane's foot", either because the typical lines and split lines (each split leading to different offspring of the one parent line) resemble the thin leg and foot of a crane or because such a mark was used to denote succession in pedigree charts. A pedigree results in the presentation of family information in the form of an easily readable chart. It can be simply called as a "family tree". Pedigrees use a standardized set of symbols, squares represent males and circles represent females. Pedigree construction is a family history, and details about an earlier generation may be uncertain as memories fade. If the sex of the person is unknown a diamond is used. Someone with the phenotype in question is represented by a filled-in (darker) symbol. Heterozygotes, when identifiable, are indicated by a shade dot inside a symbol or a half-filled symbol. Relationships in a pedigree are shown as a series of lines. Parents are connected by a horizontal line and a vertical line leads to their offspring. The offspring are connected by a horizontal sibship line and listed in birth order from left to right. If the offspring are twins then they will be connected by a triangle. If an offspring dies then its symbol will be crossed by a line. If the offspring is still born or aborted it is represented by a small triangle. Each generation is identified by a
Roman numeral Roman numerals are a numeral system A numeral system (or system of numeration) is a writing system A writing system is a method of visually representing verbal communication Communication (from Latin ''communicare'', meaning "to s ...
(I, II, III, and so on), and each individual within the same generation is identified by an
Arabic numeral Arabic numerals are the ten digits: 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9. The term often implies a decimal The decimal numeral system A numeral system (or system of numeration) is a writing system ...

Arabic numeral
(1, 2, 3, and so on). Analysis of the pedigree using the principles of
Mendelian inheritance Mendelian inheritance is a type of biological Biology is the natural science Natural science is a branch of science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific me ...

Mendelian inheritance
can determine whether a trait has a dominant or recessive pattern of inheritance. Pedigrees are often constructed after a family member afflicted with a genetic disorder has been identified. This individual, known as the
probandIn medical genetics Medical genetics is the branch of medicine that involves the diagnosis and management of hereditary disorders. Medical genetics differs from human genetics in that human genetics is a field of scientific research that may or m ...
, is indicated on the pedigree by an arrow. These changes may occur yearly or monthly. File:Wiki Drawing - Y-Linked (1).svg, In a Y-linked disorder, only males can be affected. If the father is affected all sons will be affected. It also does not skip a generation. File:Wiki Drawing - Mitochondrial.svg, In mitochondrial disorders it is only passed on if the mother is affected. If the mother is affected, all offspring will be affected. If the father is affected, he does not pass it on to his offspring. File:Wiki Drawing - Autosomal Recessive (2).svg, In an autosomal recessive disorder, both parents can not express the trait, however, if both are carriers, their offspring can express the trait. Autosomal recessive disorders typically skip a generation, so affected offspring typically have unaffected parents. With an autosomal recessive disorder, both males and females are equally likely to be affected. File:Wiki Drawing - Autosomal Dominant (1).svg, Autosomal dominant disorders do not skip a generation, so affected offspring have affected parents. One parent must have the disorder for its offspring to be affected. Both males and females are equally likely to be affected, so it is an autosomal disorder. File:Wiki Drawing - X-Linked Recessive (1).svg, In a X-linked recessive disorder, males are more likely to be affected than females. Affected sons typically have unaffected mothers. The father also must be affected for daughter to be affected and the mother must be affected or a carrier for the daughter to be affected. The disorder is also never passed from father to son. Only females can be carriers for the disorders. X-linked recessive disorders also typically skip a generation. File:Wiki Drawing - X-Linked Dominant (1).svg, In a X-Linked dominant disorder, if the father is affected all daughters will be affected and no sons will be affected. It does not skip a generation and if the mother is affected she has a 50% chance of passing it onto her offspring.


In human use

In
England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest of England and the Celtic Sea to the southwest. En ...

England
and
Wales Wales ( cy, Cymru ) is a country that is Countries of the United Kingdom, part of the United Kingdom. It is bordered by England to the Wales–England border, east, the Irish Sea to the north and west, and the Bristol Channel to the south. It ...

Wales
pedigrees are officially recorded in the
College of Arms The College of Arms, or Heralds' College, is a royal corporation A corporation is an organization—usually a group of people or a company—authorized by the state to act as a single entity (a legal entity recognized by private and publi ...
, which has records going back to the Middle Ages, including pedigrees collected during roving inquiries by its
herald (around 1380) , around 1510. File:Pursuivant tabard.jpg, upTabard worn by an English herald in the College of Arms A herald, or a herald of arms, is an officer of arms, ranking between pursuivant and king of arms. The title is commonly ...

herald
s during the sixteenth and seventeenth centuries. The purpose of these
heraldic visitation, undertaken by Ulster King of Arms Daniel Molyneux in February 1607 Heraldic visitations were tours of inspection undertaken by King of Arms, Kings of Arms (and more often by junior officers of arms (or Heralds) as deputies) throughout England ...
s was to register and regulate the use of
coats of arms A coat of arms is a heraldic visual design on an escutcheon (i.e., shield A shield is a piece of personal armour held in the hand, which may or may not be strapped to the wrist or forearm. Shields are used to intercept specific attacks, ...
. Those who claimed the right to bear arms had to provide proof either of a grant of arms to them by the College, or of descent from an ancestor entitled to arms. It was for this reason that pedigrees were recorded by the visitations. Pedigrees continue to be registered at the College of Arms and kept up to date on a voluntary basis but they are not accessible to the general public without payment of a fee. More visible, therefore, are the pedigrees recorded in published works, such as
Burke's Peerage Burke's Peerage Limited is a British genealogy, genealogical publisher founded in 1826, when Irish genealogist John Burke (genealogist), John Burke began releasing books devoted to the ancestry and heraldry of the peerage, baronetage, knightage ...
and Burke's
Landed Gentry The landed gentry, or the ''gentry'', is a largely historical Social structure of the United Kingdom#History, British social class of landowners who could live entirely from rental income, or at least had a Estate (land), country estate. While ...
in the United Kingdom and, in continental
Europe Europe is a continent A continent is one of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, up to seven regions are commonly regarded as continents. Ordered from largest ...

Europe
by the
Almanach de Gotha The ''Almanach de Gotha'' (german: Gothaischer Hofkalender) is a directory of Europe's royalty Royalty may refer to: * Kingship * Royal family, the immediate family of a king or queen regnant, and sometimes his or her extended family * Royalty ...
. A pedigree may be used to establish the probability of a child having a particular disorder or condition. It may be used to discover where the genes in question are located (x, y, or autosome chromosome), and to determine whether a trait is dominant or recessive. When a pedigree shows a condition appearing in a 50:50 ratio between men and women it is considered
autosomal An autosome is any chromosome that is not a sex chromosome (an allosome). The members of an autosome pair in a diploid Ploidy () is the number of complete sets of chromosome A chromosome is a long DNA molecule with part or all of the ...
. When the condition predominantly affects males in the pedigree it is considered
x-linked Sex linkage describes the sex-specific patterns of inheritance Inheritance is the practice of passing on private property, titles A title is one or more words used before or after a person's name, in certain contexts. It may signify eithe ...
. Some examples of dominant traits include: male baldness, astigmatism, and dwarfism. Some examples of recessive traits include: small eyes, little body hair, and tall stature.


In animal husbandry

Image:Pedigree-sh-1895.jpg, Pedigree of horse Shagya IX b. 1895 In the practice of selective breeding of animals, particularly in animal fancy and livestock, including
horse The horse (''Equus ferus caballus'') is a Domestication, domesticated odd-toed ungulate, one-toed ungulate, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two Extant taxon, extant subspecies of wild horse, ''Equus ferus' ...

horse
s, pedigree charts are used to track the ancestry of animals and assist in the planning of suitable breeding programs to enhance desirable traits. Breed registry, Breed registries are formed and are dedicated to the accurate tracking of pedigrees and maintaining accurate records of birth, death and identifying characteristics of each registered animal.http://research.vet.upenn.edu/pennhip/OwnerBreederInformation/SelectiveBreeding/tabid/3350/Default.aspx


See also

* Ahnentafel * Cousin chart#Relationship charts, Cousin chart * Family tree * Genealogical numbering systems * Genogram * Foundation bloodstock * Certificate of Degree of Indian Blood


References

{{Family Classical genetics Diagrams Family trees