Chromosomal disorders http://web.udl.es/usuaris/e4650869/docencia/GenClin/content/recursos_classe_(pdf)/revisionsPDF/chromosyndromes.pdf

Body, cells, chromosomes 23 pairs of chromosomes + mitochondrial DNAs Human body: 10 trillion cells

karyogram Cytogenetics - karyotype Giemsa staining

Homologous chromosomes Daughter chromosomes Sister chromatids

Meiózis I Meiózis II n: number of chromosomes c: number of chromatids

Nondisjunction in meiosis MEIOSIS - I MEIOSIS - II FERILIZATION ZYGOTE Disjunction = separation

Chromosomal aberrations Structural disorders translocations Insertions/ deletions duplications inversions Ring chromosomes Numerical disorders Aneuploidy Hyperploidy Trisomy (2n+1) Tetrasomy (2n+2) Hypoploidy Monosomy (2n-1) Nullisomy (2n-2) Euploidy Monoloidy (n) Diploidy (2n) Polyploidy (3n,4n,etc.) Chromosomal aberrations Aberration in a cell vs. in every cell of an organism

Numerical aberrations Autosomes Patau-syndrome (13-trisomy) Edwards-syndromes (18-trisomy) Down-syndrome (21-trisomy Sex chromosomss Turner-syndrome (X0) Triple X syndrome (XXX) Klinefelter syndrome (XXY) Double Y syndrome (XYY)

Patau-syndrome (trisomy 13) A chromosomal condition associated with severe intellectual disability and physical abnormalities in many parts of the body. Affected individuals with this disorder often have brain or spinal cord abnormalities, heart defects, poorly developed eyes, extra fingers or toes, an opening in the lip frequently associated with an opening in the roof of the mouth, and weak muscle tone (hypotonia). Many infants with trisomy 13 die within their first days or weeks of life. Only 5 to 10 percent of children with this condition live past their first year. occurrence: 1/16,000

Edwards syndrome (trisomy 18) This chromosomal condition may be associated with heart defects and abnormalities of other organs. Other features include a small, abnormally shaped head; a small jaw and mouth; and clenched fists with overlapping fingers. Most affected individuals die before birth or within their first month. 5 to 10 % of children with this condition live past their first year, and these children often have severe intellectual disability. Occurrence: 1/5,000

Down-syndrome (trisomy 21) This syndrome is associated with a characteristic facial appearance, and hypotonia in infancy. Affected individuals experience cognitive delays, but the intellectual disability is usually mild to moderate. About half of all affected children are born with a heart defect. Individuals with Down syndrome also have an increased risk of hearing and vision problems. occurrence: 1/800

Turner syndrome (X0) The most common feature of this syndrome is short stature. Many affected girls do not undergo puberty unless they receive hormone therapy, and most are infertile. Turner syndrome occurs in about 1 in 2,500 newborn girls worldwide.

Triple X syndrome (XXX) Most females with triple X syndrome are able to conceive children. This condition is associated with an increased risk of learning disabilities and delayed development of speech and language skills. Delayed development of motor skills, hypotonia, and behavioral and emotional difficulties are also possible. This syndrome occurs in about 1 in 1,000 newborn girls. Four or even more X chromosome can also occur.

Klinefelter syndrome (XXY) This disease affects male physical and cognitive development. Affected individuals typically have small testes that do not produce as much testosterone as usual. A shortage of testosterone can lead to delayed or incomplete puberty, breast enlargement, reduced facial and body hair, and infertility. have an increased risk of developing breast cancer and a chronic inflammatory disease. Children with Klinefelter syndrome may have learning disabilities and delayed speech and language development. Klinefelter syndrome affects 1 in 500 to 1,000 newborn males.

Double Y syndrome(XYY) Males with this condition may be taller than average, this chromosomal change typically causes no unusual physical features. Most males with 47,XYY syndrome have normal sexual development and are able to father children. This syndrome is associated with an increased risk of learning disabilities and delayed development of speech and language skills. Delayed development of motor skills, hypotonia, and behavioral and emotional difficulties. This syndrome occurs in about 1 in 1,000 male birth.

Structural abnormalities Two chromosome mutations Single chromosome mutations insertional translocation https://en.wikipedia.org/wiki/Chromosome_abnormality deletion duplication inversion ring chromosome isochromosome reciprocal translocation

Chromosomal deletion syndromes Wolf–Hirschhorn syndrome (4p16.3) Jacobsen syndrome (11q24.1) https://en.wikipedia.org/wiki/Wolf%E2%80%93Hirschhorn_syndrome Chri du chat szindróma (5p15.1)

Chromosomal duplication syndromes Charcot–Marie–Tooth disease Mutations on various chromosomes can cause the disease https://en.wikipedia.org/wiki/Wolf%E2%80%93Hirschhorn_syndrome 1q21.1 duplication syndrome

Nondisjunction in mitosis It causes mosaicism

Chromosomal mosaicism http://www.alzforum.org/news/research-news/could-genetic-mosaicism-adult-neurons-precipitate-disease

Genetic mosaicism in the brain Not only chromosomal mosaicism! http://www.alzforum.org/news/research-news/could-genetic-mosaicism-adult-neurons-precipitate-disease