《遗传性疾病》PPT课件

Genetic Disorders
(Inherited Diseases)
Zou Xiao-bing Department of Pediatrics 3rd Affiliated Hospital Sun Yat-sen University
Great changes in medicine
one of the biggest victories in medicine over the past 100 years is that infectious diseases have decreased dramatically, for example, smallpox was eradicated, poliomyelitis will soon be eradicated and pertusis, diphtheria, malaria, measles are diminishing
The reasons of the changes in medicine
Social progress planned immunization Advances in medical sciences better nutrition
genetic disorders are increasing
X-linked dominant inherited diseases G-6PD deficiency, vit-D resistant rickets X-linked recessive inherited diseases hemophilia、 Y-linked trait: hairy ear syndrome
A genetic disorder is an illness caused by abnormalities in genes or chromosomes. While some diseases, such as cancer, are due in part to a genetic disorders, they can also be caused by environmental factors.
Treatment of genetic disorders
Most genetic disorders couldn’t be cured. better care from family better welfare of the society function training gene therapy has show us a bright future, ADA(Adenosine Deaminase) deficiency, can be treated by gene therapy. (bone marrow transplantation and stem cell transplantation belong to gene therapy,ßthalassemia can be treated by BMT)
Manifestation of Down Syndrome
Facial abnormalities:small head,recessed nose, small ears and mouth mental retardation:IQ score less than 60 development delayed ,short statue , obesity, fingers are short and stubby, simian crease on the palm congenital heart disease and other malformations can be found in most cases.
Basic of genetics
chromosomes exist in pair, so genes exist in pair. Paired genes could be divided into dominant gene and recessive gene. traits are controlled by the genes One gene one enzyme theory the abnormal chromosomes and genes result in genetic disorders.
Manifestation of genetic disorders
Features in common:mental retardation、 developmental delay, simian crease and abnormal dermatoglyphics , microcephaly and macrocephaly ,abnormal of genital organs,malformation of limb and extremities, spine and anal abnormal specific features:fair skin and unpleasant odor of PKU, White skin of albinsim, facial abnormalities of Down syndrome and thalassemia
Prevention of genetic disorders
Genetic counseling, marriage guidance and risk assessment find the carrier of the parents with abnormal gene prenatal diagnosis by amniocentesis and chorionic villous biopsy
Diagnosis approaches of genetic disorders
Samples used blood amniotic fluid skin hair different kind of cells approaches chromosome analysis biochemical test Enzyme analysis gene analysis pedigree analysis dermatoglyphics
DOWN SYNDROME
First described by John Langdon Down in 1866, the syndrome is named after him. in 1956, Tijo found human cell contained 46 chromosomes. In 1959, Lejeune identified the underlying chromosomal abnormality of affected individuals having a additional #21 chromosome. It is the commonest chromosomal disease. Maternal age is linked to the syndrome.
Basic of genetics
Cell is the basic unit of human body. Chromosome is the carrier of inheritance and gene. Normal cell contain 23 pairs chromosomes, with about 30,000 structural genes
Classification of genetic disorders
Chromosomal abnormalities: including euploid ,21 trisomy, 45,XO(turner syndrome) and structure abnormal such as 5P- and 14 ring. Gene diseases including single gene diseases such as PKU and polygenic diseases such as diabetes.
Classification of single gene inherited diseases
Autosomal dominant inherited diseases brachydactyly、thalassemia, marfan syndrome Autosomal recessive inherited diseases PKU、albinism
Epidemiology of genetic disorders in China
It is estimated that ,each year in China , there are 20,000,000 live birth neonates. 5% of them will suffer from inherited disorders or birth defects. it means that each year there are 1,000,000 new patients. Over 10,000 kind of inherited diseases are found by now.
Treatment of some single gene diseases
Restrict specific food (Dietary restriction) : PKU-phenylalanine, G6PD deficiency-broad bean and aspirine Discharge harmful substances ( wilson disease-copper, thalassemia-iron); Supply lacking substances (hemophisons