Mendel´s principles in human genetics deti Peculiarities of genetic studies in humans lEthical standards forbids experiments and selection in human beings lHumans have usually small number of offsprings lPhenotype is influenced by external conditions - polygenic traits lGeneration period is too long – max 4 generations for 1 scientists lComplexity of human genome lHistorically, the mating was limited to individuals in certain population (nation, religion..) x huge number of means of transport = migration nowadays l Fridrich I Prussian had searched tall women for mating with tall men in order to produce royal guard soldiers Directed mating in humans? Archibald Garrod – physician, verified Mendel´s principles by connecting the incicndece of metabolic abnromalilites and mutant recessive alleles (1910) – dysfnuction of enzymes! Alkaptonuria Albinism Cystinuria Pentosuria SCAN363a aa Genes have influence on chemical basis of individuals… Recessive allele = enzyme non-functional! Alkaptonuria – frequent in offsprings with parent blood relative parents! Trait has inheritance according to Mendel´s rules for recessive traits Homogentisic acid in urine alkaptonuritic patient Enzymopaties C:\___allimages\logos_posters\HGPlogosm.jpg In 2003 was HGP finished. Human genome consists of 3 billion base pairs m 232-1-med.gif nature Genotypes of individuals of same kind can be different diversity of the genome Genome of the individuals of the given kind is the same 98% of human genome is non protein-coding! > 50% of genome is consisted of repetitive sequences Organization of the human genome. | Download Scientific Diagram Variability of human genome on DNA level 1000 Genomes Project Consortium •typical genome differs from the reference human genome at 4.1 million to 5.0 million sites •99.9% of variants consist of SNPs and short indels, •structural variants affect more bases: the typical genome contains an estimated 2,100 to 2,500 structural variants: affecting cca 20 million bases of sequence ! Nature 256, October 2015 n2504 genomes sequenced from individuals from various areas of Earth (26 populations) n88 million of genetic variants n84,7 million SNP – single nucleotide polymorphisms n3,6 million indels n60 000 SV – structural variants Single change on DNA level can cause genetic disease! Genetically determined pathologies in humans lvarious disorders of mental and physical development are found in about 5% of newborns lApprox. 0,6 - 0,7 % population has congenital chromosomal aberration l approx. 0,36 % newborns is born with monogenic diseases, which will manifested in 90% of cases in pubertal age l lPrimary cause of genetically-based diseases is change of DNA in form of mutation or pathological variant Types of genetic diseases 1.Monogenic diseases (AD, AR, sex-linked) 2.Chromosomal aberrations 3.Complex diseases with multifactorial type of inheritance (diabetes, allergies) 4.Genetic aberrations in somatic cells (tumors) 5.Mitochondrial genetic diseases 6.Non-mendelian inheritance diseases (uniparental disomy, unstable trinucleotide expansions l Genetics, medical genetics and medicine l lNowadays, in CR are departments of medical genetic parts of most of the big hospitals in – Praha, Brno, Olomouc, Ostrava, Plzeň, Hradec Králové, České Budějovice lAlso private companies in a form of private genetic laboratories Medical genetics is widespread, multidisciplinary field of preventive medicine l lMedical genetics is any application of genetic principles to medical practice. This includes studies of inheritance, mapping disease genes, diagnosis and treatment, and genetic counseling. l l1969 – Medical genetics recognized as standalone medical field in Czechoslovakia l lThe most of the diseases has any genetic background lIn EU, disease is called „rare“ when incidence is less than 5 / 10 000 individuals lEncompass a wide range of conditions, such as movement disorders, metabolic diseases, neurological diseases or retinal dystrophy lMost of them lack an effective treatment = traumatization of parents, whole families https://www.mdpi.com/files/multidisciplinary_topic_graphical_abstract/429/Graphical%20Abstract_def. png https://www.mdpi.com/files/multidisciplinary_topic_graphical_abstract/429/Graphical%20Abstract_def. png Dpt. Of Medical Genetics, Univeristy Hospital Brno www.fnbrno.cz/olg Ambulance 1 Cytogenetika IMG_3712 IMG_3760 IMG_3762 lPatients of DMG - children l l lChildren with inherited neurodevelopmental disorders and their families l lChildren with suspicious or verified inherited diseases and their families (cystic fibrosis) l lChildren with suspicious or verified inherited aberration of metabolism with and their families l lChildren with suspected incidences of inherited chromosomal aberration including stigmatization, development delays, early births, telomery-deti Patients of DMG - adults lBlood relative pairs l lIndividuals with long-term persons exposed for long periods to environmental pollutants l lPairs treated with infertility or repeated spontaneous aborts l lSperm and egg donors l Patients of DMG – pregnant women lPositive familial anamnesis (in/dysferility, aborts, NDDs..) lUnfavorable anamnesis during pregnancy (long disease or acute diseases, medical treatments, vaccinations, addictive substances) lPathological finding in biochemical or ultrasound screening lOlder than 35 years lBirth of dead fetus or exitus of newborn lParents are carriers of balanced translocation l l l images Genetic counselling lperformed by a physician - geneticist la medical profession dedicated to the care of patients with genetic diseases and their families. lclinical geneticists provide the necessary laboratory diagnostics, identify patients who are at increased risk of developing or transmitting a genetic disease. lcombines the determination of the risk of disability of the developing individual with psychological and educational activities - informing the patient and family members lThe main goal of genetic counselling is to answer the question "What is the risk of our child being affected by a hereditary disease?" lThe basic role of genetic counselling is to provide patients with genetic diseases or their relatives with sufficient information about the nature of the condition, its future course, treatment options and, above all, the risk of recurrence in other members of the family. l lto determine the genetic prognosis !!! lgenetic risk (%) - above 10 % unfavorable Genetic counselling in clinical praxis Genetic counselling – gathering of information lPersonal and family anamnesis lGenealogical examination, compilation of at least a three-generation family tree lEthnic information lConsanguinity lNonpaternity Genetic counsellor is dedicated to answer during session following questions: lis the disease occurring in the family hereditary? lwhat is the type of inheritance of the disease in the family? lwhat is the risk of recurrence of the disease in the family? lwhat is the risk of any hereditary disease in offspring? lis it possible to prevent the onset and development of hereditary disease? lis it possible to detect an inherited disease in the fetus during pregnancy? lis it possible to detect hereditary disease before pregnancy? lcan the disease be treated? Take care ! l l inherited l congenital (de novo?) l familial (genetic and enviromental origin) Diagnostic approaches lMethods of clinical genetics l lPedigree analyses l lLaboratory techniques lCytogenetics - karyotypes, FISH…. lDNA or RNA diagnostics \\10.2.30.220\olg\Laboratore\Integrovana laborator molekularni cytogenetiky\Fotky\fotky strojů labina\Snímek 003.jpg \\10.2.30.220\olg\Laboratore\Integrovana laborator molekularni cytogenetiky\Fotky\fotky strojů labina\Snímek 010.jpg Clinical-genetic examination lSomatic abnormalities - stigma lCongenital developmental defects e.g. malformations (e.g. cleft palate), dysplasia - abnormalities of certain tissues lPsychomotor development lMental retardation lDermatoglyphics Pedigree analysis lAnalysis of pedigrees it is possible to find out: lincidence of hereditary diseases in the l family ltype of heredity ldiagnosis lprobability of disability in descendants or relatives - genetic prognosis linfluence on treatment (preventive examinations...) l l l l l Symbols commonly used for pedigree analysis. - American ... Example of pedigree l Exploring Genetics by Creating a Family Pedigree - Kristin Moon Science https://kristinmoonscience.com/wp-content/uploads/2019/11/Incomplete-pedigree-of-left-handed-trait. png Monogenic diseases(DNA mutation at the level of one gene - change of gene product ! l- Autosomal dominant - AD l- Autosomal recessive - AR l- X-linked recessive - XR l- X-linked dominant - XD l Types of inheritance Most monogenic inherited diseases manifest themselves before birth, early after birth or in childhood Mendelian inheritance is characteristic ! příklady 11.1 BASIC PATTERNS OF HUMAN INHERITANCE - ppt video online download https://slideplayer.com/slide/6199975/18/images/16/%EF%83%96RECESSIVE%2FDOMINANT+GENETIC+DISORDERS. jpg l Pedigree - example of autosomal dominant inheritance snu5e_fig_03_13b Affected gene product: mostly proteins of morphological and structural character biological carriers, cell receptors • Autosomal dominant inheritance (AA, Aa – affected, aa- healthy) lThe MOST COMMON TYPE of disease inheritance in humans lvertical type of inheritance ldominant allele lies on the autosome - males and females equally affected lsex ratio 1:1 lheterozygotes are also affected - clinical manifestation = 1 copy of the gene lthe affected person has one parent equally affected l50% risk of recurrence for offspring and siblings of the affected person l- healthy family members usually have healthy children Aa x aa AA x aa Aa X Aa The most common case Polydactyly – AD inhertiance Exome sequencing revealed a splice site variant in the IQCE gene underlying post-axial polydactyly type A restricted to lower limb | European Journal of Human Genetics https://media.springernature.com/m685/springer-static/image/art%3A10.1038%2Fejhg.2017.83/MediaObjec ts/41431_2017_Article_BFejhg201783_Fig1_HTML.jpg Achondroplasia – AD ihneriatnce lAchondroplasia is a genetic bone disease that accounts for a person's short stature l ltranslated from Greek, it means insufficient cartilage formation lthe gene responsible for this disease was discovered in 1994 : mutation in the fibroblast growth factor receptor 3 (FGFR3) gene lit is a congenital skeletal disorder larms and legs are shorter than the trunk and the head circumference increases unusually rapidly in the first few months of life. lOther symptoms include lower muscle tension, higher joint extensibility, and susceptibility to upper respiratory tract infections and otitis media lBecause of their short limbs, people of small stature have to exert themselves a lot when walking, so many of them develop various degrees of bowing of the legs at school age. Marfan syndrome – AD inheritance l abraham-lincoln1 ? lIncidence 1:5-10000 lmutation of FBN1 – protein fibrilin 1 – a component of connective tissue) lgenetic disorder of connective tissue - ligament lskeletal abnormalities ltall stature, long thin limbs llong thin fingers (arachnodactyly) lanomalies of the heart and blood vessels Marfan syndrome – N. Paganini? Pedigree - example of autosomal recessive inheritance l snu5e_fig_03_13c Aa Autozomal recessive inheriatnce (aa – affected) ! lAa - health - the standard heterozygote allele is able to compensate for the mutant allele lmutant recessive allele on the autosome l1:1 sex ratio l horizontal type of inheritance l sibling risk 25% (Aa x Aa) ldisability only occurs in homozygotes l more common in consanguineous marriages Aa x Aa...1/4 affected Aa x aa...1/2 affected aa x aa...all affected The most common type of parent....carriers ! The risk of a carrier having a disabled child depends on the likelihood that his partner is also a carrier Genotypes AR inheritance - example Metabolic dysfunctions lEnzymopathies – enzyme disorder: almost always AR, l heterozygotes with 50% residual allele activity are clinically normal (Aa) l lMetabolic blockades - all pathophysiological consequences of enzymopathies can be attributed to substrate accumulation or product deficiency lSubstrate product l lDisorders of metabolism of lamino acids, sugars, lipids, lpurines, pyrimidines, etc.) l l(phenylketonuria, alkaptonuria, albinism, galactosemia) enzyme Normal adult haemoglobin (HbA) consists of 4 subunits, two alpha (α) and two beta (ß - 146 AA). each subunit is composed of a protein part, globin, and a prosthetic (non-protein) part, HEME group AR inheritance – sickle cell anemia mutation HbA HbS https://upload.wikimedia.org/wikipedia/commons/a/ac/Sickle_cell_01.jpg Mechanism Mutation T – A causes change in AA sequnece: GLU - VAL Substitution of CTT for CAT in sickle cell anemia in the beta chain of hemoglobin leads to substitution of one amino acid joining the polymeric fibers the sickle-shaped form blood cells HbA/HbA homozygotes - normal HbA/HbS heterozygotes HbS/HbS - sickle cell anaemia (microcirculation disorders, capillary blockage, bone marrow infarction, tissue damage) 1 : 600 Afican Americans HbA/HbA : HbA/HbS 1, 46 : 1 The mutant allele still persists in the population...? Rozšíření srpkovité anémie https://i.pinimg.com/originals/64/e0/e7/64e0e7b2ccdfe903b63be0a27666a11d.png Cystic fibrosis – AR inheritance lone of the most common in Caucasians (predominant disease in Northern Europeans !!!) l lbasis - mutation in the CFTR gene, range about 250 kb, coding region with 27 exons lgene discovered in 1989 (7q31) lincidence in the Czech Republic about 1/2000 - 1/3000 lfrequency of carriers in the Czech Republic about 1/25-1/29 lmean age at diagnosis 6-8 months, 66% of patients under 1 year lseverity is limited mainly by lung involvement.... lmedian survival in 1976 - 18 years, in 1995 - 30 years, very little improvement since 1990, now new drugs? CF - pathophysiological defect - impaired ION TRANSPORT in epithelial cells Photograph of the middle transverse section of the lung in a patient with CF (mucus plugs in the lungs) CFTR protein - chloride channel - regulates the flow of salts and water CF - mutation - the channel is missing or non-functional ! What is cystic fibrosis? – YourGenome Cystic Fibrosis: Signs, Symptoms, and Complications Cystic fibrosis How to Help Your Child With Cystic Fibrosis – Cleveland Clinic CF – mutation types in Europe A retrospective study of cases diagnosed with cystic fibrosis at a single care center in Syria | Egyptian Journal of Medical Human Genetics | Full Text lhttps://media.springernature.com/lw685/springer-static/image/art%3A10.1186%2Fs43042-021-00178-5/Me diaObjects/43042_2021_178_Fig2_HTML.png labout 2000 mutations have been detected in the CFTR gene...!!!! lthere are 5 classes of mutations...different severity of disability lonly 7 mutations above 1% of CF patients Patients: 50% homozygous for dF508/dF508 40% compound heterozygous - dF508 and other mutant allele A standard.... a1 a2 a3 ... mutations a1a2 a1a3 ... patients Allelic heterogeneity ! Higher concerntartion of NaCL in sweat…. „Salty children“ 27 Cystic Fibrosis ideas | cystic fibrosis, cystic fibrosis awareness, cystic fibrosis quotes l Cystic fibrosis CF. Cysticfibrosis Cystic fibrosis the most common autosomal recessive (AR) disorder among Caucasians chronic and progressive disease. - ppt download https://images.slideplayer.com/19/5867314/slides/slide_5.jpg The most common CFTR gene mutations in the Czech population - allelic heterogeneity - multiple mutations at the same locus = composition of heterozygotes l1. dF508 68,8% 10 l2. CFTRdele 2,3 (21kb) 4,64% 2, 3 l3. G551D 4,03% 11 l4. N1303K 3,02% 21 l5. G542X 2,22% 11 l6. 1898+1 G-A 2,04% intron l7. 2143delT 1,11% 12 l8. R347P 0,74% 7 l9. W1282X 0,55% 20 l10. E92X 0,37% 4 l11. R1162X 0,37% 19 MUTATION FREQUENCY IN CF PAC. EXON (26) Frontiers | CFTR Modulators: Shedding Light on Precision Medicine for Cystic Fibrosis A commentary on the novel complex allele [A238V;F508del] of the CFTR gene: clinical phenotype and possible implications for cystic fibrosis etiological therapies | Journal of Human Genetics CF newbron screening lDefinition of NS lThe active, nationwide search for a disease in the population of all newborns in its preclinical stage so that these diseases are diagnosed and treated before they have time to manifest and cause irreversible damage to the newborn's health l lAs of October 2009, 13 diseases are being screened for as part of newborn screening in the Czech Republic l (CF, phenylketonuria, hyperphenylalaninemia, …) lSearching by laboratory method - the principle of analysis of a so-called dry drop of blood on filter paper taken in a standard way l Blood aspiration for newborn screening zápis0021 zápis0022.jpg zápis0023.jpg zápis0025.jpg Causal treatment of CF – new drugs? Molecular therapy of CF lIvacaftor lLumacaftor lSymdeko How SYMDEKO® (tezacaftor/ivacaftor and ivacaftor) Works CFTR corrector (1) and potentiator (2) modulators work together to... | Download Scientific Diagram X-linked recessive inheritance lSex chromosomes: women XX, men XY l lthe affected person is usually a man, his sons are healthy and his daughters are carriers of the disease lfemale carriers have 1/2 sons who are sick and 1/2 daughters who are carriers lrare occurrence in women - daughter of affected man and female carriers, women with karyotype 46,XaXa 45,Xa, ... lexample - haemophilia A a a Hemizygoteous state Pedigree of X-linked recessive disease Some X-Linked Recessive Disorders Seen in Pediatric Patients | Download Table Haemophilia rare congenital bleeding disorder that occurs in people with a limited amount of either clotting factor VIII/ 8 (haemophilia A) or clotting factor IX/ 9 (haemophilia B) Severity of haemophilia Percentage of normal factor activity in blood Number of international units (IU) per millilitre (ml) of whole blood normal range 50%-150% 0.50–1.5 IU mild haemophilia 5%-40% 0.05–0.40 IU moderate haemophilia 1%-5% 0.01–0.05 IU severe haemophilia less than 1% less than 0.01 IU Hemophilia a and hemophilia B: different types of diseases? | Semantic Scholar Haemophillia – clinical features A Royal Disease Queen Victoria of England, who ruled from 1837-1901, is believed to have been the carrier of hemophilia B, or factor IX deficiency. She passed the trait on to three of her nine children. l Queen Victoria Kinship crossing - consanguinity Parental consanguinity in Hong Kong | HKMJ Inbreeding linbreeding occurs when parents have common ancestors and are therefore related to each other. lInbreeding between relatives is referred to as consanguinity from the Latin term "of the same blood„ lexample - crosses between siblings, half-siblings and first cousins - the offspring are inbreed linbreeding increases the frequency of homozygotes and decreases the frequency of heterozygotes and is quantified by the inbreeding coefficient F l l l l l l lF value range from 0 to 1 1 = all alleles have same origin F = probability that an individual has two copies of the gene identical in origin (autozygous) because they come from a common ancestor (if they are identical, the individual is homozygous) Part of Ptolemy peidgree SCAN360o img008 Common ancestor snu5e_fig_04_17 Incidence of albinism in Amish community Habsburgs - frequent hereditary mental and psychological illnesses due to consanguineous marriages l 2327849--johana-silena-nositelka-geneticke-zateze-habsburskeho-rodu--1-300x265p0 Joanna of Castile (Mad) Married with Habsburg 1496 2327855--filip-i-slicny-manzel-johany-silene--1-239x300p0 Philip I (Handsome) Archduke of Austria What destroys House of Habsburgs? Inbreeding lIn the Habsburg dynasty, uncles and nieces, aunts and nephews, as well as cousins often married each other. The so-called inbreeding coefficient, which is a measure of how closely related individuals are. l lWhile the first Spanish king of the Habsburgs, Philip I the Magnificent, had an inbreeding coefficient of 0.025 - meaning that 2.5% of his genes were identical to those of his relatives. Seven generations and 200 years later - in the case of Charles II - the inbreeding coefficient was already tenfold, i.e. 0.25 (25%!!!) l