Enzymopathy – Inherited Metabolic Disorders RNDr Enzymopathy – Inherited Metabolic Disorders RNDr. Hana Zoubková, PhD Energy -228

substrate product Mutation in nuclear DNA Mutation in mitochondrial DNA Dysfunctional enzyme, protein substrate product Multi-organ failure

General characteristics Inherited metabolic disorders caused by enzyme disorders hereditary type recessive – Heterozygotes Aa with 50% residual activity of enzyme are clinically normal. diffused versus macromolecular substrates – Macromolecular s. are only in the tissue, where the substrate is accumulated. acumulation of substrate (1), deficit of product (2) of origin of toxic substances, (3) or combination Diffuse-derivatives are moving in the body and are damaging the cells that have no relationship to the metabolic pathway In certain metabolic pathway

General consequences 1. the accumulation of molecules proteins, enzyme, which is not eliminated and excluded in the right way 2. the absence of the protein molecules, enzyme or other substances in the organism 3. the formation of by-substances (proteins, enzymes, or other substances), which do not belong to the body, and cause acute or slow poisoning

General characteristics A single patient may have a loss of more than one enzyme.  They share the same cofactor, a common activator, modifying or stabilizing protein; may be missing a whole group of enzymes or the entire organelle is abnormal. phenotype homology Diseases are caused by other enzymes, but in the same area of metabolism. The diseases are different, but arise in the partial or complete defect of one enzyme. It does not concern catalytic RNAs.

General characteristics It is currently recognized more than 850 IMD. Approximately 100 of them are curable or controllable by diet. Low-protein, lactose free, gluten free diet Every year is born around 1,000 children with IMD in Czech republic

Inherited metabolic disorders IMD aminoacids: Hyperphenylalaninemia, Tyrosinemia, Alkaptonuria, Homocystinuria, Cystinuria, Cystinosis Leucinosis - Organic aciduria (acidemia) IMD saccharides: Galactosemia, Galactokinase deficiency, Fruktose-intolerance, UDP-Galactose-4-epimerase deficiency, Fructose 1,6-Diphosphatase deficiency, glykogenosis IMD purin/pyrmidin - Porfyria, disorders of urea cycle IMD lysosoms - Tay-Sachs disease peroxisoms, mitochondria (metylmalonová acidurie, propionová acidurie, izovalerová acidurie) Disorders cycle urea

Phenylalanine

Fumarylacetoacetate hydrolase acid oxidase Tyrosinemia, new type Fumarylacetoacetate hydrolase block Tyrosinemia, type I

Hyperphenylalaninemia Is characterized by mildly or strongly elevated levels of the aromatic amino acid phenylalanine in the blood. Are caused by lossing mutations in gene for enzyme phenylalanine hydroxylase (PAH) or in gene for cofactor. Enzyme is necessary for metabolism of amino acid phenylalanine (Phe) to the amino acid tyrosine. Phenylketonuria - PKU Variant PKU Non-PKU losing mutations are mutation leading to loss of function of protein Non/pku Reziduální aktivita fenylalanin hydroxylázy, plazm koncentrace fenylalaninu je pod 1mM, což je10x zvýšený oproti normálu a nižší než u klasické PKU The variant PKU the transition between non-PKU and PKU tetrahydrobiopterin-deficient hyperphenylalaninemia A rarer form PAH is normal, but there is a defect in the biosynthesis or recycling of the cofactor tetrahydrobiopterin (BH4) by the patient This cofactor is necessary for proper activity of the enzyme. The coenzyme (called biopterin) can be supplemented as treatment 10

Phenylketonuria PKU AA phenylalanine accumulates and is converted into phenylpyruvate (phenylketone), which is detected in the urine. It is toxic for the body and causes mental retardation, light pigmentation. Main treatment for classic PKU patients is a strict PHE-restricted diet. chromosome 12q24.1, incidence 1:5 000 a 1:15 000 1:6 000 in Cz It is important for the metabolism glucose and and the synthesis of fatty acids and cholesterol -- lack of myelin packaging For that reason it should be cut meat, milk, cereals, the normal bread, cereal, most confectionery, nuts, leguminous vegetables, in part, the most fruit and vegetables, and food containing artificial sweetener aspartame. The gene for PAH isolated in 1986 per year it is diagnosed about 10 cases 11

- 400 alleles, 6 mutations in each of the 13 exons Alelic heterogenity - 400 alleles, 6 mutations in each of the 13 exons Newborn screening od PKU is included in the panel of most countries. Treatment is the diet – it is effective, if it is launched at birth. Složení heterozygoti Alelic heterogenity - 400 alleles, mostly rare, in each of the 13 exons 6 mutation - 2/3 in European population, the next 6 mutation in 80 % of the Asian population, maternity hospital, birth center nov scree PKU, congenita hypothyroidism, galactosemia, sickle cell disease, cystic fibrosis,

Tyrosine

Fumarylacetoacetate hydrolase acid oxidase Tyrosinemia, new type Fumarylacetoacetate hydrolase block Tyrosinemia, type I

Albinism classical, type IA. lack of product, pigment of skin and hair, achromatosis lack or non-functional tyrosinase Tyrozinase negative Typ IB – tyrozinse is positive, non-active Type II – frequent, tyrozinase positive but with gene mutation Albinism is associated with a number of vision defects, such as photophobia, nystagmus and astigmatism. Lack of skin pigmentation makes for more susceptibility to sunburn and skin cancers. achromia, achromasia, or achromatosis) is a congenital disorder characterized by the complete absence of pigment in the skin, hair and eyes due to absence or defect of tyrosinase, a copper-containing enzyme involved in the production of melanin.

Alkaptonuria - AKU the failure of metabolism of homogentisic acid, Caused by lack of enzyme homogentisate 1,2-dioxygenase, homogentisic acid oxidase (HGD), Accumulation of substrate Homogentisic acid is changed to brown-black pigment – alkapton - excretion to the urine, accumulation in tissues - ochronosis incidence 1 : 250 000 treatment: the limited supply of phenyalanine and tyrosine

Tyrosinemia type I is caused by the failure of tyrosine metabolism, of enzyme fumarylacetoacetate hydrolase (FAH). Accumulation of tyrosine (substrate) and toxic secondary metabolites, mainly for the liver and kidneys Incidence 1: 100 000-120 000 Tyrosinemia type II and III are rare and the level of toxic metabolite sukcinylaceton is not so high. Treatment of alkaptonuria and tyrosinemia by diet and nitison. The most serious the final step in the degradation of tyrosine - fumarylacetoacetate to fumarate, acetoacetate and succinate (especially succinylacetone), clinical symptoms of tyrosinemia type I are very diverse with disabilities

Methionine Cysteine

Degradation of methionine

Homocystinuria Methionine is metabolized to cysteine ​​via homocysteine. ​​ Is caused by the lack of cystathionine β-synthase (CBS), which causes the increased value of homocysteine ​​and methionine in the urine. Accumulation of substrate is harmful for four organ systems: the eye, skeleton, vascular endothelium and central nervous system Essential amino acid with sulfur - in the proteins.  Synthesis is critical in the synthesis of carnitine, taurine, fosphatidylcholinu, phospholipid ........... Hepar, coenzyme A, biotin, glutathione 132 mutations are missense mutations

Ectopia lensis, excessive height, length of limbs, vascular abnormalities

Valine Leucine Isoleucine

Organic aciduria (acidemia) The group of specific enzymes disorders in the catabolism of branched amino acids leucin, valin and isoleucin. Accumulation of toxic organic acids (by-products) causes medium acidification of organism, especially disability of brain. Every year is born 10 patients with one of the organic aciduria in Czech Republic

„Maple syrup urine disease - MSUD“ Or Leucinosis Is the failure of metabolism of branched-chain α-keto acids. The failure of certain dehydrogenase in multienzyme complex Accumulation of keto-acids in the body, accumulation of substrate causes food intolerance, failure to thrive, vomiting, lethargy, and the smell of urine and earwax after maple syrup. 1: 20 000-50 000, Mennonites – 1: 1000 multienzyme complex associated with the inner membranes of mitochondria

Galactose

Galactosemia, classical Is the failure of metabolism of monosaccharide galactose (component of lactose). Toxic by-products of metabolism are toxic to liver, brain, kidneys and eye lens; cause malnutrition, cirrhosis and mental retardation. Galactose-1-phosphate uridyltransferase – GALT (9.chromosome, 160 mutations) 1:18 000 to 1:70 000 In cerebrosids, gangliosids, glykoproteins Accumulation of galactose-1-p, which is further metabolized in alternative way to galaktitol, galakto-1 -phosphate to glukozo-1 –phosphate Galactose is present in all fruit and, in some cereals and vegetables (for example Cabbages, cauliflowers, beet, Brussels sprouts, cabbages, tomatoes and legumes (peas, soya, beans, and lens, etc. ). The patient should be excluded from cocoa, chocolate, creamy ice-cream, almonds, nuts, cinnamon.

Tay-Sachs disease GM2–gangliosidosis Is the failure of degradation of sfingolipid GM2 – gangliosid. It is the hexosaminidase A (HEXA) deficiency, which causes accumulation of substrate. Substrate affects mainly the brain and causes degeneration of nerve system. Syndrome - cherry-red spot on retina increased incidence (1:3600) for ashkenazi Jewish population (1:360 000, chromosome 15) lysosomal disease sfingolykolipid death between 2 to 4 year of life

Porfyria Caused by enzymes deficiencies operating in the synthesis of heme. Defects of enzyme in the early stage cause accumulation of substrate: acid 5-aminolevulinic acid and porfobilinogen Defects in the later stages lead to the accumulation of porfyrinogens - accumulation of substrate and by-products Skin, liver damage congenital erytropoetic porfyria Ad 1- s toxickým účinkem – neuropatie (svalová slabost), abdominální bolest, neklid, hysterie, psychotické stavy. (reakci na viditelné světlo v oblasti 400 nm); při vystavení porfyrinů světlu o této vlnové délce dochází k jejich excitaci, Porfyrinogeny , jejichž oxidační produkty způsobují fotosenzitivitu reakci s molekulárním kyslíkem za tvorby kyslíkových radikálů, které poškozují buněčné organely včetně lysosomů → dochází k uvolnění lysosomálních enzymů, které poškozují světlu vystavenou kůži (erytém, puchýře, jizvení). Akutními porfyriemi jsou častěji postiženy ženy, chronickými muži. nejvíce postižených orgánů produkujících porfyriny Hepatální, erytropoetické, erytrohepatální

Nuclear and mitochondrial heredity Mutated gene in nucleus Mutated gene v mitochondria Combination of maternal and Genetic maternal information paternal genetic information of prokaryotic type - chromosomes Mendel‘s law Maternal line Disability throughout the body Variable expression

Maternal mitochondrial heredity

Mitochondrial diseases are a heterogeneous group with dysfunctions in respiratory chain. They are metabolic disorders and neurodegenerative or muscle diseases. Are caused by the lack of product. Affection is multi-systematic, with exception of LHON Tissue with a high level of requirement of ATP (the brain, muscle, liver, heart, kidney . . .) are affected. popisovány od r. 1988 oxidative phosphorylation, four complexes of respiratory enzymes and complex f1f0 ATP protein

Mutations in mtDNA Variable expresivity typical for mitochondrial disease - distribution to daughter cells is random, distribution of mutated and normal mtDNA is variable Homoplasmy = only mutated or only normal mtDNA in the cell the mixture of normal and mutant mtDNA = Heteroplasmy Prenatal genetic testing and interpretation of test results for mtDNA disorders are difficult

Defect in mitochondrial respiratory chain should be considered for patients, which have any unexplainable combination of neuromuscular and/or different symptoms, with proceeding course and affecting seemingly unrelated organs. Munnich et al, OMMBD, chapter 99

Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) - brain and nervous system (encephalo-) and muscles (myopathy), lactic acid, muscle spasms, impaired muscle coordination (ataxia) Leber hereditary optic neuropathy – LHON - degeneration of retinal ganglion cells, acute or subacute loss of central vision Dědičné metabolické poruchy mitochondrií: Leighův syndrom • Chronická progresivní externí oftalmoplegie • Syndrom Kearns-Sayre • Leberova hereditární optická neuropatie • Maternálně dědičný diabetes a hluchota • Deficit pyruvát dehydrogenázy • Deficit pyruvát karboxylázy • Deficit fosfoenolkarboxykinázy

Association with mutaion (A3243G) mtDNA in gene for tRNA Leu (UUR). MELAS, Association with mutaion (A3243G) mtDNA in gene for tRNA Leu (UUR). Genetický kód mitochondrie a eukarytoního jádra je totožný s vyjímkou čtyř kodónů. 4 triplety mají jiný význam proti jadernému genomu, rozdíly spočívají v iniciaci a terminaci UGA codon is not a termination codon, but codes for tryptophan, on the other hand codons AGA and AGG do not code for leucine, but terminate translation and the codon AUA codes for methionine instead for leucine.

Mutations in mtDNA Mutations cca 10x more often then in nuclear DNA, because histons and some reparation mechanisms are absent. Approximately 10% of all mitochondrial proteins are encoded by nucleus. In case of mutations in these genes - AR heredity Some mitochondrial proteins are aggregates with origin in nucleus and in mitochondria. čerstvé mutace vznikají pravidelně, v dané sekvenci asi 1krát za 1500–3000 let

Thanks for attention Literature Thompson and Thompson: Clinical Genetics, 6. edition, 2004 Adkinson J R, Brown M.D.: Elsevier‘s Integrated Genetics, 2007