The importance of determining carrier status in Duchenne's and Beker's muscular dysrophy in the population of Serbia

[J. M. Maksić]

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Medicina - Genetika / Medicine - Genetics

Distrofinopatije su bolesti koje nastaju kao posledica mutacija u genu za distrofin. Dišenova mišićna distrofija (DMD) predstavlja najteži oblik iz ove grupe bolesti. Karakteriše je rani početak bolesti, progresivna mišićna slabost koja dovodi do gubitka pokretljivosti bolesnika i kardio-pulmonalne slabosti zbog zahvatanja srčanog i respiratornih mišića. Bekerova mišićna distrofija (BMD) se javlja kasnije, ima blaži tok bolesti, ali sa velikom varijabilnošću u kliničkoj slici. Nasleđujuju se X-vezano recesivno, oboljevaju muškarci dok su žene uglavnom zdravi prenosioci bolesti. Procenjeno je da su 2/3 majki nosioci, 5-10% ima gonadni mozaicizam, dok 25-30% nema mutaciju. Gen za distrofin (DMD gen) je najveći opisani gen u humanom genomu i često je podložan promenama. Najčešće su prisutne intragenske delecije (65%-70%) i duplikacije (5-15%) jednog ili više egzona, dok su tačkaste mutacije prisutne u 20% slučajeva. 1/3 bolesnika ima de novo mutaciju. Za sada nema uspešne terapije distrofinopatija, pa je utvrđivanje statusa nosioca kod ženskih članova u familiji od značaja za davanje genetskog saveta i prenatalnu dijagnozu. Cilj rada je bio da se utvrde i analiziraju delecije i duplikacije u genu za distrofin kod probanada; da se u slučajevima potvrđenih delecija i duplikacija kod probanada utvdi status prenosioca kod njihovih ženskih srodnka; u slučajevima bez dokazanih delecija i duplikacija kod probanada, da se ispita mogućnost indirektne genetičke analize za određivanje statusa ženskih prenosioca; da se u indikovanim slučajevima izvrši prenatalna molekularno genetička analiza DMD gena, primenom adekvatne metode za datu porodicu. Material i metode: Uzorak su činila 72 DMD/BMD probanda, 69 ženskih članova iz 44 porodice probanada i 11 trudnica (15 trudnoća). Genomska DNK za analizu je izolovana iz limfocita periferne krvi ispitanika metodom isoljavanja prema standardnoj proceduri, a za prenatalnu dijagnozu, DNK je izolovana iz uzorka horionskih resica, plodove vode ili krvi pupčanika ploda primenom komercijalnog kita. Za detetekciju delecija i duplikacija u DMD genu kod probanda primenjene su metoda lančane reakcije polimeraze (PCR) i metoda istovremenog umnožavanja vezanih proba (MLPA); za detekciju ženskih nosioca primenjene su MLPA metoda i analiza vezanosti; za prenatalnu dijagnozu primenjene su PCR metoda, analiza vezanosti i MLPA metoda...

Dystrophinopathies are diseases that result from mutations in the dystrophin gene. Duchenne muscular dystrophy (DMD) is the most severe form of this group of diseases. It is characterized by an early onset of the disease, a progressive muscle weakness that leads to loss of mobility of the patient, spreading to the heart and respiratory muscles, causing cardio-pulmonary weakness. Becker muscular dystrophy (BMD) occurs in late childhood or adolescence, has a milder course of the disease, but with widely variable clinical presentations. It has an X-linked recessive inherited pattern, whereby males are affected, while females are mostly healthy carriers of the disease. It is estimated that 2/3 of the mothers are carriers, 5-10% have gonadal mosaicism and 25-30% have no mutation. The gene for dystrophin (DMD gene) is the largest known gene in the human genome and is often subject to change. The most common changes are intragenal deletions (65% -70%) and the duplication (5-15%) of one or more exons, as well as point mutations in 20% of cases. 1/3 of patients have de novo mutation. There is no successful therapy for dystrophinopathy, therefore the detection of female carriers in a family is important for genetic counseling and prenatal daignosis. The aim of work was to determine and analyze the deletions and duplications of the dystrophin gene in probands; in the cases of confirmed deletions and duplications in the trial, to determine the status of the carrier in their female relatives; in the cases with no proven deletions and duplications in the trial, the possibility of indirect genetic analysis for determining the status of female carriers; in the indicated cases to perform prenatal molecular genetic analysis of the DMD gene, using an appropriate method for a particular family. Material and methods: The sample consisted of 72 DMD/BMD probands, 69 female members from 44 proband families and 11 pregnant women (15 pregnancies). The genomic DNA for analysis was isolated from the peripheral blood lymphocytes of the subjects, according to the standard procedure, and for prenatal diagnosis, the DNA was isolated from the sample of chorionic villi, amniotic fluid or blood of the umbilical cord using a commercial kit. For the detection of deletions and duplications in the DMD gene, polymerase chain reaction (PCR) method and multiplex ligation-dependent probe amplification (MLPA) method were applied; for the detection of female carriers, the MLPA method and linkage analysis were used; for prenatal diagnosis, the PCR method, linkage analysis and MLPA methods were applied...

distrofinopatije, mutacije u DMD genu, ženski nosioci, prenatalna dijagnoza

dystrophinopathies, mutations in DMD gene, female carrier, prenatal diagnosis

616.8-053.2:577.2(043.3)

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