Risk For Duchenne Muscular Dystrophy Research Articles

Noninvasive prenatal testing of Duchenne muscular dystrophy in a twin gestation.

Haplotype-based assay has been proved efficient in noninvasive prenatal testing for various monogenic disorders in singleton pregnancies. However, its application in twin pregnancies is still blank. Here we provide a novel algorithmic approach to noninvasively assess fetal genotypes in a dizygotic twin pregnancy at risk for Duchenne muscular dystrophy (DMD). One pregnant woman carrying a dizygotic twin gestation was recruited as she was a heterozygote of DMD gene duplication and has delivered an affected son. Construction of parental haplotypes was achieved by target sequencing of DNA samples from the parent and the proband. Single nucleotide polymorphisms within target regions were classified into six categories according to parental haplotypes. Individual fetal fractions were calculated using paternal heterozygous. Maternal-inherited haplotype was deduced using relative haplotype dosage through a two-step Bayesian model. One male fetus with a lower fetal fraction of 4.6% and one female fetus with a higher fetal fraction of 10.1% were observed. The male fetus was predicted to be a DMD pathogenic variant carrier, while the female fetus was predicted to be homozygous normal. Noninvasive prenatal testing (NIPT) results were concordant with the findings of invasive prenatal diagnosis. This study is the first report of the use of NIPT for the assessment of DMD in a twin pregnancy. The algorithm provided could expand the use of NIPT to monogenic disorders in dizygotic twin pregnancies.

Detection of fetal nucleated red blood cells in the maternal circulation by Kleihauer test

Maternal blood was obtained from 18 pregnant women at 7 to 25 weeks of gestation. After Percoll discontinuous density gradient centifugation, the fetal nucleated red blood cells (NRBCs) were stained with Kleihauer test. Positive fetal cells appeared with an intense red cytoplasmic staining while maternal cells with adult haemoglobin were colourless. Individual positive NRBC was collected by micromanipulator and whole genome amplification was then performed to determine sex and STR status. This allowed the simultaneous verification of the fetal origin of NRBC and prenatal diagnosis of genetic diseases. The non-invasive prenatal genetic diagnosis of 9 fetuses at high risk of Duchenne muscular dystrophy (DMD) was completed successfully. The Kleihauer test is a rapid, simple and direct chemical staining method to select fetal cells and can be applied in prenatal diagnosis.

Genetic counseling for childless women at risk for Duchenne muscular dystrophy.

The aim of the present study was to assess the impact of genetic counseling in young women at risk to have Duchenne muscular dystrophy (DMD) children prior to childbearing. A total of 263 potential DMD carriers, who had had genetic counseling and were given different genetic risks, were included in this investigation. Their reproductive outcome and future plans as well as their requests for DNA tests (for carrier detection and prenatal diagnosis) were analyzed according to genetic risk magnitude, comprehension of genetic counseling is- sues, family and personal history, socio-educational level, and subjective opinion about selective abortion. We noted that genetic risk magnitude had no significant influence on reproductive plans or outcome nor on the request for additional DNA testing, even considering only those clients with good comprehension and retention of issues discussed during genetic counseling. On the other hand, counselees who had more than one affected or at least one deceased DMD case in their family understood genetic counseling significantly better, suggesting that "learning with life" has a stronger impact than genetic counseling.

Immunohistochemical studies show truncated dystrophins in the myotubes of three fetuses at risk for Duchenne muscular dystrophy.

We have performed immunohistochemical studies on muscle tissue of three 12 week old fetuses at risk for DMD, using antisera directed against regions located NH2-proximally and centrally in the rod shaped spectrin-like domain and against the COOH-terminus of dystrophin. All three fetuses had a family history of DMD. Truncated dystrophins were identified in all three cases by a positive reaction with the NH2-proximal antibody, different reactions with the central antibody, and a negative reaction with the COOH-terminal antibody. These data indicate that a panel of antibodies would, in principle, permit 'immunological' mapping of dystrophin mutations. This is diagnostically important in the 35% of families where no mutation is detectable at the DNA level. Secondly, by using this mapping technique it may also become possible to identify the at risk haplotype when DNA analysis is not informative. This may be of great value in DMD carrier detection.

Deletion screening and prenatal diagnosis of Duchenne muscular dystrophy using cDNA probes Cf 23a and Cf 56a

We have screened patients of 14 families at risk for Duchenne muscular dystrophy (DMD) from the northern part of the German Democratic Republic using the cDNA clones Cf 23a and CF 56a. Of the 14 unrelated DMD families, 7 (50%) showed different deletions with these cDNA probes. A prenatal diagnosis by chorionic villi sampling was performed in a DMD family with patients showing a deletion of the 5.4 kb Pst I band detected by the cDNA probe Cf 56a. This band corresponds to a 10 kb exon region of the cDNA probe 8 of Koenig et al. The patient's mother was informative only for the flanking marker 99.6. The male fetus showed the same haplotype and the same deletion as the two patients.

Prenatal diagnosis of Duchenne muscular dystrophy: A three‐year experience in a rapidly evolving field

Application of molecular genetic techniques has greatly increased diagnostic possibilities of hereditary disorders. In 1983 the first linkage of Duchenne muscular dystrophy with flanking DNA probes was described, which made carrier detection possible in a limited number of cases. The first published prenatal diagnosis for Duchenne muscular dystrophy dates from 1985. DNA-analysis for Duchenne muscular dystrophy and Becker muscular dystrophy has become increasingly informative, firstly by the development of more flanking markers, followed by intragenic probes detecting deletions and, more recently, by the use of cDNA probes detecting a deletion or duplication mutation in over 60% of the Duchenne and Becker muscular dystrophy patients. Although these developments allow a highly reliable (greater than 99%) carrier detection and prenatal diagnosis in over 90% of cases, the continuing introduction of new probes and/or technologies has necessitated constant reappraisal of many families to derive maximum information. During the past 3 years we applied prenatal diagnosis for Duchenne and Becker muscular dystrophies with DNA-analysis on 53 male fetuses in 47 families. Twenty-two healthy male babies were born, after being diagnosed to have a low Duchenne muscular dystrophy risk. Two pregnancies also diagnosed as low risk have not yet come to term. In the other cases a high risk for Duchenne muscular dystrophy was found and the parents chose abortion. Our studies also revealed a number of important diagnostic pitfalls, such as non-paternity, karyotypic anomalies and gonadal mosaicism.

Prenatal diagnosis and carrier detection of Duchenne muscular dystrophy by restriction fragment length polymorphism analysis with pERT 87 deoxyribonucleic acid probes

New methods of prenatal diagnosis based on recombinant deoxyribonucleic acid techniques are assuming increased importance in obstetrics practice. Carrier detection and prenatal diagnosis of Duchenne muscular dystrophy were performed with the use of three intragenic probes and four restriction enzymes to test six polymorphic sites. Twenty-seven families at risk for Duchenne muscular dystrophy were studied. Eleven at-risk pregnancies were studied; two affected males and four carrier females were predicted. Some families with a single affected individual were shown to have had a spontaneous mutation and were therefore at a much lower risk in future pregnancies.

Impact of first-trimester chromosome, DNA, and metabolic studies on pregnancies at high genetic risk: experience with 1,000 cases.

We describe the results and follow-up of chorionic villus studies in 1,034 pregnancies at risk for chromosome or metabolic disorders. Direct chromosome studies were successful in 99.7% and yielded results within a few days. Fifty pregnancies at risk for an unbalanced translocation, inherited from parents with many small reciprocal translocations, were a good test for the quality of the direct method. The 101 metabolic studies involving 28 disorders were correct in 99 pregnancies in the first trimester. In two cases a correct diagnosis was obtained by the confirmatory amniocentesis. DNA studies were carried out in pregnancies of male fetuses at risk for Duchenne muscular dystrophy and a few metabolic disorders. The abortion rate after chorionic villus sampling was 5.1% but more than half of the pregnant women were greater than or equal to 36 years old and have a spontaneous abortion rate of 10% between the 10th and 14th week according to Gustavii [Lancet 1:562, 1984]. Follow-up studies confirmed results of all chromosome studies after termination when there was fetal cell growth; the outcome of 504 consecutive continuing pregnancies showed no discrepancies of the phenotype after birth. It was concluded that first-trimester chorionic villi studies gave reliable results and were increasingly preferred by the patients, while the sampling can be considered a safe procedure based on the currently available data.

Creatine-kinase and pyruvate-kinase activities in normal children: implications in Duchenne muscular dystrophy carrier detection.

Serum creatine-kinase (CK) and pyruvate-kinase (PK) levels were determined in 201 boys and girls less than 15 years old to establish values and to investigate a possible correlation between enzyme activity, sex, and age. It was observed that the mean CK activity in boys was significantly higher than in females (of all ages), whereas it did not differ statistically between girls and women. A slight but significant correlation between CK activity and age was found only in females. The mean PK activity in children was significantly greater than in adult women and it decreased significantly with age in children of both sexes. Furthermore, a slight correlation between CK and PK was observed only in girls. Based on these results, we suggest that the results of CK and PK determinations of females at risk for Duchenne muscular dystrophy should be compared with controls of comparable age and sex.

Isolation of probes detecting restriction fragment length polymorphisms from X chromosome-specific libraries: potential use for diagnosis of Duchenne muscular dystrophy.

We have isolated 23 human X chromosome-specific DNA fragments from lambda libraries, prepared from flow-sorted X chromosomes. To increase diagnostic potential for X-linked genetic disorders, including Duchenne muscular dystrophy (DMD), the fragments were tested for restriction fragment length polymorphisms (RFLPs) with six restriction enzymes. All fragments were regionally mapped to segments of the X chromosome with a panel of somatic cell hybrids and with human cell lines carrying unbalanced chromosomal abnormalities. Two of the isolated probes detected a high frequency RFLP. One, 754, maps between Xp11.3 and Xp21 and detects a PstI polymorphism with an allele frequency of 0.38. The other, 782, maps between Xp22.2 and Xp22.3 and reveals an EcoRI polymorphism with an allele frequency of 0.40. According to a pilot linkage study of families at risk for Duchenne muscular dystrophy, 754 gives a maximum Lod score of 7.6 at a recombination fraction of 0.03. Probe 782 lies telomeric to DMD with a maximum Lod score of 2.2 at a recombination fraction of 0.17. Using our X-chromosomal probes and a set of autosomal probes, isolated and examined in an identical way, we found a significantly lower RFLP frequency for the X chromosome as compared to the autosomes.

Plasma creatine kinase and myoglobin levels, before and after abortion, in human fetuses at risk for Duchenne muscular dystrophy.

Plasma levels of creatine kinase (CK) were measured in 14 abortuses, nine of which were at risk for Duchenne muscular dystrophy (DMD). The plasma CK level was found to be increased in all abortuses, compared with the value obtained by fetoscopy before the termination. The causes of the increase in CK level were found to be 1) method of termination, 2) physical state of the abortus at delivery, 3) delay between delivery of the abortus and taking the blood sample, and 4) site of blood sampling. It is concluded that even under optimum conditions of termination the plasma creatine kinase level of the abortus is significantly raised above the true level; hence, this measurement is not reliable as a guide to the genetic status of the fetus. Cardiac leakage was the main source of the raised plasma CK level in the abortus and this was corroborated by measurement of myoglobin levels.

The foetus in Duchenne muscular dystrophy: muscle growth in tissue culture.

In tissue culture of muscle from five normal foetuses and four male foetuses at risk for Duchenne muscular dystrophy, no differences were found with regard to the ease with which cultures could be established and maintained, or in gross morphology or rate of growth and differentiation in culture. Yet before culture, muscle histology was clearly abnormal in at least one of the at-risk foetuses. The identification of the particular conditions of culture which prevent the full expression of the dystrophic process might be profitably pursued as a possible first step to finding a treatment.

Muscle histology and creatine kinase levels in the foetus in Duchenne muscular dystrophy.

X-LINKED Duchenne muscular dystrophy is a serious genetic disorder for which at present there is no effective treatment. It is characterised by progressive muscle wasting and weakness which first becomes apparent around the age of 3–5 years, leading to death usually before the age of 20 (ref. 1). A proportion of female heterozygous carriers have significantly elevated serum levels of creatine kinase and a woman who is found to be at high risk of having an affected son can elect to have amniocentesis with antenatal foetal sexing and selective abortion of any male foetus. A proportion of such aborted foetuses will, however, be normal but since the cause of the disorder is not known it is not yet possible to diagnose an affected male foetus in utero. As a first step in this direction we have examined the muscle histology and levels of creatine kinase in serum, muscle and amniotic fluid in a number of therapeutically aborted male foetuses at risk for Duchenne muscular dystrophy. We report that muscle histology, and possibly the serum level of creatine kinase, may be abnormal in this disorder even by the second trimester of pregnancy.

Muscle nuclear changes in fetuses at risk for Duchenne muscular dystrophy.

Muscle nuclear size was found to be significantly greater in fetuses at risk for Duchenne muscular dystrophy than in normal male fetuses of comparable gestational age. This supports the contention that the disease is already manifest in utero by the second trimester of pregnancy.

Muscle histology in fetuses at risk for Duchenne muscular dystrophy.

Quadriceps muscle samples taken from four therapeutically aborted male fetuses (16 to 21 weeks gestation) at risk of developing Duchenne muscular dystrophy have been examined histologically. Two of the four samples were indistinguishable from normal fetal muscle of comparable gestation. A slight increase in variability of fibre size and in mean fibre diameter was found in the third fetus. The fourth fetus, of 16 weeks gestation, showed a marked increase in variability of fibre size and in mean fibre diameter. There was also a significant number of hyaline fibres present. These changes are so similar to those reported in early pre‐clinical Duchenne muscular dystrophy, that it is suggested they represent the earliest histological signs of the disorder which is already manifest in utero.