Small mutations in Duchenne/Becker muscular dystrophy in 164 unrelated Polish patients.

In the 164 patients with Duchenne/Becker muscular dystrophy, we found 142 different small mutations including 51 novel mutations not listed in the LOVD, the UMD-DMD, the ClinVar, and the HGMD databases. Among all mutations, nonsense mutations occurred in 45.7%, frameshift mutations in 32.9%, and splicing mutations in 19.5%. Small mutations were distributed throughout the whole dystrophin gene. Splicing mutations were twice more common in BMD patients than in DMD patients. Eighty-two percent of mothers of the males affected with DMD/BMD were found to be carriers of small mutations.

Deletions, not duplications or small mutations, are the predominante new mutations in the dystrophin gene.

Examination of the carrier state was performed in 744 unrelated mothers of the Duchenne muscular dystrophy/Becker muscular dystrophy (DMD/BMD) probands with identified mutations in the dystrophin gene. Owing to that it was possible to assess frequency and type of new mutations in the gene. Contrary to the Japanese observations of Lee et al. published in this journal, we did not find significant differences in the carrier frequency between mothers of DMD and BMD patients. However, we found that new mutations in patients with deletions were significantly more frequent than in those with duplications and small mutations: of 564 unrelated patients with deletions, 236 (41.8%) carried new mutations, the respective values for duplications and small mutations were 21 of 95 patients (22.1%) and 18 of 85 patients (21.2%)-the differences highly significant (P<0.0001).

Prenatal diagnosis of Duchenne and Becker muscular dystrophies: Underestimated problem of the secondary prevention of monogenetic disorders.

AIM: The aim of this study was to analyze the influence of effective preconceptional testing for carrier status in women at risk for Duchenne and Becker muscular dystrophies (D/BMD) on the prenatal diagnosis. METHODS: A retrospective analysis of 201 prenatal tests was performed in 169 Polish women at risk, in regard to time of testing for carrier status (prior to conception or during pregnancy) and carrier status of tested women, including confirmed D/BMD carriers (n = 78; 46.2%), D/BMD non-carriers - tested for germline mosaicism risk (n = 23; 13.6%), and women at risk with uncertain carrier status (n = 68; 40.2%). RESULTS: Only 52.7% of women were tested for D/BMD carrier status prior to conception and in these women prenatal diagnosis was carried out more frequently in the first trimester of pregnancy (64.7% vs 47.8%; P = 0.035). The results of prenatal testing in male fetuses in pregnancies of confirmed D/BMD carriers and D/BMD non-carriers - tested for germline mosaicism risk were conclusive in all cases, whereas in women with uncertain carrier status, only 60.0% of results were conclusive. Eighty-five of 103 female fetuses (82.5%) were tested prenatally and in 31.8% of them fetal carrier status was confirmed. CONCLUSION: Carrier status testing in women prior to conception has a positive impact on the frequency of first-trimester prenatal diagnosis and known D/BMD carrier status on the effectiveness of prenatal diagnosis. Due to the low percentage of women tested effectively prior to conception, carrier status testing in the families at risk should be propagated (including possibility of prenatal diagnosis of female fetuses).

A rare subclinical or mild type of Becker muscular dystrophy caused by a single exon 48 deletion of the dystrophin gene.

In the material of 227 families with Becker muscular dystrophy (BMD), we found nine non-consanguineous families with 17 male individuals carrying a rare mutation-a single exon 48 deletion of the dystrophin gene-who were affected with a very mild or subclinical form of BMD. They were usually detected thanks to accidental findings of elevated serum creatine phosphokinase (sCPK). A thorough clinical analysis of the carriers, both children (12) and adults (5), revealed in some of them muscle hypotonia (10/17) and/or very mild muscle weakness (9/17), as well as decreased tendon reflexes (6/17). Adults, apart from very mild muscle weakness and calf hypertrophy in some, had no significant abnormalities on neurological assessments and had good exercise tolerance. Parents of the children carriers of the exon 48 deletion are usually unaware of their children being affected, and possibly at risk of developing life-threatening cardiomyopathy. The same concerns the adult male carriers. Therefore, the authors postulate undertaking preventive measures such as cascade screening of the relatives of the probands. Newborn screening programmes of Duchenne muscular dystrophy (DMD)/BMD based on sCPK marked increase may be considered.

First trimester pregnancy loss: Clinical implications of genetic testing.

Around 10-15% of pregnancies result in a spontaneous first trimester miscarriage, which is most frequently caused by chromosomal abnormalities, mainly aneuploidies. Genetic analysis of pregnancy loss includes conventional G-banding karyotyping and various molecular methods. Apart from variable methodological limitations, the effectiveness of genetic analysis depends on the type and quality of the tested sample. To improve the reliability of genetic testing, we present methods of appropriate collection and pre-laboratory preparation of chorionic villi from first trimester miscarriage. We also discuss issues of maternal cell contamination, placental mosaicism and reciprocal and Robertsonian translocations in the context of interpretation of the results and genetic counseling.

Biomarkers for risk stratification in secondary cardiovascular prevention. A role of red blood cell distribution width and calcium score.

BACKGROUND: Patients with coronary artery disease (CAD) are considered as high risk in terms of secondary cardiovascular prevention. However, obviously the risk is not homogenous across the whole group. Red blood cell distribution width (RDW) has been recently related to adverse outcomes in patients with atherosclerosis. Calcium score (CaS) may be used for risk stratification in primary prevention. The value of these biomarkers for prediction of cardiovascular outcomes in patients with CAD is unknown. METHODS: The study group comprised 269 consecutive patients with significant stable CAD. The primary endpoint was a composite of death or nonfatal myocardial infarction. RESULTS: Median post-discharge follow up was 43.2 months (IQR39.2-48.6). The primary outcome was observed in 27 patients including 13 deaths and 14 nonfatal myocardial infarction. According to ROC analysis the best cut-off value for RDW for prediction of the primary event was 14% [(AUC) = 0.69; 95%CI:0.63-0.75; p = 0.0002] and for CaS was 603 [(AUC) = 0.66; 95%CI:0.60-0.72; p = 0.001]. According to multivariable Cox regression analysis both RDW>14% (HR 2.6; 95%CI:1.1-5.9) and CaS>603 (HR 2.3; 95%CI:1.1-5.1) were independently correlated to the primary outcome. Subsequently, patients were categorized into three risk subgroups: LOW: CaS ≤ 603 and RDW ≤ 14-124(46.1%), MID: either CaS>603 or RDW>14-104(38.7%), and HIGH - CaS>603 and RDW>14-41(15.2%) patients. The respective risk of events according to Kaplan-Meier analysis were 4.03%, 9.62%, and 29.27% (p < 0.0001). CONCLUSIONS: RDW and calcium score may be predictors of future cardiovascular events in patients with significant CAD. They may be useful tools for risk stratification and may indicate patients suitable for more aggressive secondary prevention measures.