Clinical and genetic characteristics of female dystrophinopathy carriers

Exertion induced rhabdomyolysis in both triceps muscles in a 36-year old woman: A case report

Rhabdomyolysis is a condition, often caused by strenuous exercise, which can lead to acute kidney injury, severe electrolyte imbalances, coagulopathies, compartment syndromes, and even have a fatal outcome in a few cases. Recognition and management of fluid and electrolyte abnormalities is one of the first steps of treatment and key to a good outcome. We report a case of a 36-year old woman who was referred to the ER by her general practitioner with severe muscle tenderness to the upper arms and highly elevated creatine kinase (CK) serum levels. Initial ultrasound imagery showed a patent venous system but demonstrated a moderate edematous infiltration of the muscle bellies of both m. triceps. Additional magnetic resonance imagery showed a hyperintense signal in T2 in both triceps' muscles. Given the clinical presentation, the MRI-findings were consistent with a form of exertion-induced rhabdomyolysis of both triceps' muscles. The patient was admitted for administration of IV-fluids to prevent acute kidney injury. Symptoms resolved in a few days and new magnetic resonance imagery showed a regression of the subcutaneous soft tissue infiltration. The aim of this paper is to raise awareness about this diagnosis. If overlooked, severe complications as mentioned above can occur.

Genetic counseling for the dystrophinopathies-Practice resource of the National Society of Genetic Counselors

The dystrophinopathies encompass the phenotypically variable forms of muscular dystrophy caused by pathogenic variants in the DMD gene. The dystrophinopathies include the most common inherited muscular dystrophy among 46,XY individuals, Duchenne muscular dystrophy, as well as Becker muscular dystrophy and other less common phenotypic variants. With increased access to and utilization of genetic testing in the diagnostic and carrier setting, genetic counselors and clinicians in diverse specialty areas may care for individuals with and carriers of dystrophinopathy. This practice resource was developed as a tool for genetic counselors and other health care professionals to support counseling regarding dystrophinopathies, including diagnosis, health risks and management, psychosocial needs, reproductive options, clinical trials, and treatment. Genetic testing efforts have enabled genotype/phenotype correlation in the dystrophinopathies, but have also revealed unexpected findings, further complicating genetic counseling for this group of conditions. Additionally, the therapeutic landscape for dystrophinopathies has dramatically changed with several FDA-approved therapeutics, an expansive research pathway, and numerous clinical trials. Genotype-phenotype correlations are especially complex and genetic counselors' unique skill sets are useful in exploring and explaining this to families. Given the recent advances in diagnostic testing and therapeutics related to dystrophinopathies, this practice resource is a timely update for genetic counselors and other healthcare professionals involved in the diagnosis and care of individuals with dystrophinopathies.

Treatment with ataluren in four symptomatic Duchenne carriers. A pilot study

Duchenne muscular dystrophy (DMD) is a devastating X-linked neuromuscular disorder caused by dystrophin gene deletions (75%), duplications (15-20%) and point mutations (5-10%), a small portion of which are nonsense mutations. Women carrying dystrophin gene mutations are commonly unaffected because the wild X allele may produce a sufficient amount of the dystrophin protein. However, approximately 8-10% of them may experience muscle symptoms and 50% of those over 40 years develop cardiomyopathy. The presence of symptoms defines the individual as an affected "symptomatic or manifesting carrier". Though there is no effective cure for DMD, therapies are available to slow the decline of muscle strength and delay the onset and progression of cardiac and respiratory impairment. These include ataluren for patients with nonsense mutations, and antisense oligonucleotides therapies, for patients with specific deletions. Symptomatic DMD female carriers are not included in these indications and little data documenting their management, often entrusted to the discretion of individual doctors, is present in the literature. In this article, we report the clinical and instrumental outcomes of four symptomatic DMD carriers, aged between 26 and 45 years, who were treated with ataluren for 21 to 73 months (average 47.3), and annually evaluated for muscle strength, respiratory and cardiological function. Two patients retain independent ambulation at ages 33 and 45, respectively. None of them developed respiratory involvement or cardiomyopathy. No clinical adverse effects or relevant abnormalities in routine laboratory values, were observed.

Cognitive function in DMD carriers: personal case series and literature review

Improvement in clinical conditions allowed physicians to pay more attention to the cognitive function in DMD patients, leading to description of a cognitive impairment not only in affected males, but in female carriers as well. This study aimed to investigate the cognitive involvement in a cohort of DMD carriers and to summarize the current knowledge about the intellectual involvement and neuropsychological profile in DMD/BMD carriers. Our case series consisted of 22 carrier patients from two different centers (IRCCS Mondino, Pavia and Policlinico Gemelli, Rome), for whom we retrospectively collected cognitive, clinical and genetic data. For literature review, we selected 9 studies published in English language from 2011 to 2023 and cited in PubMed. We found that the average IQ of DMD carriers was lower (74; very low) than the average score on normal curve (100 as average standard score). Furthermore, about 50% of them fell in the "extremely low IQ" range, compared with 2-3% of general population. A higher incidence of intellectual disability was confirmed in symptomatic DMD carriers (mean IQ 66; extremely low) from IRCCS Mondino, but not in the asymptomatic ones (mean IQ 99; average), when compared to the general population. Current literature, albeit limited, seems to confirm the presence of a cognitive impairment in carriers, although milder than in affected males but with a similar neuropsychological profile. However, further studies are necessary to delve deeper into this issue and provide adequate educational support.

Newborn Screening for Duchenne Muscular Dystrophy: First Year Results of a Population-Based Pilot

Advancements in therapies for Duchenne muscular dystrophy (DMD) have made diagnosis within the newborn period a high priority. We undertook a consortia approach to advance DMD newborn screening in the United States. This manuscript describes the formation of the Duchenne Newborn Screening Consortium, the development of the pilot protocols, data collection tools including parent surveys, and findings from the first year of a two-year pilot. The DMD pilot design is population-based recruitment of infants born in New York State. Data tools were developed to document the analytical and clinical validity of DMD NBS, capture parental attitudes, and collect longitudinal health information for diagnosed newborns. Data visualizations were updated monthly to inform the consortium on enrollment. After 12 months, 15,754 newborns were screened for DMD by the New York State Newborn Screening (NYS NBS) Program. One hundred and forty screened infants had borderline screening results, and sixteen infants were referred for molecular testing. Three male infants were diagnosed with dystrophinopathy. Data from the first year of a two-year NBS pilot for DMD demonstrate the feasibility of NBS for DMD. The consortia approach was found to be a useful model, and the Newborn Screening Translational Research Network's data tools played a key role in describing the NBS pilot findings and engaging stakeholders.

Newborn screening for Duchenne muscular dystrophy-early detection and diagnostic algorithm for female carriers of Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is the most common pediatric-onset form of muscular dystrophy, occurring in 1 in 5,000 live male births. DMD is a multi-system disease resulting in muscle weakness with progressive deterioration of skeletal, heart, and smooth muscle, and learning disabilities. Pathogenic/likely pathogenic (P/LP) variants in the DMD gene, which encodes dystrophin protein, cause dystrophinopathy. All males with a P/LP variant in the X-linked DMD gene are expected to be affected. Two to 20% of female heterozygotes with a P/LP variant develop symptoms of dystrophinopathy ranging from mild muscle weakness to significant disability similar to Becker muscular dystrophy. Recently, with improvements in therapies and testing methodology, there is stronger evidence supporting newborn screening (NBS) for DMD for males and females because females may also develop symptoms. A consented pilot study to screen newborns for DMD was initiated in New York State (NYS) and conducted from 2019 to 2021. The identification of female carriers and the realization of the subsequent uncertainty of providers concerning follow-up during the pilot led to the development of algorithms for screening and diagnosis of carrier females, including both NBS and cascade molecular testing of family members.

A Decade of Progress in Gene Targeted Therapeutic Strategies in Duchenne Muscular Dystrophy: A Systematic Review

As one of the most severe forms of muscle dystrophy, Duchenne muscular dystrophy (DMD) results in progressive muscle wasting, ultimately resulting in premature death due to cardiomyopathy. In the many years of research, the solution to DMD remains palliative. Although numerous studies including clinical trials have provided promising results, approved drugs, even, the therapeutic window is still minimal with many shortcomings to be addressed. Logically, to combat DMD that arose from a single genetic mutation with gene therapy made sense. However, gene-based strategies as a treatment option are no stranger to drawbacks and limitations such as the size of the dystrophin gene and possibilities of vectors to elicit immune responses. In this systematic review, we aim to provide a comprehensive compilation on gene-based therapeutic strategies and critically evaluate the approaches relative to its efficacy and feasibility while addressing their current limitations. With the keywords “DMD AND Gene OR Genetic AND Therapy OR Treatment,” we reviewed papers published in Science Direct, PubMed, and ProQuest over the past decade (2012–2021).

Can symptomatic nmDuchenne carriers benefit from treatment with ataluren? Results of 193-month follow-up

Duchenne's muscular dystrophy (DMD) is an X-linked neuromuscular disorder caused by deletions (75%), duplications (15-20%) and point mutations (5-10%) in the dystrophin gene. Among the latter, stop-codon point mutations are rare. Female carriers of dystrophin gene mutations are usually asymptomatic as they are "protected" by the second X-chromosome, which produces a normal dystrophin protein. However, about 8-10% of them can present symptoms that set the clinical picture of the manifesting or symptomatic carrier. Although no causative cure there is for DMD, therapies are available to slow the decline of muscle weakness and delay the onset of heart and respiratory involvement. However, there is limited data in the literature documenting the treatment of symptomatic carriers, often entrusted to the sensitivity of individual doctors. In this paper, we report the follow-up outcomes of four European symptomatic nmDMD carriers treated with ataluren, overall followed for 193 months. Annual assessment of muscle strength, pulmonary lung function tests, and echocardiography, indicate a mild attenuation of disease progression under treatment.. There were no adverse clinical effects or relevant abnormalities in routine laboratory tests. We can conclude that ataluren appears to stabilize, if not slightly improve, the clinical course of patients with a good safety profile, especially if we consider that the treatment was late for 3/4 patients, at a mean age of 36.6 ± 10.6 years.

miRNome profiling in Duchenne muscular dystrophy; identification of asymptomatic and manifesting female carriers

Duchenne muscular dystrophy (DMD) is a fatal neuromuscular disorder that occurs due to inactivating mutations in DMD gene, leading to muscular dystrophy. Prediction of pathological complications of DMD and the identification of female carriers are important research points that aim to reduce disease burden. Herein, we describe a case of a late DMD patient and his immediate female family members, who all carry same DMD mutation and exhibited varied degrees of symptoms. In our study, we sequenced the whole miRNome in leukocytes and plasma of the family members and results were validated using real-time PCR. Our results highlighted the role of miR-409-3p, miR-424-5p, miR-144-3p as microRNAs that show correlation with the extent of severity of muscular weakness and can be used for detection of asymptomatic carriers. Cellular and circulating levels of miR-494-3p had shown significant increase in symptomatic carriers, which may indicate significant roles played by this miRNA in the onset of muscular weakness. Interestingly, circulating levels of miR-206 and miR-410-3p were significantly increased only in the severely symptomatic carrier. In conclusion, our study highlighted several miRNA species, which could be used in predicting the onset of muscle and/or neurological complications in DMD carriers.

Recurrent Exercise-Induced Rhabdomyolysis in a Healthy Adolescent Girl

Female symptomatic carriers of Duchenne muscular dystrophy (DMD) are uncommon findings. Much of this disease has been studied from a male perspective, but female disease presentation and progression are rarely described. This report describes a female adolescent patient with a rare and unconventional presentation of DMD.

Prenatal diagnosis of Duchenne muscular dystrophy revealed a novel mosaic mutation in Dystrophin gene: a case report

BACKGROUND

Duchenne muscular dystrophies (DMDs) are X-linked recessive neuromuscular disorders with malfunction or absence of the Dystrophin protein. Precise genetic diagnosis is critical for proper planning of patient care and treatment. In this study, we described a Chinese family with mosaic DMD mutations and discussed the best method for prenatal diagnosis and genetic counseling of X-linked familial disorders.

METHODS

We investigated all variants of the whole dystrophin gene using multiple DNA samples isolated from the affected family and identified two variants of the DMD gene in a sick boy and two female carriers by targeted next generation sequencing (TNGS), Sanger sequencing, and haplotype analysis.

RESULTS

We identified the hemizygous mutation c.6794delG (p.G2265Efs*6) of DMD in the sick boy, which was inherited from his mother. Unexpectedly, a novel heterozygous mutation c.6796delA (p.I2266Ffs*5) of the same gene, which was considered to be a de novo variant, was detected from his younger sister instead of his mother by Sanger sequencing. However, further NGS analysis of the mother and her amniotic fluid samples revealed that the mother carried a low-level mosaic c.6796delA mutation.

CONCLUSIONS

We reported two different mutations of the DMD gene in two siblings, including the novel mutation c.6796delA (p.I2266Ffs*5) inherited from the asymptomatic mosaic-carrier mother. This finding has enriched the knowledge of the pathogenesis of DMD. If no mutation is detected in obligate carriers, the administration of intricate STR/NGS/Sanger analysis will provide new ideas on the prenatal diagnosis of DMD.

Serum MyomiRs as Biomarkers for Female Carriers of Duchenne/Becker Muscular Dystrophy

Background: Duchenne/Becker muscular dystrophy (DMD/BMD) is an X-linked recessive lethal neuromuscular disease. MicroRNAs expressed in striated muscle, myomiRs, have been proposed as its potential biomarkers. Serum creatine kinase (CK) is commonly used as a biomarker in clinical practice, but it is not reliable. The aim of this study was to assess whether serum levels of myomiRs has diagnostic value for detection of female DMD/BMD carriers with normal or elevated CK.

Methods: Thirty four female carriers and 33 age-matched healthy female controls were enrolled. Peripheral blood samples were collected and serum miRNAs were extracted for measurement of miR-1, miR-133a, miR-133b, miR-206, miR-208a, miR-208b, and miR-499 by quantitative real-time polymerase chain reaction.

Results: MiR-1, miR-133a, miR-133b, miR-206, miR-208a, miR-208b, and miR-499 were upregulated in all female carriers in comparison to healthy controls. MiR-1 (Spearman's rho = +0.406, p = 0.017) was correlated with CK in the female carrier group. Receiver operating characteristic curve analysis of all seven myomiRs showed that the area under the curve (AUC) for miR-499, miR-133b, miR-1, miR-208b, and miR-133a exceeded 70.0%, and for miR-206 and miR-208a exceeded 60.0%. MiR-133b and miR-499 were significantly increased in all female carriers, even those with normal CK. AUC for the combination of all seven miRNAs was 87.2%. CK (OR 0.406, 95% CI 0.000–0.001, p < 0.0001) and miR-499 (OR 0.323, 95% CI 0.023–0.106, p = 0.003) were considered to be independent predictors for female carriers presence in the multivariable regression analysis model.

Conclusions: MiR-133b and miR-499 are potentially useful biomarkers for female carriers with DMD/BMD (including those with normal CK). The combination of all seven serum miRNAs and their respective combinations with CK have better diagnostic value for female carriers than either CK or any separate miRNA.

Mitochondrial Dysfunction Is an Early Consequence of Partial or Complete Dystrophin Loss in mdx Mice

Duchenne muscular dystrophy (DMD) is characterized by rapid wasting of skeletal muscle. Mitochondrial dysfunction is a well-known pathological feature of DMD. However, whether mitochondrial dysfunction occurs before muscle fiber damage in DMD pathology is not well known. Furthermore, the impact upon heterozygous female mdx carriers (mdx/+), who display dystrophin mosaicism, has received little attention. We hypothesized that dystrophin deletion leads to mitochondrial dysfunction, and that this may occur before myofiber necrosis. As a secondary complication to mitochondrial dysfunction, we also hypothesized metabolic abnormalities prior to the onset of muscle damage. In this study, we detected aberrant mitochondrial morphology, reduced cristae number, and large mitochondrial vacuoles from both male and female mdx mice prior to the onset of muscle damage. Furthermore, we systematically characterized mitochondria during disease progression starting before the onset of muscle damage, noting additional changes in mitochondrial DNA copy number and regulators of mitochondrial size. We further detected mild metabolic and mitochondrial impairments in female mdx carrier mice that were exacerbated with high-fat diet feeding. Lastly, inhibition of the strong autophagic program observed in adolescent mdx male mice via administration of the autophagy inhibitor leupeptin did not improve skeletal muscle pathology. These results are in line with previous data and suggest that before the onset of myofiber necrosis, mitochondrial and metabolic abnormalities are present within the mdx mouse.