The difficult path to diagnosis of the patient with spinal muscular atrophy. / El difícil camino al diagnóstico del paciente con atrofia muscular espinal.

Introduction. News treatments, make early diagnosis of spinal muscular atrophy (SMA) critical. The objective of this study is to analyze the different factors that influence delay in diagnosis. Population and methods. Patients with a molecular diagnosis of types I, II, and III SMA were included. Several parameters were studied, such as age at onset of first sign, what sign it was, and the time from recognition of first sign to confirmed diagnosis. Neurologists specialized in SMA conducted interviews, supported by the review of medical records when deemed necessary. Results. A total of 112 patients were interviewed. SMA I n = 40, SMA II n = 48, SMA III n = 24. The median age in months at the time of reporting the first sign was SMA I: 1.5 (R: 0-7), SMA II: 9 (R: 2-20), SMA III: 18 (R: 8-180). In all subtypes, first signs were identified by parents from 75% to 85% of the times. The median time from first sign to first medical consultation was less than a month in all 3 types. The median time in months, from first sign to confirmed molecular diagnosis in SMA I was: 2 (R: 0-11), in SMA II: 10 (R: 3-46), in SMA III: 31.5 (R: 4-288). Conclusions. There is a significant delay in SMA diagnosis mainly related to the absence of clinical suspicion. The delay is shorter in SMA I and longer in SMA III. Other factors include deficiencies in the health care system.

Introducción. Con las nuevas terapias, el diagnóstico temprano de la atrofia muscular espinal (AME) es esencial. El objetivo de este estudio es analizar los distintos componentes que influyen en el retraso diagnóstico. Población y métodos. Se incluyeron pacientes con un diagnóstico molecular de AME tipo I, II y III. Se estudiaron varios parámetros, como la edad al momento de la aparición del primer signo, qué signo fue y el intervalo entre este y el diagnóstico confirmado. Neurólogos especialistas realizaron entrevistas que se complementaron con la revisión de historias clínicas cuando fue necesario. Resultados. Se entrevistaron 112 pacientes. AME I n = 40, AME II n = 48, AME III n = 24. La mediana de edad en meses al momento del reporte del primer signo fue AME I: 1,5 (R 0-7), AME II: 9 (R 2-20), AME III: 18 (R 8-180). Los primeros signos fueron reconocidos por los padres en el 75 % al 85 % de las veces en todos los subtipos. La mediana del tiempo transcurrido entre el primer signo y la primera consulta médica fue menor a un mes en los tres tipos. La mediana de tiempo transcurrido en meses entre el primer signo y el diagnóstico molecular confirmado fue en AME I: 2 (R 0-11), en AME II: 10 (346) y en AME III: 31,5 (R 4-288). Conclusiones. Existe un significativo retraso en el diagnóstico de la AME relacionado fundamentalmente a la falta de sospecha clínica. La demora es menor en AME I y mayor en AME III. Otros factores incluyen deficiencias en el sistema de salud.

Theragnosis for Duchenne Muscular Dystrophy.

Dystrophinopathies cover a spectrum of rare progressive X-linked muscle diseases, arising from DMD mutations. They are among the most common pediatric muscular dystrophies, being Duchenne muscular dystrophy (DMD) the most severe form. Despite the fact that there is still no cure for these serious diseases, unprecedented advances are being made for the development of therapies for DMD. Some of which are already conditionally approved: exon skipping and premature stop codon read-through. The present work aimed to characterize the mutational spectrum of DMD in an Argentinian cohort, to identify candidates for available pharmacogenetic treatments and finally, to conduct a comparative analysis of the Latin American (LA) frequencies of mutations amenable for available DMD therapies. We studied 400 patients with clinical diagnosis of dystrophinopathy, implementing a diagnostic molecular algorithm including: MLPA/PCR/Sanger/Exome and bioinformatics. We also performed a meta-analysis of LA's metrics for DMD available therapies. The employed algorithm resulted effective for the achievement of differential diagnosis, reaching a detection rate of 97%. Because of this, corticosteroid treatment was correctly indicated and validated in 371 patients with genetic confirmation of dystrophinopathy. Also, 20 were eligible for exon skipping of exon 51, 21 for exon 53, 12 for exon 45 and another 70 for premature stop codon read-through therapy. We determined that 87.5% of DMD patients will restore the reading frame with the skipping of only one exon. Regarding nonsense variants, UGA turned out to be the most frequent premature stop codon observed (47%). According to the meta-analysis, only four LA countries (Argentina, Brazil, Colombia and Mexico) provide the complete molecular algorithm for dystrophinopathies. We observed different relations among the available targets for exon skipping in the analyzed populations, but a more even proportion of nonsense variants (∼40%). In conclusion, this manuscript describes the theragnosis carried out in Argentinian dystrophinopathy patients. The implemented molecular algorithm proved to be efficient for the achievement of differential diagnosis, which plays a crucial role in patient management, determination of the standard of care and genetic counseling. Finally, this work contributes with the international efforts to characterize the frequencies and variants in LA, pillars of drug development and theragnosis.

El difícil camino al diagnóstico del paciente con atrofia muscular espinal / The difficult path to diagnosis of the patient with spinal muscular atrophy

Introducción. Con las nuevas terapias, el diagnóstico temprano de la atrofia muscular espinal (AME) es esencial. El objetivo de este estudio es analizar los distintos componentes que influyen en el retraso diagnóstico. Población y métodos. Se incluyeron pacientes con un diagnóstico molecular de AME tipo I, II y III. Se estudiaron varios parámetros, como la edad al momento de la aparición del primer signo, qué signo fue y el intervalo entre este y el diagnóstico confirmado. Neurólogos especialistas realizaron entrevistas que se complementaron con la revisión de historias clínicas cuando fue necesario. Resultados. Se entrevistaron 112 pacientes. AME I n = 40, AME II n = 48, AME III n = 24. La mediana de edad en meses al momento del reporte del primer signo fue AME I: 1,5 (R 0-7), AME II: 9 (R 2-20), AME III: 18 (R 8-180). Los primeros signos fueron reconocidos por los padres en el 75 % al 85 % de las veces en todos los subtipos. La mediana del tiempo transcurrido entre el primer signo y la primera consulta médica fue menor a un mes en los tres tipos. La mediana de tiempo transcurrido en meses entre el primer signo y el diagnóstico molecular confirmado fue en AME I: 2 (R 0-11), en AME II: 10 (3-46) y en AME III: 31,5 (R 4-288). Conclusiones. Existe un significativo retraso en el diagnóstico de la AME relacionado fundamentalmente a la falta de sospecha clínica. La demora es menor en AME I y mayor en AME III. Otros factores incluyen deficiencias en el sistema de salud.

Introduction. News treatments, make early diagnosis of spinal muscular atrophy (SMA) critical. The objective of this study is to analyze the different factors that influence delay in diagnosis. Population and methods. Patients with a molecular diagnosis of types I, II, and III SMA were included. Several parameters were studied, such as age at onset of first sign, what sign it was, and the time from recognition of first sign to confirmed diagnosis. Neurologists specialized in SMA conducted interviews, supported by the review of medical records when deemed necessary. Results. A total of 112 patients were interviewed. SMA I n = 40, SMA II n = 48, SMA III n = 24. The median age in months at the time of reporting the first sign was SMA I: 1.5 (R: 0­7), SMA II: 9 (R: 2­20), SMA III: 18 (R: 8­180). In all subtypes, first signs were identified by parents from 75% to 85% of the times. The median time from first sign to first medical consultation was less than a month in all 3 types. The median time in months, from first sign to confirmed molecular diagnosis in SMA I was: 2 (R: 0­11), in SMA II: 10 (R: 3­46), in SMA III: 31.5 (R: 4­288). Conclusions. There is a significant delay in SMA diagnosis mainly related to the absence of clinical suspicion. The delay is shorter in SMA I and longer in SMA III. Other factors include deficiencies in the health care system.

Nutritional assessment of patients with neuromuscular diseases.

OBJECTIVE: To study the nutritional status of patients with Duchenne muscular dystrophy and amyotrophic lateral sclerosis. DESIGN: A total of 34 Duchenne muscular dystrophy and seven amyotrophic lateral sclerosis patients were studied. Body mass index, patient's body weight for zero muscle mass as a percentage of the theoretical weight for zero muscle mass, and creatinine-height index were calculated. RESULTS: Substantial differences were found between body mass index and percentage of expected weight for zero muscle mass. No amyotrophic lateral sclerosis patients were classified as overweight by body mass index, whereas five were overweight by the percentage of expected weight for zero muscle mass method. Five Duchenne muscular dystrophy patients were classified as overweight by body mass index, and 30 were overweight by the percentage of expected weight for zero muscle mass. According to the creatinine-height index, no patient with amyotrophic lateral sclerosis or Duchenne muscular dystrophy showed normal body muscle mass. No correlation was found between creatinine-height index, percentage of expected weight for zero muscle mass, and body mass index. CONCLUSIONS: The body mass index should be used with caution for the evaluation of the nutritional status of patients with amyotrophic lateral sclerosis and Duchenne muscular dystrophy. Indices that incorporate the assessment of the compartmental distribution of muscle and fat are more sensitive.

Peak flow and peak cough flow in the evaluation of expiratory muscle weakness and bulbar impairment in patients with neuromuscular disease.

OBJECTIVE: To study the expiratory muscle force and the ability to cough estimated by the peak expiratory flow and peak cough flow in patients with Duchenne muscular dystrophy and amyotrophic lateral sclerosis. DESIGN: A total of 27 patients with amyotrophic lateral sclerosis and 52 patients with Duchenne muscular dystrophy were studied. From the group of 144 normal subjects of this laboratory, we selected 38 for comparison. RESULTS: The maximal inspiratory pressure in patients with Duchenne muscular dystrophy and amyotrophic lateral sclerosis was 64.5 +/- 24.7% and 37.8 +/- 21.8%, respectively, and maximal expiratory pressure was 64.2 +/- 32.5% and 37.7 +/- 21.6%, respectively. Patient groups showed a significant lower peak expiratory flow than normal subjects. Higher peak cough flow than peak expiratory flow was found in all groups. The peak cough flow-peak expiratory flow difference was 46 +/- 18% in normal subjects, 43 +/- 23% in patients with Duchenne muscular dystrophy, and 11 +/- 17% in patients with amyotrophic lateral sclerosis. The peak expiratory flow and peak cough flow were not different in bulbar onset amyotrophic lateral sclerosis. In patient groups, the dynamic and static behavior correlated positively. CONCLUSIONS: These results suggest that peak cough flow-peak expiratory flow is useful to monitor expiratory muscle weakness and bulbar involvement and to assess its evolution in these patients.