Distrofia miotónica congénita. Hallazgos clínicos, electrofisiológicos y genéticos de nuestra casuística / Congenital myotonic dystrophy. Clinical, electrophysiological and genetic findings of our casuistry

Introducción. La distrofia miotónica congénita es una enfermedad multisistémica de herencia autosómica dominante, heredada generalmente a través de la madre, y que se caracteriza porque al nacimiento, el recién nacido presenta hipotonía, problemas respiratorios y alimenticios, debilidad facial y general. Objetivos. Estudio descriptivo de nuestra experiencia en la distrofia miotónica congénita. Pacientes y métodos. Se estudiaron 12 pacientes con distrofiamiotónica congénita, pertenecientes a 9 familias donde las madres eran portadoras de la enfermedad, y se analizaron las características clínicas, electromiográficas y genéticas. Resultados. El retraso motor era manifiesto en todos los pacientes, así como el retraso intelectual, la disartria y la voz nasal. Los niños afectados presentaban más de 1.500 repeticiones del trinucleótido citosina-timina-guanina del cromosoma 19 determinadas por la técnica de Southern Blot. Las alteraciones electromiográficas de tipo miopático estaban presentes en todos ellos. La biopsia muscular realizada a 8 pacientes mostraba atrofia y predominio de fibras tipo 1 con núcleos centrales e hipertrofia de fibras tipo 2. Conclusión. Es necesario sospechar la distrofia miotónicaante casos de recién nacidos con hipotonía, en madres conhistoria de abortos o recién nacidos muertos. Una vez superados los primeros años de vida, su desarrollo es similar al dela distrofia miotónica del adulto. Es fundamental realizar el estudio genético a los afectados y portadores de esta enfermedad (AU)

Introduction. Congenital myotonic dystrophyis an autosomal dominant inherited generally transmitted multisystemic disease that is generally inherited through themother. It is characterized by the birth the newborn baby with hypotonia, respiratory and nutritional problems, and facial and general weakness. Objective. Descriptive study of our experience in congenital myotonic dystrophy. Patients and methods. Twelve patients with congenital myotonicdy strophy, belonging to 9 families in which the mother was a carrier of the disease have been studied. The clinical, electromyographic and genetic characteristics of their familieswere analyzed. Results. Motor retardation as well as the intellectual retardation,dysarthria and nasal voice was clear in all the patients.The affected children had more than 1,500 repetitions of the cytosine-thymine-guanine (CTG) trinucleotide on chromosome 19 determined by the Southern Blot technique. Myopathictype alterations were found in the electromyographsof all of the subjects. The muscular biopsy done in 8 patients showed atrophy and predominance of type 1 fibers with centralnuclei and type 2 fiber hypertrophy. Conclusion. Myotonic dystrophy should be suspected incases of newborn babies with hypotonia, in mothers with a back ground of abortions or stillborn babies. After surviving the first years of life, their development is similar to the myotonicdy strophy of the adult. It is fundamental to perform agenetic study in those who are affected by or carriers of the disease (AU)

[Bethanechol for neonatal transient gastrointestinal dismotility in two cases of congenital myotonic dystrophy].

Although gastrointestinal symptoms are frequently observed in congenital myotonic dystrophy (congenital MD) during early neonatal periods, there are few reports of gastrointestinal smooth muscle involvement and its management. We report two cases with congenital MD treated with bethanechol (0.25 mg/kg/dose 30 min before breast milk, 8 doses/day) for gastrointestinal dismotility. Two patients showed gastrointestinal symptoms characterized by increased gastric residua prior to the next feeding and gasless abdomen with relative gastric dilatation on abdominal X ray. Treatment with bethanechol resolved the gastrointestinal symptoms and allowed increase of daily feeding volume. We speculate that the main pathogenesis of transient gastrointestinal dismotility in neonates with congenital MD is gastroparesis probably due to "maturation arrest" of smooth muscle. Bethanechol may be one of the alternative prokinetic drugs to increase gastric emptying.

Congenital myotonic dystrophy: prenatal ultrasound findings and pregnancy outcome.

OBJECTIVE: The objective of this study was to assess the maternal and prenatal ultrasound findings and outcome in pregnancies complicated by congenital myotonic dystrophy Type 1 (DM1). METHODS: A retrospective chart review of all patients with a diagnosis of DM1 and pregnancy presenting to the Oxford Radcliffe Hospital between 1990 and 2004 was undertaken. Obstetric case notes were reviewed and details of all pregnancies obtained. This included data on prenatal diagnostic tests and obstetric ultrasound scans performed as well as pregnancy complications and pregnancy outcome. Maternal and fetal CTG expansion size was also recorded where available. Maternal genetic case notes were reviewed for details of maternal grip myotonia. RESULTS: Sixty pregnancies among 26 couples in which one of the parents was a carrier of DM1 were identified during the study period. These resulted in 36 (60%) pregnancies affected by congenital DM1 and 19 (31.7%) unaffected pregnancies. There were four miscarriages and one termination of pregnancy for non-medical reasons. Nineteen of the 36 affected pregnancies ended in termination following the antenatal diagnosis of congenital DM1 by either chorionic villus sampling (CVS) or amniocentesis. In the remaining 17 affected pregnancies (16 singleton and one twin) there was one miscarriage of an affected fetus with co-existing Down syndrome and eight perinatal deaths. The principal cause of perinatal death was respiratory failure in the early neonatal period. Antenatally noted clinical/sonographic abnormalities in these pregnancies included polyhydramnios (100%), talipes (26.6%) and borderline ventriculomegaly (13.3%). Uni- or bilateral talipes was noted at delivery in 10 of 16 (62.5%) neonates. Maternal grip myotonia was present in all but one of these cases. CONCLUSION: The antenatal findings of polyhydramnios and talipes should prompt a search for maternal grip myotonia. If present, definitive testing for congenital DM1 should be considered.

[A case of Möbius syndrome presenting with symptoms of severe infantile form of congenital muscular disorder].

Möbius syndrome is a rare disorder characterized by congenital bilateral facial nerve palsy. Abducent palsy or other cranial nerve palsy, facial malformations, limb malformations, and skeletal malformations are common features associated with this syndrome. We report a 9-month-old infant in whom congenital muscular disorder was previously suspected because of facial muscle involvement (mask-like face), respiratory and swallowing disturbances, and hypotonia since birth. After an improvement in the respiratory infection, she showed slightly exaggerated deep tendon reflexes and an improvement in muscle tone. The occurrence of combined facial nerve palsy, glossopharyngeal nerve palsy, vagus nerve palsy, and hypoglossal nerve palsy strongly suggested that she had Möbius syndrome. Finally, the absence of the roots of bilateral facial nerves on an MRI confirmed that the disorder was Möbius syndrome. We propose that a thin slice MRI should be obtained to observe the cranial nerves around the brain stem if patients show symptoms of congenital myopathy or congenital myotonic dystrophy as well as facial nerve and other cranial nerve paralyses.

[Congenital myotonic dystrophy--the significance of a handshake]. / Congenitale myotone dystrofie--wat is er 'aan de hand'?

Three neonates, all girls, were presented immediately after birth with severe hypotonia. Two of them needed artificial ventilation because of respiratory insufficiency. All three pregnancies had been complicated by reduced fetal movements and moderate cerebral ventricular dilatation and in two of the three there was also polyhydramnios and congenital talipes. In all three infants congenital myotonic dystrophy was suspected after diagnosing myotonia in the mother. This was done by observing that none of the mothers were unable to release their grip immediately on command after shaking hands. Ophthalmological examination of the women revealed polychromatic lens crystals characteristic of myotonic dystrophy. Congenital myotonic dystrophy was confirmed by DNA analysis, as well as myotonic dystrophy in the mothers. All had an expansion of the number of cytosine-thymine-guanine(CTG)-trinucleotides in a part of the myotonic dystrophy protein-kinase gene. The first two infants died after 2 days and 15 months respectively.

Brain MRI features of congenital- and adult-form myotonic dystrophy type 1: case-control study.

To compare and characterize the magnetic resonance imaging (MRI) of brain in the congenital and adult form of myotonic dystrophy type 1, we evaluated five patients with congenital dystrophy type 1, 10 age- and 10 disease duration-matched patients with adult-form dystrophy type 1 and 20 age-matched healthy volunteers. The ventricular enlargement was evaluated by the ventricular:brain ratio, the signal intensity of white matter posterosuperior to trigones by reference to standard images and the white matter lesions by a semiquantitative method. In the congenital dystrophy type 1, MRI was characterized by ventriculomegaly and moderate/severe hyperintensity of white matter posterosuperior to trigones, which showed no correlation with the age. MRI in the adult-form dystrophy type 1 was strictly related to disease duration and varied between normal findings, except for temporo-polar white matter lesions, in age-matched patients and ventriculomegaly with white matter hyperintensities in disease duration-matched patients. These results suggest that the origin of MRI abnormalities in myotonic dystrophy type 1 is mainly developmental for the congenital form and mainly degenerative for the adult form.

Paternal transmission of the congenital form of myotonic dystrophy type 1: a new case and review of the literature.

Myotonic dystrophy type 1 (DM1) is an autosomal dominant trinucleotide repeat disorder that shows anticipation. The mildest manifestations of the DM gene are usually noted in individuals with the smallest repeat sizes, while congenital myotonic dystrophy (CDM) is the most common clinical outcome of the larger expansions. For many years, it was thought that CDM could only be maternally transmitted. However, in the last few years, cases of paternal transmission of CDM have been described. We report a child with the CDM phenotype and 1, 800 CTG repeats born to an asymptomatic father with 65 repeats and compare this case to the four currently in the literature. We note that polyhydramnios was present in the majority of cases and that all fathers whose status was known had small repeat sizes and/or were asymptomatic at the time of their child's birth. Although it may be unusual, the possibility of the paternal transmission of CDM should be mentioned when counseling families with DM. The men who are at highest risk may be those who have small repeats sizes and are asymptomatic.

Developmental expression of myotonic dystrophy protein kinase in brain and its relevance to clinical phenotype.

To investigate the pathophysiologic role of myotonic dystrophy protein kinase (DMPK) in the brain in myotonic dystrophy (MD), the developmental characteristics of DMPK immunoreactivity in the central nervous system and its alteration with disease were studied. Eleven patients' brain with MD (5 congenital form, 6 adult form) were examined by immunohistochemistry using a specific antibody against synthetic DMPK peptides, antipeptide DM1, and compared with 30 control brains, including 16 age-matched controls. In controls, DM1-immunoreactive neurons appeared in the early fetal frontal cortex and cerebellar granule cell layer, persisting through 29 weeks of gestation and then disappearing. In contrast, immunoreactive neurons continued to persist in the cerebral cortex and cerebellar granule cell layer of MD patients. When we counted DM1-immunoreactive neurons, the increase over controls was greater in the congenital form of MD than in the adult form, and was greater in the cerebrum than in the cerebellum in both forms of MD. DM1 immunostaining was predominantly nuclear, mirroring Western blotting of subcellular fractions. Differences in DM1 expression related to development and to the two forms of MD may be closely related to the pathogenesis of mental retardation in this disease.

Myotonic dystrophy (DM) protein kinase levels in congenital and adult DM patients.

Myotonic dystrophy is caused by a (CTG)n trinucleotide repeat expansion located in the 3' untranslated region of the myotonic dystrophy protein kinase gene (DMPK). To date, the disease mechanism has proven elusive. The mutation would not be expected to affect kinase function and yet the disease is inherited in a dominant fashion. Mutant DMPK transcripts have been demonstrated to be retained in affected cell nuclei which could reduce DMPK protein levels and cause disease by haploinsufficiency. An alternate hypothesis is that the expansion confers a toxic gain of function on the transcript. In previous studies, various 52-55 kDa proteins have been detected using antisera targeted against DMPK and a decline of two of these candidates in disease tissues was reported. Current information now suggests that these proteins are not products of the myotonic dystrophy gene. We have characterised an antiserum which has been confirmed to recognise authentic 71 and 80 kDa isoforms of DMPK. Determination of the kinase levels in disease tissues with controls for patient age and tissue integrity demonstrates a modest overexpression in adult patients. In tissues from severely affected congenital patients only a slight decline is seen. This data argues against DMPK haploinsufficiency as a disease mechanism.

[A neonatal case of congenital myotonic dystrophy]. / Su un caso neonatale di distrofia miotonica congenita.

Congenital myotonic dystrophy is a rare autosomal disease, caused by an increased number of cytosine-thymine-guanine (CTG) trinucleotide on chromosome 19q. In the neonatal period the most peculiar clinical features are arthrogryposis, hypotonia, facial diplegia, respiratory and feeding difficulties. Clinical and electrical myotonic discharges are difficult to elicit in the newborn. We report a case of congenital myotonic dystrophy in a female newly born presenting with hypotonia, diaphragmatic paralysis, facial diplegia, and contractures of hips, knees and ankles. The diagnosis was confirmed by genetical study on lymphocyte DNA.

Combined maternal and congenital myotonic dystrophy managed by a multidisciplinary team.

Myotonic dystrophy is a rare autosomal dominant degenerative neuromuscular and neuroendocrine disease. Pregnancy can aggravate the maternal disease. Obstetrical complications include stillbirth, premature labor, polyhydramnion, abnormal presentation, prolonged labor, increased operative delivery, postpartum hemorrhages and anesthetic accidents. If the fetus is affected severe neonatal morbidity and mortality with arthrogryposis and mental retardation is common. We present a case where the family chose continuation of pregnancy with a known diagnosis of maternal and severe fetal myotonic dystrophy. A multidisciplinary team was used in the management of pregnancy and counseling the patient.

Aspectos genéticos y moleculares de la distrofía miotónica / Molecular and genetic aspects of myotonic distrophy

La distrofia miotónica es una enfermedad multisistémica, la cual afecta varios tejidos, como el músculo, el cerebro y algunos tejidos endocrinos. Presenta un patrón de herencia autosómico dominante con penetrancia incompleta y expresión variable. El defecto molecular es una expansión del trinucleótido CTG presente en la región 3 no codificante del gen DMPK, el cual codifica para una proteína quinasa. Existe una correlación positiva entre el número de repeticiones del trinocleótido CTG del alelo afectado y la severidad de la enfermedad y una correlación inversa entre la edad de expresión de la enfermedad y la longitud de la repetición. Se presenta inestabilidad de la repetición tanto mitótica como meióticamente, la primera provoca heterogeneidad somática la segunda causa aumento en el número de repeticiones con la trasmisión de padres a hijos. El mecanismo que conlleva a la expansión y su consecuencia a nivel celular no se conocen por el momento, aunque han surgido algunas hipótesis al respecto. La transmisión de la enfermedad en una familia dependerá tanto del sexo del padre que aporte la mutación como del tamaño de la repetición presente en los gametos. La forma congénita de la enfermedad ocurre casi exclusivamente por transmisión materna, mientras que las mutaciones negativas o contracciones ocurren por la vía paterna. Hasta el momento no existe tratamiento para la enfermedad, pues la fisiopatología de la misma no se conoce

CTG instability in myotonic dystrophy: molecular genetic analysis of families from south-eastern France with characteristics of intergenerational variation in CGT repeat numbers.

We report clinical, genetical and genealogical findings in 149 French families from the Rhône-Alpes area studied over a 5-year period. There was a significant excess of DM females compared to DM males with (CTG) repeat sizes between 1-2 kb. The mean maternal (CTG) repeat size was higher than paternal repeat size. Anticipation phenomenom was significantly higher after maternal than after paternal transmission. A significant correlation between parental (CTG) repeat size and intergenerational variation both in paternal and maternal transmissions was observed. The anticipation phenomenom was more important for sons than daughters particularly after maternal transmission. The mean (CTG) repeat size in mothers of CDM cases was about twice that of mothers of NCDM children. The risk of giving birth to a CDM child increased considerably when the number of maternal (CTG) repeats was over 300 (CTG). A significant excess of DM females was observed. They had on average 24% fewer children than male patients. Paternal transmission (63.6%) of DM occurred more frequently than maternal transmission (52.7%).

[Propofol anesthesia for a patient with congenital myotonic dystrophy].

We report the anesthetic management for a five year old boy with congenital myotonic dystrophy. The patient was scheduled for bilateral orchiopexy under general anesthesia. Anesthesia was induced with fentanyl 50 micrograms, vecuronium 0.6 mg and propofol 40 mg intravenously to facilitate tracheal intubation. During operation, we monitored train of four ratio (TOF) to confirm effect of muscle relaxation. Anesthesia was maintained with propofol (2 mg.kg-1.hr-1), nitrous oxide and caudal block. At the end of the operation, the patient recovered smoothly from anesthesia and post-operative course was uneventful. Congenital myotonic dystrophy presents many problems for the management of general anesthesia, because of respiratory or circulatory complications. In this case, we were careful not to use drugs which may cause respiratory or circulatory depression. We have demonstrated that anesthesia with propofol is a safe method for the anesthetic management of a patient with this disease.

Survival of a 30-week baby with congenital myotonic dystrophy initially ventilated for 55 days.

In previous reports, duration of initial ventilation exceeding 1 month almost always predicts non-survival of babies with congenital myotonic dystrophy. However, a baby with this condition survived beyond infancy after 55 days' ventilation. We describe this case in detail, explain why the baby survived and highlight the importance of individualized assessment, in addition to applying general prognostic terms described in the literature.