[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]

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.

[A neonatal case of congenital myotonic dystrophy]

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.

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.

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.

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.

Congenital neonatal myotonic dystrophy with persistent pulmonary hypertension and coma: a difficult diagnosis

The fulminant forms of congenital myotonic dystrophy, which rapidly lead to death, are difficult to diagnose. The case described illustrates the roles of persistent pulmonary hypertension in such a fatal form.

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.

Clinical and neuroimaging study of central nervous system in congenital myotonic dystrophy

We present the clinical and neuroimaging findings of five patients (four males, one female; mean age 12 years) affected by congenital myotonic dystrophy and the correlation with their molecular genetic analysis. At birth all five presented severe muscular weakness and hypotonia, associated with feeding difficulties and respiratory distress. In the same patients, congenital clubfoot or more generalized arthrogryposis was also evident. Lymphocyte DNA was characterized in each by a CTG repeat longer than 1300 in the region of the myotonic dystrophy gene in chromosome 19. The patients' neurological condition was evaluated by clinical examination, intelligence tests, electroencephalography, and brain magnetic resonance imaging. All five suffered from some impairment of intellectual function (IQ ranged from 52 to 79). In three a longitudinal evaluation of the cognitive deficit detected no deterioration. In all patients magnetic resonance imaging showed some degree of ventricular dilatation, loosely correlated to the cognitive impairment; in three there was hypoplasia of the corpus callosum and in two mild abnormalities of supratentorial white matter. The relationship between the size of the CTG repeat expansion found in lymphocyte DNA and the cerebral abnormalities appeared inconsistent in this unusual myoencephalopathy of the newborn.

Knowledge, views, and experience of 25 women with myotonic dystrophy

Twenty-five affected women of reproductive age known to the North West Regional Genetics Family Register (NWRGFR) were interviewed. A semistructured questionnaire, completed by the interviewer, was used to assess understanding and experience of the clinical and genetic aspects of myotonic dystrophy (MD) and attitudes to prenatal diagnosis (PND). Characteristic features of MD (muscle weakness and wasting and myotonia) were well known. Knowledge of other features and complications reflected experience. All subjects were aware that MD is inherited, but only 56% (14/25) knew the risk to their own children and subjects tended to overestimate this risk. Anticipation and maternal transmission of congenital myotonic dystrophy (CMD) were often misunderstood. Almost half of the subjects (12/25) perceived themselves to be moderately or severely affected and 40% (10/25) felt that their symptoms restricted daily life. Feelings of devastation, depression, worry about the future, and guilt at the risk of transmission to their children were described. Many subjects (10/25) said that the worst aspect of MD is the risk of transmission to their children. Over half (14/25) said that the risk of transmitting MD had influenced or would influence their own reproduction. Three-quarters of subjects who felt that MD had influenced their reproductive decisions (9/12) chose to limit their family or have no children; only 25% (3/12) requested PND. Subjects felt that the lack of information concerning clinical severity made PND for MD difficult to consider.

Prenatal diagnosis of congenital myotonic dystrophy and counseling of the pregnant mother: case report and literature review

The molecular basis of the myotonic dystrophy (MD) kinase gene is expansion of the CTG repeat at the 3'-untranslated region of the MD gene. Variability of the CTG repeat size in different tissues of affected individuals has been demonstrated. The objective of this report was to examine and review the feasibility of prenatal diagnosis of congenital myotonic dystrophy (CMD) in pregnant women with MD using CTG repeat sizes in amniocytes or villi. We present a case of a pregnant woman with MD who underwent prenatal diagnosis of MD using amniocytes. The repeat size in the amniocytes was smaller than the repeat size in the maternal leukocytes and smaller than the repeat size in the infant blood. The infant had CMD. We also reviewed the literature for reports on MD cases that were prenatally tested for CTG repeat size using amniocytes or chorionic villi. Data were tabulated based on the number of maternal CTG repeats, prenatal procedure [amniocentesis or chorionic villus sampling (CVS)], CTG repeat size in fetal tissue, fetal/infant blood, and pregnancy outcome. Twenty-seven pregnancies at risk for MD that underwent prenatal diagnosis were reported. Eleven (40.7%) of the 27 pregnancies underwent amniocentesis, and 16 (59.3%) underwent CVS. Fourteen patients (61%) demonstrated an increase in CTG repeat size in the amniocytes or villi compared with the maternal repeat size. Nine (33%) of the 27 pregnancies were terminated because of CMD risk. The outcomes of 11 (40.7%) pregnancies were consistent with diagnosis of CMD. CMD was diagnosed in fetuses demonstrating expansion or contraction of the CTG mutation in the amniocytes. Prenatal diagnosis of MD is possible by using mutation analysis on maternal and fetal DNA and detection of the CTG repeat expansion. Prenatal diagnosis of CMD is more complex. The possible lack of correlation between CTG repeat size in amniocytes, villi, and other fetal tissues is a potential limitation in prenatal diagnosis and counseling of CMD using CTG repeat size. Thus, prenatal diagnosis of CMD should be based on a combination of factors, including maternal pregnancy history, clinical findings, and cautious interpretation of maternal and fetal DNA analysis.

Contrasts in clinical presentation and genetic transmission of myotonic dystrophy

Myotonic dystrophy, the most common inherited neuromuscular disease, is an autosomal dominant muscular dystrophy characterized by myotonia and distal muscle weakness. It is caused by an increase in the number of cytosine-thymine-guanine (CTG) nucleotide repeats present on the long arm of chromosome 19. Two patients were evaluated, one with classic adult-onset myotonic dystrophy and the other with congenital myotonic dystrophy. Contrasts in the clinical features and genetic transmission of this disease and clinical management are reviewed.

Congenital myotonic dystrophy requiring prolonged endotracheal and noninvasive assisted ventilation: not a uniformly fatal condition

In this report we present two infants with congenital myotonic dystrophy (CMD) who were successfully weaned from prolonged ventilatory support using nasal continuous positive airway pressure (N-CPAP). The first infant received 127 days of endotracheal mechanical ventilation as part of 141 days of total ventilatory support, including N-CPAP; the second infant received 27 days of endotracheal mechanical ventilation as part of 84 days of total ventilatory support. Noninvasive N-CPAP facilitated weaning these two infants from ventilatory support, thereby minimizing the morbidity associated with prolonged intubation. The developmental outcomes of our two infants were comparable to infants not requiring prolonged endotracheal mechanical ventilation. We suggest that this noninvasive modality of ventilatory support may be advantageous in the management and beneficial to the outcome of infants with CMD who are respirator-dependent >30 days.

Myotonic dystrophy protein kinase gene expression in skeletal muscle from congenitally affected infants

Myotonic dystrophy (DM) is an autosomal dominant neuromuscular disorder characterized by marked variability of its clinical manifestations. The mutational basis of DM is an unstable (CTG)n trinucleotide repeat in the 3' untranslated region of the myotonic dystrophy protein kinase gene (DMPK). We used quantitative RT-PCR to determine DMPK mRNA levels in muscular biopsies from three congenitally affected (CDM) and two control infants. The CDM infants had increased DMPK mRNA levels, which were not correlated to increased expression of the mutant allele. This increase may be the consequence of a maturational muscular arrest, which may maintain an elevated level of DMPK mRNA until birth.

[Clinical and molecular genetic analyses of congenital myotonic dystrophy]

Myotonic dystrophy (DM) results from the amplification of an unstable CTG repeat in the 3' untranslated region of a transcript encoding an MtPK. Infants with congenital DM are shown to have on average a greater amplification of the CTG repeat than is seen in the noncongenital DM patients. The major clinical features of congenital DM are bilateral facial weakness, hypotonia, feeding difficulties, respiratory distress, delayed motor development and mental retardation. We present 6 patients, aged 11-35 years, from unrelated 5 families with clinical symptoms of congenital DM. The four of the patients were inherited paternally and only one showed a reduction in the CTG repeat size.

[Effect of maternal paternal transmissions on clinical manifestations of CTG repeat on myotonic dystrophy]

The increasing size of the CTG repeat in successive generations is considered to the molecular basis for anticipation in DM. Maternal offspring show severe clinical manifestation than paternal transmitted offspring. The intergenerational amplification of this repeat is influenced by the sex of the parent transmitting mutant allele, in that a greater average intergenerational amplification is seen on maternal transmission. Also in the severest form of CDM almost exclusively transmitted maternal allele, the number of repeats is generally higher than that seen in non-CDM. But whether the unknown another maternal factor influence defined children having large mutant allele from mother is important question. The parental bias based on the different methylation patterns, mitochondria genome or different expressions of mRNA species are unlikely. The maternal effect might be explained the differences of the expressions of mRNA according to alternating splicing. And intrauterine effect, chromosomal imprinting or other unknown maternal factors have been expected to be involved in the pathophysiology.

Instability of the (CTG)n repeat in congenital myotonic dystrophy

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Congenital myotonic dystrophy pathology and somatic mosaicism

We present the pathology and molecular genetic analysis of an infant with congenital myotonic dystrophy. The proband/infant, born at 35 weeks' gestational age to a mother with myotonic dystrophy and 750 CTG repeats, was markedly hypotonic and had severe cardiomyopathy. She died after 16 days of life. At autopsy, skeletal and heart muscles were immature and had a decrease in contractile elements. DNA CTG trinucleotide repeat analysis of the proband demonstrated 2,480 repeats in blood and a slightly greater number of repeats in skeletal muscles, viscera, and gray matter. Corresponding to the clinical course and pathology, cardiac tissues displayed somatic mosaicism, with repeats ranging from 2,760 to 3,220.

Paternal transmission of congenital myotonic dystrophy

We report a rare case of paternally transmitted congenital myotonic dystrophy (DM). The proband is a 23 year old, mentally retarded male who suffers severe muscular weakness. He presented with respiratory and feeding difficulties at birth. His two sibs suffer from childhood onset DM. Their late father had the adult type of DM, with onset around 30 years. Only six other cases of paternal transmission of congenital DM have been reported recently. We review the sex related effects on transmission of congenital DM. Decreased fertility of males with adult onset DM and contraction of the repeat upon male transmission contribute to the almost absent occurrence of paternal transmission of congenital DM. Also the fathers of the reported congenitally affected children showed, on average, shorter CTG repeat lengths and hence less severe clinical symptoms than the mothers of children with congenital DM. We conclude that paternal transmission of congenital DM is rare and preferentially occurs with onset of DM past 30 years in the father.

A study of the cognitive and psychological profile in 16 children with congenital or juvenile myotonic dystrophy

We report data on intelligence and on possibly associated psychopathology in 16 children and adolescents, between 7 and 18 years of age, with congenital or juvenile myotonic dystrophy. We found that all the subjects have an intelligence level below the population mean, four of them in the mentally retarded range. An unexpected number of subjects are in the clinical range on the Child Behavior Checklist. In nine of the 16 subjects, a child psychiatric diagnosis was found using a standardized psychiatric interview. The most frequent child psychiatric diagnosis was Attention Deficit Hyperactivity Disorder.

Myotonic dystrophy in pregnancy: a report of two cases within one family

myotonic dystrophy, also called the Curschmann-Steinert syndrome, is an autosomal dominant inherited neuromuscular disorder characterized by progressive muscular dystrophy, muscle weakness and myotonia, which can affect both mother and child. Complications may arise during pregnancy, delivery, including anaesthetic problems, and in the neonatal period. During pregnancy hydramnion can be a first sign of the disease leading to premature labor and also muscle weakness and myotonia can aggravate complicating the course of delivery. The affected neonate may display severe hypotonia, facial diplegia and respiratory distress. The clinical diagnosis can be confirmed by direct DNA analysis in serum and in chorionvillus biopsy material. In this case report two sisters with myotonic dystrophy are described, their pregnancies, deliveries and the outcome of their affected babies.

Pneumoperitoneum complicating mechanical ventilation in congenital myotonic dystrophy

Pneumoperitoneum is known as a disease caused by perforation of the gastrointestinal tract, but it has also been reported as a complication of mechanical ventilation. In a case of congenital myotonic dystrophy (CMyD), mechanical ventilation was performed to treat severe respiratory distress starting at birth, and then pneumomediastinum and pneumoperitoneum developed as complications 5 days after birth. The fact that the pneumoperitoneum improved when the ventilation pressure was reduced and the patient's course was observed, allowed us to rule out gastrointestinal perforation. It appeared that hypoplasia of the diaphragm may have been involved in the progression of pneumomediastinum to pneumoperitoneum in this patient. Mechanical ventilation is performed on many occasions in CMyD, and the development of pneumoperitoneum secondary to pulmonary air leak should always be borne in mind.

[Molecular genetic study in congenital myotonic dystrophy]

Congenital myotonic dystrophy (CMD) is the neonatal form of Steinert's myotonia. However, the symptoms and neuro-physiological findings are different from the classical adult form, there is a high mortality and early diagnosis of the condition is difficult. CMD occurs as a result of abnormal expansion of CTG triplets on chromosome 19. There is dominant autosomal transmission of this multi-systemic disorder, although when it occurs in children, it is the mother who is always the affected parent. Molecular genetic techniques enable unequivocal diagnosis of the condition, evaluation of anticipation and the possibility of offering genetic counselling to the families involved.

Haplotype analysis of congenital myotonic dystrophy patients from asymptomatic DM father

We report a family with congenital myotonic dystrophy (CDM) transmitted from an asymptomatic DM father; we analyzed the haplotype of this family by using polymorphism within and by flanking the DM protein kinase locus. One patient with congenital DM was homozygous for all markers studied, except for the expanded CTG repeats. Two other patients with congenital DM were heterozygous. One patient with congenital DM who was homozygous had greater clinical severity and more expanded CTG repeats than other CDM patients who were heterozygous. The asymptomatic father had a DM protomutation.

Detection of the CTG repeat expansion in congenital myotonic dystrophy

Myotonic dystrophy (DM) is caused by an abnormal expansion of an unstable CTG trinucleotide repeat in the 3' untranslated region of mRNA encoding a putative serine/threonine protein kinase. We analyzed 59 patients with DM (28 congenital DM families: 27 families with maternal transmission and 1 paternal transmission) and 27 normal control subjects to evaluate their CTG repeat size between DM patients and the normal controls, and to search for a correlation between the clinical characteristics of congenital DM (CDM) and CTG repeat expansions. Analysis was on the basis of the Southern blot and polymerase chain reaction (PCR) methods, and by direct sequencing of PCR amplified CTG repeats. Analysis of intergenerational differences in the CTG repeat size for mother-child pairs showed a positive correlation (y = 1.0384x + 1265.2, r2 = 0.311). In addition to the strong parental bias, this group showed genetic anticipation. There was a significant correlation of the CTG repeat expansion with disease severity. The largest CTG repeat expansion (2,293 CTG repeats) on average belonged to the severe CDM group, and the smallest (129 CTG repeats) to the subclinical DM group. The mutant allele of an asymptomatic father in the paternally transmitted pedigree revealed 75 CTG repeats, demonstrating that he was a DM protomutation carrier.

The movements of fetuses with congenital myotonic dystrophy in utero

The movements in two fetuses with congenital myotonic dystrophy were recorded on fetal actocardiograms. The two fetuses showed gross movements associated with FHR accelerations as normal fetus. One of them showed swallowing on amniofetogram, and hiccuping on fetal actocardiogram. Both, however, were extremely hypotonic and neither displayed any gross movement, respiratory movement or swallowing postnatally. Intubation and nasal feeding were required for a long period of time after birth in both cases. The buoyancy of amniotic fluid may help the affected fetus to make gross movement in utero.

Influence of the sex of the transmitting grandparent in congenital myotonic dystrophy

To analyse the influence of the sex of the transmitting grandparents on the occurrence of the congenital form of myotonic dystrophy (CDM), we have studied complete three generation pedigrees of 49 CDM cases, analysing: (1) the sex distribution in the grandparents' generation, and (2) the intergenerational amplification of the CTG repeat, measured in its absolute and relative values, between grandparents and the mothers of CDM patients and between the latter and their CDM children. The mean relative intergenerational increase in the 32 grandparent-mother pairs was significantly greater than in the 56 mother-CDM pairs (Mann-Whitney U test, p < 0.001). The mean expansion of the grandfathers (103 CTG repeats) was also significantly different from that seen in the grandmothers' group (154 CTG repeats) (Mann-Whitney U test, p < 0.01). This excess of non-manifesting males between the CDM grandparents' generation with a smaller CTG length than the grandmothers could suggest that the premutation has to be transmitted by a male to reach the degree of instability responsible for subsequent intergenerational CTG expansions without size constraints characteristic of the CDM range.

Mitochondrial DNA does not appear to influence the congenital onset type of myotonic dystrophy

Neither the maternal inheritance pattern nor the early onset of congenital myotonic dystrophy are fully explained. One possible mechanism is that mitochondrial DNA (mtDNA) mutations might interact with the DM gene product, producing an earlier onset than would otherwise occur. We have used Southern hybridisation to show that high levels of major rearrangements of mtDNA are not present in muscle of five and in blood of 35 patients with congenital myotonic dystrophy. We used sequence analysis to show that no one particular mtDNA morph appears to cosegregate with congenital onset. A minor degree of depletion of mtDNA compared with nuclear DNA was present in the muscle of five patients with congenital DM, but we propose that this is not the primary cause of the muscle pathology but secondary to it. We have not found evidence that mtDNA is involved in congenital myotonic dystrophy.

Congenital myotonic dystrophy: molecular diagnosis and clinical study

Recently, an unstable DNA fragment specific to myotonic dystrophy (MyD) was discovered. In affected individuals, a DNA fragment is found that is larger than in normal siblings. Our objectives were to show whether the results of DNA analysis agree with the disease severity and prognosis in congenital myotonic dystrophy (CMyD) by DNA analysis. We investigated three pregnancies (two studied retrospectively) in three families. We genotyped the family members with the Southern blots and the polymerase chain reaction (PCR) analysis. In one case a prenatal diagnosis was carried out using chorionic villus sampling. This report also presents the three cases of affected mothers and CMyD babies with their growth courses. We clarify four main problems in CMyD, namely, respiratory distress, delayed motor development, feeding difficulty, and delayed mental development. The allele size in the range of 10 to 13 kb tended to be present as the adult form of MyD, and 14 to 15 kb as the CMyD. The three CMyD cases whose alleles size in the range of 14 to 15 kb showed various forms of disease and prognosis. We reached the following conclusions: the disease severity and prognosis in babies with CMyD did not correlate with the result of DNA analysis. The DNA analysis is a useful test for prenatal diagnosis. However, it is impossible to predict the disease severity and prognosis in babies with CMyD.

[Proton MR spectroscopy of the brain in patients with congenital myotonic dystrophy]

Volume selective proton MR spectroscopy (1H-MRS) of the brain was performed on a 1.5T magnet in five patients with congenital muscular dystrophy (CMyD), 46 healthy children, and one healthy adult. Peaks of N-acetylaspartate (NAA), choline (Cho) and creatine (Cr) were observed in both patients and control groups on 1H-MRS, but lactate was not observed. 1H-MRS revealed an increase in the ratio of NAA/Cho and NAA/Cr, and a decrease in Cho/Cr ratio with age in control subjects. In patients with CMyD, the values of NAA/Cho ratio did not increase with age. The values of NAA/Cr ratio decreased with age. The values of Cho/Cr ratio decreased with age in both patient and control groups. At age more than 4 years, the values of NAA/Cho and NAA/Cr ratios were lower in patients with CMyD than in controls. The values of Cho/Cr ratio did not differ between CMyD and controls. These results suggest that in patients with CMyD, there is an NAA decrease and a developmental disorder of neurons in the brain.

Contribution of molecular analyses to the estimation of the risk of congenital myotonic dystrophy

A molecular analysis of the maternal and child CTG repeat size and intergenerational amplification was performed in order to estimate the risk of having a child with congenital myotonic dystrophy (CMD). In a study of 124 affected mother-child pairs (42 mother-CMD and 82 mother-non-CMD) the mean maternal CTG allele in CMD cases was three times higher (700 repeats) than in non-CMD cases (236 repeats). When the maternal allele was in the 50-300 repeats range, 90% of children were non-CMD. In contrast, when the maternal allele was greater than 300 repeats, 59% inherited the congenital form. Furthermore, the risk of having a CMD child is also related to the intergenerational amplification, which was significantly greater in the mother-CMD pairs than in the mother-non-CMD pairs. Although the risk of giving birth to a CMD child always exists for affected mothers, our data show that such a risk is considerably higher if the maternal allele is greater than 300 repeats.

Neuroimaging study of myotonic dystrophy. I. Magnetic resonance imaging of the brain

Magnetic resonance imaging scans of the brain were obtained in 13 patients with myotonic dystrophy, seven with congenital myotonic dystrophy and six with adult-type myotonic dystrophy. All seven patients with congenital myotonic dystrophy had ventriculomegaly and a low IQ (DQ). Cerebral white matter lesions were observed in six cases, a small corpus callosum in four cases, a small brainstem in two cases, and a cerebellar white matter lesion in one case. Cerebral white matter lesions were observed in five of the six cases with adult-type myotonic dystrophy of which one had ventriculomegaly. The IQ (DQ) was significantly lower in patients with congenital myotonic dystrophy than in those with adult-type myotonic dystrophy. The incidence of a small corpus callosum or ventricular enlargement was higher in congenital myotonic dystrophy than in adult-type myotonic dystrophy. These findings may be related to the presence of neurologic impairment in congenital myotonic dystrophy.

Prevalence of unsuspected myopathy in infants presenting for clubfoot surgery

The objective of this study was an evaluation of the prevalence of myopathies in paediatric patients scheduled for orthopaedic surgery (clubfoot) performed under regional anaesthesia. Seventeen infants scheduled for lower limb orthopaedic surgery were studied to verify coexisting neuromuscular disorders with electromyography and muscle biopsy during surgery. All surgical procedures were performed under caudal block or spinal anaesthesia, associated with light general anaesthesia. No major cardiorespiratory, neurological or malignant hyperthermic complications (muscle rigidity, arrhythmias, hyperpyrexia) were observed. Combined neurological, electromyographic and biopsy studies showed a high rate of myopathic changes (70%). Performance of clubfoot surgery under light general anaesthesia with regional techniques was free from any problems. The high rate of myopathic changes (70%) observed in the muscle biopsies suggests that precautions should be taken with paediatric patients for clubfoot surgery and a regional anaesthesia technique with adequate monitoring may be helpful to prevent possible malignant hyperthermia related problems.