Tent-shaped mouth as a presenting symptom of congenital myotonic dystrophy

Congenital hypotonia: systematic approach for prenatal detection

OBJECTIVES

Congenital hypotonic conditions are rare and heterogeneous, and some are severely debilitating or lethal. Contrary to its prominent postnatal manifestation, the prenatal presentation of hypotonia is frequently subtle, inhibiting prenatal detection. We aimed to characterize the prenatal sonographic manifestation of congenital hypotonia throughout pregnancy, evaluate the yield of diagnostic tests and propose diagnostic models to increase its prenatal detection.

METHODS

This was a retrospective observational study of singleton pregnancies with congenital hypotonia, diagnosed either prenatally or immediately after birth, at a single tertiary center between the years 2012 and 2020. Prenatally, hypotonia was diagnosed if a fetus showed sonographic or clinical signs suggestive of hypotonia and had a confirmed underlying genetic condition, or in the absence of a known genetic abnormality if the fetus exhibited multiple prominent signs suggestive of hypotonia. Postnatally, it was diagnosed in neonates displaying reduced muscle tone leading to reduced spontaneous movement, reduced swallowing or feeding difficulty. We reviewed the medical records of pregnant patients carrying fetuses subsequently diagnosed with congenital hypotonia and assessed the yield of ultrasound scans, fetal magnetic resonance imaging, computed tomography and genetic tests. The detection rate of sonographic signs suggesting fetal hypotonia was calculated. The prevalence of non-specific signs, including polyhydramnios, persistent breech presentation, intrauterine growth restriction and maternal perception of reduced fetal movement, were compared between the study group and the local liveborn singleton population. Potential detection rates of different theoretical semiotic diagnostic models, differing in the threshold for referral for a targeted scan, were assessed based on the cohort's data.

RESULTS

The study group comprised 26 cases of congenital hypotonia, of which 10 (38.5%) were diagnosed prenatally, and the controls included 95 105 singleton live births, giving a prevalence of congenital hypotonia of 1:3658. Nuchal translucency thickness and the early anomaly scan at 13-17 weeks were normal in all 22 and 23 cases, respectively, in which this was performed. The mid-trimester scan performed at 19-25 weeks was abnormal in four of 24 (16.7%) cases. The overall prenatal detection rate of congenital hypotonic conditions in our cohort was 38.5%. Only cases which underwent a targeted scan were detected and, among the 16 cases which underwent this scan, the prenatal detection rate was 62.5% compared with 0% in pregnancies that did not undergo this scan (P = 0.003). An abnormal genetic diagnosis was obtained in 21 (80.8%) cases using the following modalities: chromosomal microarray analysis (CMA) in two (9.5%), whole-exome sequencing (WES) in 14 (66.7%) and methylation analysis in five (23.8%). CMA was abnormal in 8% (2/25) of the cases and WES detected a causative genetic mutation in 87.5% (14/16) of the cases in which these were performed. Comparison of non-specific signs in the study group with those in the local singleton population showed that hypotonic fetuses had significantly more polyhydramnios (64.0% vs 3.0%, P < 0.0001), persistent breech presentation (58.3% vs 4.2%, P < 0.0001), intrauterine growth restriction (30.8% vs 3.0%, P < 0.0001) and maternal perception of reduced fetal movement (32.0% vs 4.7%, P < 0.0001). Prenatally, the most commonly detected signs supporting a diagnosis of hypotonia were structural anomaly (62.5%, 10/16), reduced fetal movement (46.7%, 7/15), joint contractures (46.7%, 7/15) and undescended testes ≥ 30 weeks (42.9%, 3/7 males). Proposed diagnostic strategies that involved performing a targeted scan for a single non-specific ultrasound sign or two such signs, and then carrying out a comprehensive genetic evaluation for any additional sign, offered theoretical detection rates in our cohort of 88.5% and 57.7%, respectively.

CONCLUSIONS

Congenital hypotonic conditions are rare and infrequently detected prenatally. Sonographic signs are visible from the late second trimester. A targeted scan increases prenatal detection significantly. Comprehensive genetic testing, especially WES, is the cornerstone of diagnosis in congenital hypotonia. Theoretical diagnostic models which may increase prenatal detection are provided. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Open Bite Malocclusion and Orofacial Dysfunction in Patients with Myotonic Dystrophy Type 1 and Duchenne Muscular Dystrophy

Open bite (OB) is a common malocclusion in individuals with orofacial dysfunction and syndromes, especially in neuromuscular diseases.

OBJECTIVES

The objectives were to explore the prevalence of OB in myotonic dystrophy type 1 (DM1) and Duchenne muscular dystrophy (DMD) and to create and compare orofacial dysfunction profiles.

METHODS

In this database study, 143 individuals with DM1 and 99 with DMD were included. The Mun-H-Center questionnaire and observation chart were used together with the Nordic Orofacial Test -Screening (NOT-S) to create orofacial dysfunction profiles. OB was categorised as: lateral (LOB); anterior (AOB); severe anterior (AOBS); or both types of anterior OB (AOBTot). Descriptive and multivariate statistics were used to compare the OB prevalence and to study associations with orofacial variables, respectively.

RESULTS

There was a statistically significant difference in OB prevalence between the DM1 (37%) and DMD (49%) groups (p = 0.048). LOB was seen in < 1% of DM1 and 18% of DMD. LOB was associated with macroglossia and closed mouth posture, AOB with hypotonic lips, and open mouth posture and AOBS with hypotonic jaw muscles. The orofacial dysfunction profiles showed similar patterns, although the mean NOT-S total scores for DM1 and DMD were 4.2±2.8 (median 4.0, min-max 1-8) and 2.3±2.0 (median 2.0, min-max 0-8), respectively.

LIMITATIONS

The two groups were not age- or gender-matched.

CONCLUSION

OB malocclusion is common in patients with DM1 and DMD and is associated with different types of orofacial dysfunction. This study highlights the need for multi-disciplinary assessments to support tailored treatment strategies that improve or sustain orofacial functions.

Early Detection and Management of Prader-Willi Syndrome in Egyptian Patients

Prader-Willi syndrome (PWS) is a distinct neurodevelopmental disorder associated with the deletion within the chromosomal 15q11-q13 region or uniparental disomy of chromosome 15. The etiologic heterogeneity of PWS makes it very difficult to establish uniform diagnostic methods which would result in the detection of most affected individuals. The objective was to report the clinical criteria and oro-dental features in PWS, to report the effect of diet and laser acupuncture on PWS and highlighted an easy effective method for early diagnosis of individuals with PWS. The study included seventeen cytogenetically proven individuals with Prader-Willi syndrome. These patients were subjected to meticulous history taking, clinical examination including oro-dental examination, bone densitometry and neuropsychiatric evaluation. They received laser acupuncture sessions in addition to nutrition intervention. All cases had characteristic facies, hypotonia and various psychosocial difficulties. Other criteria of PWS were present in different percentages. Karyotyping revealed deletion 15q11-q13 in 6 patients, and fluorescence in situ hybridization (FISH) revealed a microdeletion in 15q11-q13 in the other 11 patients. To our knowledge, partial ankyloglossia, median grooved tongue and hypodontia have not previously been reported in PWS patients. Laser acupuncture sessions and diet were effective in weight decline for PWS patients. Our study emphasizes the importance of early detection of PWS, laser sessions, diet restriction and oro-dental examination in the follow up of patients with Prader Willi syndrome.

Prenatal diagnosis of congenital myopathies and muscular dystrophies

Congenital myopathies and muscular dystrophies constitute a genetically and phenotypically heterogeneous group of rare inherited diseases characterized by muscle weakness and atrophy, motor delay and respiratory insufficiency. To date, curative care is not available for these diseases, which may severely affect both life-span and quality of life. We discuss prenatal diagnosis and genetic counseling for families at risk, as well as diagnostic possibilities in sporadic cases.

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.