Brain malformations involving the corpus callosum are common in children with developmental disabilities. We identified DCC mutations in four families and five sporadic individuals with isolated ...agenesis of the corpus callosum (ACC) without intellectual disability. DCC mutations result in variable dominant phenotypes with decreased penetrance, including mirror movements and ACC associated with a favorable developmental prognosis. Possible phenotypic modifiers include the type and location of mutation and the sex of the individual.
Benign hereditary chorea (BHC) is a rare autosomal dominant disorder characterised by childhood onset that tends to improve in adulthood. The associated gene, NKX2-1 (previously called TITF1), is ...essential for organogenesis of the basal ganglia, thyroid and lungs. The aim of the study was to refine the movement disorders phenotype. We also studied disease course and response to therapy in a large series of genetically proven patients.
We analysed clinical, genetic findings and follow-up data in 28 NKX2-1 mutated BHC patients from 13 families.
All patients had private mutations, including seven new mutations, three previously reported mutations and three sporadic deletions encompassing the NKX2-1 gene. Hypotonia and chorea were present in early infancy, with delayed walking ability (25/28); dystonia, myoclonus and tics were often associated. Attention deficit hyperactivity disorder (ADHD) was present in seven. Among the 14 patients followed-up until adulthood, nine had persistent mild chorea, two had near total resolution of chorea but persistent disabling prominent myoclonus and three recovered completely. Learning difficulties were observed in 20/28 patients, and three had mental retardation. Various combinations of BHC, thyroid (67%) and lung (46%) features were noted. We found no genotype-phenotype correlation. A rapid and sustained beneficial effect on chorea was obtained in 5/8 patients treated with tetrabenazine.
Early onset chorea preceded by hypotonia is suggestive of BHC. Associated thyroid or respiratory disorders further support the diagnosis and call for genetic studies. Tetrabenazine may be an interesting option to treat disabling chorea.
Isolated corpus callosum dysgenesis (CCD) is a congenital malformation which occurs during early development of the brain. In this study, we aimed to identify and describe its consequences beyond the ...lack of callosal fibres, on the morphology, microstructure and asymmetries of the main white matter bundles with diffusion imaging and fibre tractography. Seven children aged between 9 and 13 years old and seven age- and gender-matched control children were studied. First, we focused on bundles within the mesial region of the cerebral hemispheres: the corpus callosum, Probst bundles and cingulum which were selected using a conventional region-based approach. We demonstrated that the Probst bundles have a wider connectivity than the previously described rostrocaudal direction, and a microstructure rather distinct from the cingulum but relatively close to callosal remnant fibres. A sigmoid bundle was found in two partial ageneses. Second, the corticospinal tract, thalamic radiations and association bundles were extracted automatically via an atlas of adult white matter bundles to overcome bias resulting from a priori knowledge of the bundles' anatomical morphology and trajectory. Despite the lack of callosal fibres and the colpocephaly observed in CCD, all major white matter bundles were identified with a relatively normal morphology, and preserved microstructure (i.e. fractional anisotropy, mean diffusivity) and asymmetries. Consequently the bundles' organisation seems well conserved in brains with CCD. These results await further investigations with functional imaging before apprehending the cognition variability in children with isolated dysgenesis.
•59% of the children who had a MMC fetal repair had a hindbrain herniation reversal at birth.•75% of the children who had a MMC fetal repair did not require a ventriculo-peritoneal shunt in the first ...year of life.•At age 3, 75% of the children who had a MMC fetal repair were able to walk with orthotics or independently and 100% attended school.•Fetal surgery for MMC seems to have no benefit on children's sphincter functions.
Open fetal myelomeningocele (MMC) surgery is currently the standard of care option for prenatal MMC repair. We described the population referred to our center and reviewed outcome after open fetal MMC repair.
All patients referred to our center for MMC were reviewed from July 2014 to June 2020. For all the patients who underwent fetal MMC repair, surgical details, maternal characteristics and data from the neonatal to the three-years-old evaluations were collected.
Among the 126 patients referred to our center, 49.2% were eligible and 27.4% (n = 17) of them underwent fetal MMC repair. Average gestational age at fetal surgery was 24+6 weeks. There was no case of fetal complication and the only maternal complication was one case of transfusion. We recorded 70% of premature rupture of membranes and 47% of premature labor. Average gestational age at delivery was 34+2 weeks and no patient delivered before 30 weeks. There was no case of uterine scar dehiscence or maternal complication during cesarean section. After birth, 59% of the children had a hindbrain herniation reversal. At 1-year-old, 42% were assigned a functional level of one or more better than expected according to the prenatal anatomic level and 25% required a ventriculoperitoneal shunt. At 3-year-old, all the children attended school and 75% were able to walk with orthotics or independently.
Open fetal surgery enables anatomical repair of the MMC lesion, a potential benefit on cerebral anomalies and motor function, with a low rate of perinatal and maternal complications.
Corpus callosum agenesis (CCA) is a brain malformation associated with a wide clinical spectrum including intellectual disability (ID) and an etiopathological complexity. We identified a novel ...missense G424R mutation in the X-linked p21-activated kinase 3 (PAK3) gene in a boy presenting with severe ID, microcephaly and CCA and his fetal sibling with CCA and severe hydrocephaly. PAK3 kinase is known to control synaptic plasticity and dendritic spine dynamics but its implication is less characterized in brain ontogenesis. In order to identify developmental functions of PAK3 impacted by mutations responsible for CCA, we compared the biochemical and biological effects of three PAK3 mutations localized in the catalytic domain. These mutations include two “severe” G424R and K389N variants (responsible for severe ID and CCA) and the “mild” A365E variant (responsible for nonsyndromic mild ID). Whereas they suppressed kinase activity, only the two severe variants displayed normal protein stability. Furthermore, they increased interactions between PAK3 and the guanine exchange factor αPIX/ARHGEF6, disturbed adhesion point dynamics and cell spreading, and severely impacted cell migration. Our findings highlight new molecular defects associated with mutations responsible for severe clinical phenotypes with developmental brain defects.
•A novel PAK3 variant (p.Gly424Arg) with severe phenotype has been identified.•Mutation impairs kinase activity and tends to increase PIX binding.•Variant expression affects cell morphology and migration.•Biological impairments may be correlated with clinical severity.
Background
Pericallosal lipomas are often associated with corpus callosum dysgenesis. The diagnosis of lipoma, suggested on ultrasonography, relies on the classic T1 hyperintensity on magnetic ...resonance imaging (MRI). However, this feature may be absent prenatally.
Objective
Our objective was to study the changes of T1 intensity in fetal lipomas with comparison to postnatal/postmortem data and to assess the factors influencing the signal variations of pericallosal lipomas on prenatal MRI.
Materials and methods
Patients with callosum dysgenesis and interhemispheric hyperechogenicity suggestive of a pericallosal lipoma with available postnatal or postmortem data were included. Gestational age, lipoma size and pattern, corpus callosum size and changes in fetal fat T1 intensity were recorded. Comparison with postmortem neuropathology was available for one fetus.
Results
Eleven patients with callosum dysgenesis and pericallosal lipomas (seven curvilinear and four tubulonodular) were included. All MRI scans were performed in the third trimester. Curvilinear lipomas were thinner and six cases were associated with prenatal T1 iso-intensity. Typical T1 hyperintensity appeared on postnatal MRI only. All tubulonodular lipomas were much larger and showed prenatal T1 hyperintensity. In two patients, the lipoma increased in size on postnatal MRI.
Conclusion
The type and size of a lipoma influence T1 prenatal intensity. Absence of T1 intensity was observed in curvilinear lipomas only. Curvilinear lipomas are much thinner. Changes in T1 intensity may also be related to fat maturation within the lipoma and, subsequently, to gestational age. In the case of callosum dysgenesis, absence of prenatal T1 pericallosal hyperintensity should not exclude the diagnosis of pericallosal lipoma.
Infection with parvovirus B19 (B19V) during pregnancy may cause severe fetal anemia, hydrops, and fe tal death. Furthermore, neurodevelopmental impairment among survivors may occur despite ...appropriate prenatal management, including intrauterine transfusion (IUT).
Our primary objective was to describe cerebral lesions on MRI in fetuses with severe anemia requiring IUT for B19V infection. Our secondary objective was to search for clinical and biological characteristics associated with the occurrence of such lesions.
We performed a retrospective review of data on fetuses infected with B19V and requiring at least one IUT between 2005 and 2016. Fetuses with abnormal cerebral MRI results in the 3rd trimester were compared to those with normal MRI results.
Of 34 transfused fetuses, 26 children were born at full term. Five intrauterine fetal deaths, 1 neonatal death, and 2 terminations of pregnancy occurred. Cerebral anomalies were observed in 7/27 fetuses on MRI, including cerebellar hemorrhage or a small cerebellum. Only viral load in fetal blood appeared to be associated with brain lesions (11.5 log10 copies/mL 10.5-12.5 in case of abnormal MRI results vs. 9.5 log10 copies/mL 7.8-10.0; p = 0.05).
Among the fetuses transfused for B19V infection, 26% presented with prenatal abnormal cerebral imaging results. In our study, viral load in fetal blood appeared to be the only factor associated with fetal brain lesions.
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