A recessive PRDM13 mutation results in congenital hypogonadotropic hypogonadism and cerebellar hypoplasia.

The positive regulatory (PR) domain containing 13 (PRDM13) putative chromatin modifier and transcriptional regulator functions downstream of the transcription factor PTF1A, which controls GABAergic fate in the spinal cord and neurogenesis in the hypothalamus. Here, we report a recessive syndrome associated with PRDM13 mutation. Patients exhibited intellectual disability, ataxia with cerebellar hypoplasia, scoliosis, and delayed puberty with congenital hypogonadotropic hypogonadism (CHH). Expression studies revealed Prdm13/PRDM13 transcripts in the developing hypothalamus and cerebellum in mouse and human. An analysis of hypothalamus and cerebellum development in mice homozygous for a Prdm13 mutant allele revealed a significant reduction in the number of Kisspeptin (Kiss1) neurons in the hypothalamus and PAX2+ progenitors emerging from the cerebellar ventricular zone. The latter was accompanied by ectopic expression of the glutamatergic lineage marker TLX3. Prdm13-deficient mice displayed cerebellar hypoplasia and normal gonadal structure, but delayed pubertal onset. Together, these findings identify PRDM13 as a critical regulator of GABAergic cell fate in the cerebellum and of hypothalamic kisspeptin neuron development, providing a mechanistic explanation for the cooccurrence of CHH and cerebellar hypoplasia in this syndrome. To our knowledge, this is the first evidence linking disrupted PRDM13-mediated regulation of Kiss1 neurons to CHH in humans.

Yin Yang 1 is critical for mid-hindbrain neuroepithelium development and involved in cerebellar agenesis.

The highly conserved and ubiquitously expressed transcription factor Yin Yang 1 (Yy1), was named after its dual functions of both activating and repressing gene transcription. Yy1 plays complex roles in various fundamental biological processes such as the cell cycle progression, cell proliferation, survival, and differentiation. Patients with dominant Yy1 mutations suffer from central nervous system (CNS) developmental defects. However, the role of Yy1 in mammalian CNS development remains to be fully elucidated. The isthmus organizer locates to the mid-hindbrain (MHB) boundary region and serves as the critical signaling center during midbrain and cerebellar early patterning. To study the function of Yy1 in mesencephalon/ rhombomere 1 (mes/r1) neuroepithelium development, we utilized the tissue-specific Cre-LoxP system and generated a conditional knockout mouse line to inactivate Yy1 in the MHB region. Mice with Yy1 deletion in the mes/r1 region displayed cerebellar agenesis and dorsal midbrain hypoplasia. The Yy1 deleted neuroepithelial cells underwent cell cycle arrest and apoptosis, with the concurrent changes of cell cycle regulatory genes expression, as well as activation of the p53 pathway. Moreover, we found that Yy1 is involved in the transcriptional activation of Wnt1 in neural stem cells. Thus, our work demonstrates the involvement of Yy1 in cerebellar agenesis and the critical function of Yy1 in mouse early MHB neuroepithelium maintenance and development.

Curcumin Prevents Cerebellar Hypoplasia and Restores the Behavior in Hyperbilirubinemic Gunn Rat by a Pleiotropic Effect on the Molecular Effectors of Brain Damage.

Bilirubin toxicity to the central nervous system (CNS) is responsible for severe and permanent neurologic damage, resulting in hearing loss, cognitive, and movement impairment. Timely and effective management of severe neonatal hyperbilirubinemia by phototherapy or exchange transfusion is crucial for avoiding permanent neurological consequences, but these therapies are not always possible, particularly in low-income countries. To explore alternative options, we investigated a pharmaceutical approach focused on protecting the CNS from pigment toxicity, independently from serum bilirubin level. To this goal, we tested the ability of curcumin, a nutraceutical already used with relevant results in animal models as well as in clinics in other diseases, in the Gunn rat, the spontaneous model of neonatal hyperbilirubinemia. Curcumin treatment fully abolished the landmark cerebellar hypoplasia of Gunn rat, restoring the histological features, and reverting the behavioral abnormalities present in the hyperbilirubinemic rat. The protection was mediated by a multi-target action on the main bilirubin-induced pathological mechanism ongoing CNS damage (inflammation, redox imbalance, and glutamate neurotoxicity). If confirmed by independent studies, the result suggests the potential of curcumin as an alternative/complementary approach to bilirubin-induced brain damage in the clinical scenario.

WNT1-associated osteogenesis imperfecta with atrophic frontal lobes and arachnoid cysts.

A rare form of osteogenesis imperfecta (OI) caused by Wingless-type MMTV integration site family 1 (WNT1) mutations combines central nervous system (CNS) anomalies with the characteristic increased susceptibility to fractures. We report an additional case where arachnoid cysts extend the phenotype, and that also confirms the association of intellectual disabilities with asymmetric cerebellar hypoplasia here. Interestingly, if the cerebellum is normal in this disorder, intelligence is as well, analogous to an association with similar delays in a subset of patients with sporadic unilateral cerebellar hypoplasia. Those cases typically appear to represent vascular disruptions, and we suggest that most brain anomalies in WNT1-associated OI have vascular origins related to a role for WNT1 in CNS angiogenesis. This unusual combination of benign cerebellar findings with effects on higher functions in these two situations raises the possibility that WNT1 is involved in the pathogenesis of the associated sporadic cases as well. Finally, our patient reacted poorly to pamidronate, which appears ineffective with this form of OI, so that a lack of improvement is an indication for molecular testing that includes WNT1.

Nystagmus And Beyond: A Rare Ocular Motility Disorder.

Joubert syndrome is a rare autosomal recessive disorder predominantly involving the cerebellar vermis and brain stem. It is characterized clinically by global developmental delay, abnormal ocular movements, hypotonia, ataxia, intellectual disability and neonatal breathing abnormalities. Due to its uncommon and unconventional presentation, its diagnosis is usually delayed. Diagnosis of this atypical disease essentially relies upon the atypical finding of the "molar tooth" sign on Magnetic Resonance Imaging (MRI). We report a case of a 5-year-old boy who presented with abnormal eye movements, regression of milestones and developmental delay. MRI investigation revealed the distinctive molar tooth sign and bat wing shaped 4th ventricle. It requires high levels of clinical suspicion and holistic approach to such children who present with delayed milestones and abnormal eye movements, to reach at early detection and diagnosis of such rare pathologies.

Absence of associative motor learning and impaired time perception in a rare case of complete cerebellar agenesis.

Primary cerebellar agenesis (PCA), a brain disease where the cerebellum does not develop, is an extremely rare congenital disease with only eleven living cases reported thus far. Studies of the PCA case will thus provide valuable insights into the necessity of cerebellar development for controlling and modulating cognitive functions of the brain. In this follow-up study, we further investigated the performance of associative learning and time perception of a 26-year-old female complete PCA case. We assessed whether delayed eyeblink conditioning (EBC), which represents prototypical associative motor learning function of the cerebellum, could be partially compensated by the extracerebellar brain regions in complete absence of the cerebellum. We also assessed whether the cerebellum, a critical brain region for millisecond-range interval timing, is essential for perception of the second-range time interval. Twelve neurotypical age-matched individuals were used as controls. We found that although the complete PCA patient had only mild to moderate motor deficits, she was unable to perform the delayed EBC even after 1-week of extensive training. Additionally, the PCA patient also performed poorly during time reproduction experiments in which she overproduced the millisecond-range time intervals, while underproduced the second-range time intervals. The PCA patient also failed to perform the temporal eyeblink conditioning with a 5 s fixed interval as the conditioned stimulus. These results indicate that the cerebellum is indispensable for associative motor learning and involved in timing of sub-second intervals, as well as in the perception of second-range intervals.

MRI analysis of cerebellar and vestibular developmental phenotypes in Gbx2 conditional knockout mice.

PURPOSE: Our aim in this study was to apply three-dimensional MRI methods to analyze early postnatal morphological phenotypes in a Gbx2 conditional knockout (Gbx2-CKO) mouse that has variable midline deletions in the central cerebellum, reminiscent of many human cerebellar hypoplasia syndromes. METHODS: In vivo three-dimensional manganese-enhanced MRI at 100-µm isotropic resolution was used to visualize mouse brains between postnatal days 3 and 11, when cerebellum morphology undergoes dramatic changes. Deformation-based morphometry and volumetric analysis of manganese-enhanced MRI images were used to, respectively, detect and quantify morphological phenotypes in Gbx2-CKO mice. Ex vivo micro-MRI was performed after perfusion-fixation with supplemented gadolinium for higher resolution (50-µm) analysis. RESULTS: In vivo manganese-enhanced MRI and deformation-based morphometry correctly identified known cerebellar defects in Gbx2-CKO mice, and novel phenotypes were discovered in the deep cerebellar nuclei and the vestibulo-cerebellum, both validated using histology. Ex vivo micro-MRI revealed subtle phenotypes in both the vestibulo-cerebellum and the vestibulo-cochlear organ, providing an interesting example of complementary phenotypes in a sensory organ and its associated brain region. CONCLUSION: These results show the potential of three-dimensional MRI for detecting and analyzing developmental defects in mouse models of neurodevelopmental diseases.

Unusual association of Arnold-Chiari malformation and vitamin B12 deficiency.

Arnold-Chiari malformations are a group of congenital or acquired defects associated with the displacement of cerebellar tonsils into the spinal canal. First described by Chiari (1891), this has various grades of severity and involves various parts of neuraxis, for example, cerebellum and its outputs, neuro-otological system, lower cranial nerves, spinal sensory and motor pathways. The symptomatology of Arnold-Chiari malformations may mimic multiple sclerosis, primary headache syndromes, spinal tumours and benign intracranial hypertension. We highlighted a case of Chiari type I malformation, who presented with posterolateral ataxia associated with significant vitamin B(12) deficiency. The patient was supplemented with vitamin B(12) injections and showed remarkable improvement at follow-up after 3 months.

Insertion of 16 amino acids in the BAR domain of the oligophrenin 1 protein causes mental retardation and cerebellar hypoplasia in an Italian family.

We observed a three-generation family with two maternal cousins and an uncle affected by mental retardation (MR) with cerebellar hypoplasia. X-linked inheritance and the presence of cerebellar malformation suggested a mutation in the OPHN1 gene. In fact, mutational screening revealed a 2-bp deletion that abolishes a donor splicing site, resulting in the inclusion of the initial 48 nucleotides of intron 7 in the mRNA. This mutation determines the production of a mutant oligophrenin 1 protein with 16 extra amino acids inserted in-frame in the N-terminal BAR (Bin1/amphiphysin/Rvs167) domain. This is the first case of a mutation in OPHN1 that does not result in the production of a truncated protein or in its complete loss. OPHN1 (ARHGAP41) encodes a GTPase-activating (GAP) protein belonging to the GRAF subfamily characterized by an N-terminal BAR domain, followed by a pleckstrin-homology (PH) domain and the GAP domain. GRAF proteins play a role in endocytosis and are supposed to dimerize via their BAR domain, that induces membrane curvature. The extra 16 amino acids cause the insertion of 4.4 turns in the third alpha-helix of the BAR domain and apparently impair the protein function. In fact, the clinical phenotype of these patients is identical to that of patients with loss-of-function mutations.

The neuroradiological findings of children with developmental language disorder.

PURPOSE: To investigate the general characteristics of glucose metabolism distribution and the functional deficit in the brain of children with developmental language delay (DLD), we compared functional neuroradiological studies such as positron emission tomography (PET) of a patient group of DLD children and a control group of attention- deficit hyperactivity disorder (ADHD) children. PATIENTS AND METHODS: Seventeen DLD children and 10 ADHD children under 10 years of age were recruited and divided into separate groups consisting of children less than 5 years of age or between 5 and 10 years of age. The PET findings of 4 DLD children and 6 control children whose ages ranged from 5 to 10 years were compared by Statistical Parametric Mapping (SPM) analysis. RESULTS: All of the DLD children revealed grossly normal findings in brain MRIs, however, 87.5% of them showed grossly abnormal findings in their PET studies. Abnormal findings were most frequent in the thalamus. The patient group showed significantly decreased glucose metabolism in both frontal, temporal and right parietal areas (p < 0.005) and significantly increased metabolism in both occipital areas (p < 0.05) as compared to the control group. CONCLUSION: This study reveals that DLD children may show abnormal findings on functional neuroradiological studies, even though structural neuroradiological studies such as a brain MRI do not show any abnormal findings. Frequent abnormal findings on functional neuroradiological studies of DLD children, especially in the subcortical area, suggests that further research with quantitative assessments of functional neuroradiological studies recruiting more DLD children and age-matched normal controls could be helpful for understanding the pathophysiology of DLD and other disorders confined to the developmental disorder spectrum.

The Neuroradiological Findings of Children with Developmental Language Disorder

PURPOSE: To investigate the general characteristics of glucose metabolism distribution and the functional deficit in the brain of children with developmental language delay (DLD), we compared functional neuroradiological studies such as positron emission tomography (PET) of a patient group of DLD children and a control group of attention- deficit hyperactivity disorder (ADHD) children. PATIENTS AND METHODS: Seventeen DLD children and 10 ADHD children under 10 years of age were recruited and divided into separate groups consisting of children less than 5 years of age or between 5 and 10 years of age. The PET findings of 4 DLD children and 6 control children whose ages ranged from 5 to 10 years were compared by Statistical Parametric Mapping (SPM) analysis. RESULTS: All of the DLD children revealed grossly normal findings in brain MRIs, however, 87.5% of them showed grossly abnormal findings in their PET studies. Abnormal findings were most frequent in the thalamus. The patient group showed significantly decreased glucose metabolism in both frontal, temporal and right parietal areas (p < 0.005) and significantly increased metabolism in both occipital areas (p < 0.05) as compared to the control group. CONCLUSION: This study reveals that DLD children may show abnormal findings on functional neuroradiological studies, even though structural neuroradiological studies such as a brain MRI do not show any abnormal findings. Frequent abnormal findings on functional neuroradiological studies of DLD children, especially in the subcortical area, suggests that further research with quantitative assessments of functional neuroradiological studies recruiting more DLD children and age-matched normal controls could be helpful for understanding the pathophysiology of DLD and other disorders confined to the developmental disorder spectrum.

The level of sonic hedgehog signaling regulates the complexity of cerebellar foliation.

Foliation of the mouse cerebellum occurs primarily during the first 2 weeks after birth and is accompanied by tremendous proliferation of granule cell precursors (GCPs). We have previously shown that sonic hedgehog (Shh) signaling correlates spatially and temporally with fissure formation, and that Gli2 is the main activator driving Shh induced proliferation of embryonic GCPs. Here, we have tested whether the level of Shh signaling regulates the extent of cerebellar foliation. By progressively lowering signaling by removing Gli1 and Gli2 or the Shh receptor smoothened, we found the extent of foliation is gradually reduced, and that this correlates with a decrease in the duration of GCP proliferation. Importantly, the pattern of the remaining fissures in the mutants corresponds to the first fissures that form during normal development. In a complementary manner, an increase in the level and length of Shh signaling results in formation of an extra fissure in a position conserved in rat. The complexity of cerebellar foliation varies greatly between vertebrate species. Our studies have uncovered a mechanism by which the level and length of Shh signaling could be integral to determining the distinct number of fissures in each species.

Postnatal cerebellar defects in mice deficient in methylenetetrahydrofolate reductase.

Patients with severe deficiency of methylenetetrahydrofolate reductase (MTHFR) suffer from a wide variety of neurological problems, which can begin in the neonatal period. MTHFR is a critical enzyme in folate metabolism; the product of the MTHFR reaction, 5-methyltetrahydrofolate, is required for homocysteine remethylation to methionine and synthesis of S-adenosylmethionine (SAM). To understand the mechanisms by which MTHFR deficiency leads to significant neuropathology, we examined early postnatal brain development in mice with a homozygous knockout of the Mthfr gene. These mice displayed a dramatically reduced size of the cerebellum and cerebral cortex, with enlarged lateral ventricles. Mthfr deficiency affected granule cell maturation, but not neurogenesis. Depletion of external granule cells and disorganization of Purkinje cells were mainly confined to the anterior lobules of mutant cerebella. Decreased cellular proliferation and increased cell death contributed to the granule cell loss. Reduced expression of Engrailed-2 (En2), Reelin (Reln) and inositol 1,4,5-triphosphate receptor type 1 (Itpr1) genes was observed in the cerebellum. Supplementation of Mthfr(+/-) dams with an alternate methyl donor, betaine, reduced cerebellar abnormalities in the Mthfr(-/-) pups. Our findings suggest that MTHFR plays a role in cerebellar patterning, possibly through effects on proliferation or apoptosis.

Hypothalamic hamartoma, cerebellar hypoplasia, facial dysmorphism and very atypical combination of polydactyly: is it a new variant of oro-facio-digital syndrome?

We describe a newborn with multiple congenital anomalies consistent with an oro-facio-digital syndrome (OFDS). These are a group of inherited syndromes that have in common anomalies of the tongue (bifid or lobulated tongue with hamartomas), the face (median cleft lip) and the digits (brachydactyly, polydactyly, clinodactyly and/or syndactyly). OFDS has been classified into 11 types. The case described in this paper had manifestations overlapping with OFDS II (Mohr) and OFDS IV (Mohr-Majewski) and OFDS VI (Varadi). We propose that the present patient has a new variation of the OFDS due to the co-existence of the very atypical combination of polydactyly, cerebellar hypoplasia, hypothalamic hamartoma and classical facial findings of OFDS.

Spatial pattern of sonic hedgehog signaling through Gli genes during cerebellum development.

The cerebellum consists of a highly organized set of folia that are largely generated postnatally during expansion of the granule cell precursor (GCP) pool. Since the secreted factor sonic hedgehog (Shh) is expressed in Purkinje cells and functions as a GCP mitogen in vitro, it is possible that Shh influences foliation during cerebellum development by regulating the position and/or size of lobes. We studied how Shh and its transcriptional mediators, the Gli proteins, regulate GCP proliferation in vivo, and tested whether they influence foliation. We demonstrate that Shh expression correlates spatially and temporally with foliation. Expression of the Shh target gene Gli1 is also highest in the anterior medial cerebellum, but is restricted to proliferating GCPs and Bergmann glia. By contrast, Gli2 is expressed uniformly in all cells in the developing cerebellum except Purkinje cells and Gli3 is broadly expressed along the anteroposterior axis. Whereas Gli mutants have a normal cerebellum, Gli2 mutants have greatly reduced foliation at birth and a decrease in GCPs. In a complementary study using transgenic mice, we show that overexpressing Shh in the normal domain does not grossly alter the basic foliation pattern, but does lead to prolonged proliferation of GCPs and an increase in the overall size of the cerebellum. Taken together, these studies demonstrate that positive Shh signaling through Gli2 is required to generate a sufficient number of GCPs for proper lobe growth.

Cerebellar and frontal lobe hypoplasia in fetuses with trisomy 21: usefulness as combined US markers.

PURPOSE: To confirm that cerebellar hypoplasia is ultrasonographically recognizable in second-trimester fetuses with Down syndrome and determine whether the combination of frontal lobe shortening and cerebellar hypoplasia is superior to either measurement alone as a marker of this abnormality. MATERIALS AND METHODS: The frontothalamic distance (FTD) and transcerebellar diameter (TCD) were measured in 52 middle-trimester fetuses with euploid karyotypes and in 52 fetuses with Down syndrome. Receiver operating characteristic (ROC) curves were constructed with various thresholds for observed-to-expected ratios (O/Es) of the FTD, TCD, and average of these two parameters. RESULTS: The area under the average ROC curve, 0.80, was greater than that for either the FTD alone (0.75) or the TCD alone (0.76). At a 6% false-positive rate, the sensitivity for the detection of Down syndrome obtained with the average parameter was 34% better than that obtained with only the FTD and 12% better than that obtained with only the TCD. With an O/E threshold of 0.92 for the average parameter, an odds ratio of 16.3 and positive predictive value of 12.7% in the high-risk population were achieved. CONCLUSION: Although both measurements are individually statistically significant, the combination of TCD and FTD measurements may be superior to the use of either parameter alone as a marker of trisomy 21.

Aventriculi associated with holoprosencephaly.

Recently, an 11 year-old girl was reported with fusion of the cerebral hemispheres (holoprosencephaly), and cerebellar hemispheres (rhombencephalosynapsia), without identifiable ventricles. The condition was named as aventriculi. In this paper, the second example of aventriculi is reported in a 1 month-old girl by MR imaging.

Meningoencephalocele associated with Tripterygium wilfordii treatment.

We treated a male infant with occipital meningoencephalocele associated with the taking of Tripterygium wilfordii. The infant was delivered normally at 38 weeks of gestation with a huge cystic mass protruding from the occiput. He was diagnosed with occipital meningoencephalocele and cerebellar agenesis. His mother had taken T. wilfordii for rheumatoid arthritis early in her pregnancy. T. wilfordii is a herbal medicine used for rheumatoid arthritis and male contraception. Since its toxicity is high and its use during pregnancy is restricted, it is the most likely cause of this infant's anomalies.

Probable cerebellar abnormality on N-isopropyl-(iodine-123)-p-iodoamphetamine single photon emission computed tomography scans in an epileptic patient receiving long-term high-dose phenytoin therapy.

Quantitative assessment of regional cerebral blood flow (rCBF) was performed in a 22-year-old man with intractable temporal lobe epilepsy on long-term high-dose phenytoin (PHT) therapy, using single photon emission computed tomography (SPECT) with N-isopropyl-(iodine-123)-p-iodoamphetamine. In all the SPECT scans repeated three times with changes in the PHT dose, absolute rCBF values were lower in most of the cerebral and cerebellar regions measured, as compared with 5 normal subjects matched for sex and age, and 22 normal subjects including the 5 men. Both the cerebellar to frontal rCBF ratio and cerebellar to cerebral rCBF ratio in the patient persistently showed low values, probably reflecting abnormal relative cerebellar hypoperfusion, whereas X-ray computed tomography and magnetic resonance brain imaging showed no abnormal findings. However, this probable cerebellar abnormality on SPECT was to some degree reversible with decreases in the PHT dose. These results suggest the utility of SPECT scans for early detection of cerebellar abnormalities known to be often present in epileptic patients, and imply a risk of long-term high-dose PHT therapy.

[Intracranial anomalies in myelomeningocele--observation with magnetic resonance (MR) imaging].

It is generally accepted that myelomeningocele frequently associates with Arnold-Chiari malformation and other anomalies of the intracranial structures. The ventriculographic and CT findings of the patients with myelomeningocele has been reported. Magnetic resonance (MR) imaging is useful to observe the coronal and sagittal images of the brain in order to speculate the etiological mechanism of myelomeningocele and its associated anomalies. We experienced three cases of myelomeningocele and reviewed their MR images using coronal and sagittal tomography in spin echo and inversion recovery technique. The morphological detail of MR images as to the intracranial structures was presented. Possible mechanism of the anomalous structures of the brain in myelomeningocele was also described.