Chudley-McCullough syndrome: bilateral sensorineural deafness, hydrocephalus, and other structural brain abnormalities

The genetic basis of hydrocephalus: genes, pathways, mechanisms, and global impact

Hydrocephalus (HC) is a heterogenous disease characterized by alterations in cerebrospinal fluid (CSF) dynamics that may cause increased intracranial pressure. HC is a component of a wide array of genetic syndromes as well as a secondary consequence of brain injury (intraventricular hemorrhage (IVH), infection, etc.) that can present across the age spectrum, highlighting the phenotypic heterogeneity of the disease. Surgical treatments include ventricular shunting and endoscopic third ventriculostomy with or without choroid plexus cauterization, both of which are prone to failure, and no effective pharmacologic treatments for HC have been developed. Thus, there is an urgent need to understand the genetic architecture and molecular pathogenesis of HC. Without this knowledge, the development of preventive, diagnostic, and therapeutic measures is impeded. However, the genetics of HC is extraordinarily complex, based on studies of varying size, scope, and rigor. This review serves to provide a comprehensive overview of genes, pathways, mechanisms, and global impact of genetics contributing to all etiologies of HC in humans.

Genetic Epidemiology of Hearing Loss in the 22 Arab Countries: A Systematic Review

BACKGROUND

Hearing loss (HL) is a heterogeneous condition that causes partial or complete hearing impairment. Hundreds of variants in more than 60 genes have been reported to be associated with Hereditary HL (HHL). The HHL prevalence is thought to be high in the Arab population; however, the genetic epidemiology of HHL among Arab populations is understudied. This study aimed to systematically analyze the genetic epidemiology of HHL in Arab countries.

METHODS

We searched four literature databases (PubMed, Scopus, Science Direct, and Web of Science) from the time of inception until January 2019 using broad search terms to capture all the reported epidemiological and genetic data related to Arab patients with HHL.

FINDINGS

A total of 2,600 citations were obtained; 96 studies met our inclusion criteria. Our search strategy yielded 121,276 individuals who were tested for HL over 52 years (1966-2018), of whom 8,099 were clinically diagnosed with HL and belonged to 16 Arab countries. A total of 5,394 patients and 61 families with HHL were genotyped, of whom 336 patients and 6 families carried 104 variants in 44 genes and were from 17/22 Arab countries. Of these variants, 72 (in 41 genes) were distinctive to Arab patients. Arab patients manifested distinctive clinical phenotypes. The incidence of HHL in the captured studies ranged from 1.20 to 18 per 1,000 births per year, and the prevalence was the highest in Iraq (76.3%) and the lowest in Jordan (1.5%).

INTERPRETATION

This is the first systematic review to capture the prevalence and spectrum of variants associated with HHL in an Arab population. There appears to be a distinctive clinical picture for Arab patients with HHL, and the range and distribution of variants among Arab patients differ from those noted in other affected ethnic groups.

Prenatal diagnosis of Chudley-McCullough syndrome

Chudley-McCullough syndrome (CMS) is an autosomal-recessive disorder characterized by a complex brain malformation and profound congenital sensorineural hearing loss. Postnatal brain imaging findings include ventriculomegaly, partial agenesis of corpus callosum, inferior cerebellar dysplasia, arachnoid cysts, and malformations of cortical development including frontal subcortical heterotopia and polymicrogyria. Prenatal diagnosis of CMS is important due to the markedly less severe neurodevelopmental prognosis compared to disorders with similar brain imaging findings. We report prenatal imaging features that help distinguish CMS from other disorders, including slit-like frontal horns, agenesis of the corpus callosum, frontal subcortical heterotopia, arachnoid cysts, and cerebellar dysplasia. © 2016 Wiley Periodicals, Inc.

Syndromic deafness-prevalence, distribution and hearing management protocol in Indian scenario

BACKGROUND

The estimated prevalence of Sensory Neural Hearing Loss (SNHL) in patients less than 18 years of age is 6 per 1000. Roughly 50% of cases of congenital SNHL can be linked to a genetic cause, with approximately 30% being syndromic and the remaining 70% being non-syndromic. The term "syndromic" implies the presence of other distinctive clinical features in addition to hearing loss. The aim of our study was to find the distribution of various Syndromic associations in patients with profound deafness, presented at Madras ENT Research foundation, Chennai and to formulate a management protocol for these patients and to discuss in detail about the clinical features of commonly encountered syndromic deafness.

MATERIALS AND METHODS

Our retrospective study was aimed at describing the various Syndromic associations seen in patients with congenital profound deafness. Information was collected from the medical records. At our centre all patients undergo a comprehensive evaluation. The distribution, etiological factors and management protocol for various syndromes are here presented.

RESULTS

Out of 700 patients with congenital profound deafness all patients with Syndromic associations (n = 35) were studied. 5% of profoundly deaf candidates were found to be syndromic. Most common syndrome in our series was found to be congenital rubella syndrome followed by Jervell and Lange-Nielsen syndrome.

CONCLUSION

Congenital deafness is an associated feature of many syndromes. Detailed history taking with comprehensive evaluation is mandatory to rule out the associated syndromes. Diagnosis must be confirm by a genetic study. Multidisciplinary approach is essential for appropriate diagnosis and management.

Periventricular nodular heterotopia, frontonasal encephalocele, corpus callosal dysgenesis and arachnoid cyst: A constellation of abnormalities in a child with epilepsy

A 7-year-old male child presented with poorly controlled generalized tonic-clonic seizures. On examination, he was mentally retarded, deaf and had a swelling at the root on the nose. Computed tomography scan done previously revealed a left temporal arachnoid cyst (AC) due to which he was referred for surgery. However, magnetic resonance imaging revealed a constellation of abnormalities – all of which could be responsible for his seizures. The combination of periventricular nodular heterotopias with encepaholcele is rarely described in the literature, and more infrequently so its combination with AC and callosal dysgenesis – the Chudley-Mccullough syndrome. We describe the case and review relevant literature on this subject.

GPSM2 mutations cause the brain malformations and hearing loss in Chudley-McCullough syndrome

Autosomal-recessive inheritance, severe to profound sensorineural hearing loss, and partial agenesis of the corpus callosum are hallmarks of the clinically well-established Chudley-McCullough syndrome (CMS). Although not always reported in the literature, frontal polymicrogyria and gray matter heterotopia are uniformly present, whereas cerebellar dysplasia, ventriculomegaly, and arachnoid cysts are nearly invariant. Despite these striking brain malformations, individuals with CMS generally do not present with significant neurodevelopmental abnormalities, except for hearing loss. Homozygosity mapping and whole-exome sequencing of DNA from affected individuals in eight families (including the family in the first report of CMS) revealed four molecular variations (two single-base deletions, a nonsense mutation, and a canonical splice-site mutation) in the G protein-signaling modulator 2 gene, GPSM2, that underlie CMS. Mutations in GPSM2 have been previously identified in people with profound congenital nonsyndromic hearing loss (NSHL). Subsequent brain imaging of these individuals revealed frontal polymicrogyria, abnormal corpus callosum, and gray matter heterotopia, consistent with a CMS diagnosis, but no ventriculomegaly. The gene product, GPSM2, is required for orienting the mitotic spindle during cell division in multiple tissues, suggesting that the sensorineural hearing loss and characteristic brain malformations of CMS are due to defects in asymmetric cell divisions during development.

Unique disease heritage of the Dutch-German Mennonite population

The Dutch-German Mennonites are a religious isolate with foundational roots in the 16th century. A tradition of endogamy, large families, detailed genealogical records, and a unique disease history all contribute to making this a valuable population for genetic studies. Such studies in the Dutch-German Mennonite population have already contributed to the identification of the causative genes in several conditions such as the incomplete form of X-linked congenital stationary night blindness (CSNB2; previously iCSNB) and hypophosphatasia (HOPS), as well as the discovery of founder mutations within established disease genes (MYBPC1, CYP17alpha). The Dutch-German Mennonite population provides a strong resource for gene discovery and could lead to the identification of additional disease genes with relevance to the general population. In addition, further research developments should enhance delivery of clinical genetic services to this unique community. In the current review we discuss 31 genetic conditions, including 17 with identified gene mutations, within the Dutch-German Mennonite population.

Sensorineural deafness, hydrocephalus and structural brain abnormalities in two sisters: the Chudley-McCullough syndrome

We describe an Italian family in which two sisters have macrocephaly due to hydrocephalus, and sensorineural hearing loss in addition to other brain abnormalities demonstrated by Magnetic resonance imaging (MRI). The girls, born to healthy non-consanguineous parents, have borderline psychomotor development delay (probably due to hearing defect) and minor dysmorphisms. The clinical picture fits the Chudley-McCullough syndrome, an autosomal recessive condition, to date described in only five families. Our data, in particular the neuroradiological findings, include all brain anomalies variably reported in previous works (hydrocephalus, corpus callosum partial agenesis, interhemispheric cyst, cerebral and cerebellar cortex dysplasia), thus illustrating the full phenotype of the syndrome.

Etiological heterogeneity of familial periventricular heterotopia and hydrocephalus

Periventricular heterotopia (PH) represents a neuronal migration disorder that results in gray matter nodules along the lateral ventricles beneath an otherwise normal appearing cortex. While prior reports have shown that mutations in the filamin A (FLNA) gene can cause X-linked dominant PH, an increasing number of studies suggest the existence of additional PH syndromes. Further classification of these cortical malformation syndromes associated with PH allows for determination of the causal genes. Here we report three familial cases of PH with hydrocephalus. One pedigree has a known FLNA mutation with hydrocephalus occurring in the setting of valproic acid exposure. Another pedigree demonstrated possible linkage to the Xq28 locus including FLNA, although uncharacteristically a male was affected and sequencing of the FLNA gene in this individual revealed no mutation. However, in the third family with an autosomal mode of inheritance, microsatellite analysis ruled out linkage with the FLNA gene. Routine karyotyping and fluorescent in situ hybridization using BAC probes localized to FLNA also showed no evidence of genomic rearrangement. Western blot analysis of one of the affected individuals demonstrated normal expression of the FLNA protein. Lastly, sequencing of greater than 95% of the FLNA gene in an affected member failed to demonstrate a mutation. In conclusion, these findings demonstrate the etiological heterogeneity of PH with hydrocephalus. Furthermore, there likely exists an autosomal PH gene, distinct from the previously described X-linked and autosomal recessive forms. Affected individuals have severe developmental delay and may have radiographic findings of hydrocephalus.

Brothers with Chudley-McCullough syndrome: sensorineural deafness, agenesis of the corpus callosum, and other structural brain abnormalities

We describe two brothers with Chudley-McCullough syndrome who are 5 and 17 years old. They were born to healthy consanguineous parents of Pakistani descent. They had severe sensorineural deafness and neuroimaging showed corpus callosum agenesis and other structural brain abnormalities. The Chudley-McCullough syndrome is an autosomal recessive disorder, first described by Chudley et al. [1997: Am J Med Genet 68:350-356]. The original description of the syndrome includes hydrocephalus due to obstruction of the foramen of Monro and early-onset severe to profound sensorineural deafness. We review the findings in the two patients we describe, four children reported in the literature and two patients reported by Hendriks et al. [1999: Am J Med Genet 86:183-186] with sensorineural deafness, corpus callosum agenesis, and interhemispheric cysts, who may well have Chudley-McCullough syndrome. All patients had sensorineural deafness. The neuroimagings of all eight patients showed colpocephaly, which is most likely caused by corpus callosum agenesis. Three patients had other structural brain abnormalities: cortical dysplasia and gray matter heterotopia. We suggest a revision of the clinical description since the most likely basic developmental defect is corpus callosum agenesis and not foramen of Monro obstruction.

Chudley-McCullough syndrome: expanded phenotype and review of the literature

Chudley-McCullough syndrome is an autosomal recessive condition characterized by profound sensorineural deafness, hydrocephalus secondary to obstruction of the foramen of Monro, and other structural abnormalities of the brain. We describe a family including two brothers and a sister with this condition. Each has profound sensorineural deafness that was either congenital or rapidly progressive in infancy and asymmetric dilatation of the lateral ventricles secondary to obstruction of the foramen of Monro. They also have additional brain abnormalities, including arachnoid cyst, partial agenesis of the corpus callosum, and abnormalities in the migration of cerebellar cells. This report is the fourth description of this condition within four years, suggesting Chudley-McCullough may not be as rare as once assumed. We, therefore, recommend an audiological assessment for all children with hydrocephalus, especially those with obstruction of the foramen of Monro.