Familial and syndromic forms of arachnoid cyst implicate genetic factors in disease pathogenesis

Arachnoid cysts (ACs) are the most common space-occupying lesions in the human brain and present significant challenges for clinical management. While most cases of ACs are sporadic, nearly 40 familial forms have been reported. Moreover, ACs are seen with increased frequency in multiple Mendelian syndromes, including Chudley-McCullough syndrome, acrocallosal syndrome, and autosomal recessive primary ciliary dyskinesia. These findings suggest that genetic factors contribute to AC pathogenesis. However, traditional linkage and segregation approaches have been limited in their ability to identify causative genes for ACs because the disease is genetically heterogeneous and often presents asymptomatically and sporadically. Here, we comprehensively review theories of AC pathogenesis, the genetic evidence for AC formation, and discuss a different approach to AC genomics that could help elucidate this perplexing lesion and shed light on the associated neurodevelopmental phenotypes seen in a significant subset of these patients.

Case report: a novel mutation in ZIC2 in an infant with microcephaly, holoprosencephaly, and arachnoid cyst

RATIONALE

Holoprosencephaly (HPE) is a severe congenital brain malformation resulting from failed or incomplete forebrain division in early pregnancy.

PATIENT CONCERNS

In this study, we reported a 9-month old infant girl with mild microcephaly, semilobor HPE, and arachnoid cyst.

DIAGNOSES

Potential genetic defects were screened directly using trio-case whole exome sequencing (WES) rather than traditional karyotype, microarray, and Sanger sequencing of select genes.

OUTCOMES

A previous unpublished de novo missense mutation (c.1069C >G, p.H357D) in the 3rd zinc finger domain (ZFD3) of the ZIC2 gene was identified in the affected individual, but not in the parents. Sanger sequencing using specific primers verified the mutation. Extensive bioinformatics analysis confirmed the pathogenicity of this extremely rare mutation. Phenotype-genotype analysis revealed significant correlation between the 3rd zinc-finger domain with semilobor HPE.

LESSONS

These findings expanded the spectrum of the ZIC2 gene mutations and associated clinical manifestations, which is the first identification of a mutated ZIC2 gene in a Han infant girl with mild microcephaly, semilobor HPE, and arachnoid cyst.

Familial intracranial arachnoid cysts with a missense mutation (c.2576C > T) in RERE: A case report

RATIONALE

Arachnoid cysts are relatively common intracranial space-occupying lesions; nevertheless, familial intracranial arachnoid cysts are extremely rare, with only a few cases having been reported.

PATIENT CONCERNS

The proband was a 7-year-old girl who had experienced generalized tonic-clonic seizures 5 times in the 8 days prior to admission. Nine months later, her 6-year-old younger female cousin presented to us with a 3-day history of headache.

DIAGNOSES

Brain magnetic resonance imaging (MRI) confirmed the diagnosis of arachnoid cyst for both of the girls.

INTERVENTIONS

A cyst-peritoneal shunting and cyst fenestration were performed for the 7-year-old girl and her cousin separately. Sanger sequencing revealed a heterozygous missense mutation (c.2576C > T) in the Arginine-Glutamic Acid Dipeptide Repeats gene (RERE).

OUTCOMES

The outcome was favorable and the follow-up was uneventful.

LESSONS

We hypothesize that the mutation in RERE may be associated with the pathogenesis of familial intracranial arachnoid cysts.

A screening method to distinguish syndromic from sporadic spinal extradural arachnoid cyst

BACKGROUND

Spinal extradural arachnoid cyst (SEDAC) is a cystic lesion that protrudes into the epidural space from a small dural defect. Early diagnosis of SEDAC is important because its expansion causes neurological damage. Two types of SEDAC, syndromic and sporadic, are present. Syndromic SEDAC is inherited as a part of lymphedema-distichiasis syndrome caused by mutations in the FOXC2 gene; however, it is often mistaken as sporadic because of low penetrance. It is not reasonable to conduct a genetic testing for all SEDAC patients and their family members. The aim of this study is to establish an effective screening method to distinguish syndromic SEDAC from sporadic SEDAC.

METHODS

We performed a retrospective review of medical records and imaging studies of 29 subjects who were diagnosed with SEDAC. Clinical features, family history and magnetic resonance imaging (MRI) were analyzed. Mutations in FOXC2 were examined by Sanger-sequencing of the entire coding region of the genes. SEDAC having a mutation in FOXC2 gene was defined with syndromic SEDAC.

RESULTS

Eleven subjects had a heterozygous mutation in FOXC2. They were all familial and hence syndromic SEDAC. Only one proband had known family history of SEDAC at diagnosis. MRI findings and physical examinations, especially eye and leg examinations, were quite useful to screen syndromic SEDAC. Physical examination often showed accompanying lymphedema and distichiasis in syndromic SEDAC. Syndromic SEDAC tended to have multiple cysts out of the thoracolumbar area.

CONCLUSIONS

We established an effective screening method based on physical examinations and MRI findings.

Outcome of Fetuses with Supratentorial Extra-Axial Intracranial Cysts: A Systematic Review

OBJECTIVE

To investigate the incidence of associated anomalies, aneuploidy, cyst progression, need for surgery and neurodevelopmental outcome in fetuses with extra-axial supratentorial intracranial cysts.

DATA SOURCES

Medline, Embase and CINAHL databases were searched and the following outcomes analyzed: associated central nervous system (CNS) and extra-CNS anomalies detected at the scan, chromosomal anomalies, additional CNS anomalies detected only at prenatal MRI, additional CNS anomalies detected only after birth, cyst progression in utero, neurological outcome and need for surgery. Two authors reviewed all abstracts independently. Results were reported as proportions, and between-study heterogeneity was explored using the I² statistic; fixed or random effect models were used accordingly.

RESULTS

Ten studies involving 47 fetuses were included in the meta-analysis. Arachnoid cysts (n = 24) had associated CNS anomalies and extra-CNS in 73% (95% CI 56-88) and 14% (95% CI 4-29), respectively. The most common associated anomalies were ventriculomegaly and callosal abnormalities. Chromosomal abnormalities were present in 6% (95% CI 0-30), but fetuses with isolated cysts were always euploid (0/7; 95% CI 0-29). Fetal MRI and postnatal examination identified 5 additional cases (21%, 95% CI 1-57). Cavum veli interpositi (CVI) cysts had associated CNS and extra-CNS anomalies in 31% (95% CI 13-52) and 6% (95% CI 0-29), respectively. No chromosomal or callosal anomalies were found in these cases. In isolated CVI cysts, no cases of associated anomalies were detected postnatally. Intrauterine regression occurred in 23% of CVI cysts and in none of the arachnoid cysts. In children with arachnoid cyst, the occurrence of hydrocephaly and mass effect on the adjacent structures were observed in 23.9% (95% CI 8.3-4.4) and 26.8% (95% CI 4.0-60.1), respectively. None of the cases included had abnormal motor outcome or intelligence. The rate of surgery was 34.7% (95% CI 16.0-56.4). None of the children with a prenatal diagnosis of isolated CVI cyst experienced any of the adverse outcomes explored in this review.

CONCLUSIONS

Extra-axial supratentorial cysts diagnosed in utero are frequently associated with other neural and extra-neural anomalies. However, this may represent the consequence of a selection bias. Interhemispheric arachnoid cysts were typically associated with callosal anomalies. Abnormal karyotypes were seen only in fetuses with multiple anomalies. Arachnoid, but not CVI, cysts frequently increased in size throughout gestation.

Identification of HOXD4 Mutations in Spinal Extradural Arachnoid Cyst

Spinal extradural arachnoid cyst (SEDAC) is a cyst in the spinal canal that protrudes into the epidural space from a defect in the dura mater and leads to neurological disturbances. We previously showed that familial SEDAC is caused by FOXC2 mutation; however, the causal gene of sporadic SEDAC has not been identified. To identify the causal gene of sporadic SEDAC, we performed whole exome sequencing for 12 subjects with sporadic SEDAC and identified heterozygous HOXD4 loss-of-function mutations in three subjects. HOXD4 haplo-insufficiency causes SEDAC and a transcriptional network containing HOXD4 and FOXC2 is involved in the development of the dura mater and the etiology of SEDAC.

FOXC2 mutations in familial and sporadic spinal extradural arachnoid cyst

Spinal extradural arachnoid cyst (SEDAC) is a cyst in the spinal canal that protrudes into the epidural space from a defect in the dura mater. Most cases are sporadic; however, three familial SEDAC cases have been reported, suggesting genetic etiological factors. All familial cases are associated with lymphedema-distichiasis syndrome (LDS), whose causal gene is FOXC2. However, FOXC2 mutation analysis has been performed in only 1 family, and no mutation analysis has been performed on sporadic (non-familial) SEDACs. We recruited 17 SEDAC subjects consisting of 2 familial and 7 sporadic cases and examined FOXC2 mutations by Sanger sequencing and structural abnormalities by TaqMan copy number assay. We identified 2 novel FOXC2 mutations in 2 familial cases. Incomplete LDS penetrance was noted in both families. Four subjects presented with SEDACs only. Thus, SEDAC caused by the heterozygous FOXC2 loss-of-function mutation should be considered a feature of LDS, although it often manifests as the sole symptom. Seven sporadic SEDAC subjects had no FOXC2 mutations, no symptoms of LDS, and showed differing clinical characteristics from those who had FOXC2 mutations, suggesting that other gene(s) besides FOXC2 are likely to be involved in SEDAC.

Intracranial arachnoid cyst family with autosomal recessive trait mapped to chromosome 6q22.31-23.2

BACKGROUND

Arachnoid cysts are congenital fluid-filled compartments within the cerebrospinal fluid cisterns and cerebral fissures. They most commonly occur sporadically, and familial occurrence has rarely been reported. In this study, we showed the first genetic linkage in the literature in a pure intracranial arachnoid cyst family with autosomal recessive trait.

METHODS

We identified an intracranial arachnoid cyst family in southern Turkey whose six of seven offspring had intracranial arachnoid cysts in different localizations, and collected venous blood from seven offspring of the family. Whole-genome linkage analysis was performed in all offspring.

RESULTS

A theorical maximum logarithm of the odds score of 4.6 was identified at chromosome 6q22.31-23.2. This result shows strong genetic linkage to this locus.

CONCLUSIONS

We present the first genetic linkage analysis result in a pure intracranial arachnoid cyst family in literature. Further investigation of this linkage area can reveal a causative gene causing the intracranial arachnoid cyst phenotype and can illuminate the pathogenesis of this disease.

A new family with autosomal dominant porencephaly with a novel Col4A1 mutation. Are arachnoid cysts related to Col4A1 mutations?

Porencephaly is an extensively encountered condition in pediatric neurology practice and leads to serious morbidity with its complications. Important etiological factors are trauma, hemorrhage, infection and thrombophilic factors that may cause destruction in the developing brain. Col4A1 mutations were also shown in familial porencephaly cases. We describe two siblings with porencephaly, hemiparesis, epilepsy, atrophic kidney in one of the siblings and asymptomatic mothers with an arachnoid cyst. We performed Col4A1 gene mutation screening and detected a novel mutation in mother and both of the children. This family has some features previously undescribed in patients with mutations of Col4A1 gene like atrophic kidney in one sibling and arachnoid cyst in the mother. We discuss here the possible relationship between these abnormalities and the mutation.

Dubowitz syndrome: a cholesterol metabolism disorder?

Dubowitz syndrome (DS) (MIM#223370) (4) is a very rare genetic and developmental disorder involving multiple congenital anomalies including: 1) growth failure/short stature; 2) unusual but characteristic facial features; small triangular face, high sloping forehead, ptosis, short palpebral fissures, broad and flat nasal bridge; 3) microcephaly; 4) mild mental retardation; and 5) in at least 50% of the cases, eczema. Multiple organ systems are affected and the disorder is unpredictable and extremely variable in its expression. Here we describe a male Turkish patient who has typical and less common findings of DS with additionally persistently low serum lipid levels and an arachnoid cyst. The present patient is the second case of DS with persistently low cholesterol levels.

Apparently novel genetic syndrome of pachygyria, mental retardation, seizure, and arachnoid cysts

We report on an apparently new syndrome in a consanguineous family with seven members, three of whom have cerebral anomalies including pachygyria and arachnoid cysts along with mental retardation and seizures. The two patients with seizure disorders also had multiple enlarged perivascular spaces seen in the white matter of the centrum semiovale. Our data provide a contribution to the accumulating knowledge on familial cerebral anomalies including arachnoid cysts and lissencephaly. Given the lack of mutation in known lissencephaly genes such as LIS1, 14-3-3epsilon, and DCX, this syndrome may constitute a new phenotype with autosomal recessive inheritance.

Multiple extradural arachnoid cysts: report of two operated cousin cases

STUDY DESIGN

Report of 2 operated cousin cases of the multiple spinal extradural arachnoid cysts.

OBJECTIVE

To report the operative findings of cousin cases of the multiple spinal extradural arachnoid cysts and analyze a genetic etiology with the pedigree of all family members.

SUMMARY OF BACKGROUND DATA

Spinal extradural arachnoid cyst is a relatively rare condition that occupies the intraspinal space and sometimes causes neurologic disturbances. The exact etiology is unknown since most reported cases are sporadic. Minimally invasive treatments have been recently applied to a single extradural arachnoid cyst. However, it is still unknown which minimally invasive treatments can be applied to the multiple extradural arachnoid cysts.

METHODS

We experienced 2 cousin cases of multiple spinal extradural arachnoid cysts. Operative findings were described. The pedigree of all family members was made, and a genetic etiology was discussed.

RESULTS

Minimally invasive treatment was tried in Case 1. However, it failed to remove all cysts completely. Each cyst had each stalk communicating with subarachnoid space in both cases. Pedigree showed that the mode of inheritance was likely autosomal dominant.

CONCLUSION

When the cysts are multiple, it is necessary to identify a dural defect in each cyst. The etiology of the multiple extradural arachnoid cysts may be hereditary.

Oculo-ectodermal syndrome: is arachnoid cyst a common finding?

Oculo-ectodermal syndrome is a rare condition characterized by aplasia cutis and epibulbar dermoids. We present the case of a 6-year-old girl with oculo-ectodermal syndrome, who was found to have an arachnoid cyst by head computed tomography. This is the third case of oculo-ectodermal syndrome with arachnoid cyst reported in the literature, and suggests that arachnoid cyst may be a phenotypic feature of oculo-ectodermal syndrome.

Clinical manifestations of chromosome 21 interstitial deletion: report of four cases

Chromosome 21 is the smallest human chromosome; it contains 1.7% of the human genome, or about 54,000 kb. Multiple abnormalities have been observed in patients with a deletion of the long arm of chromosome 21. Phenotypic variability between cases involving different deletions of 21q have been described. We report four cases of deletion (21)(q11.2-q22.1). Three of the reported cases are familial, involving a mother and her two sons, and one is de novo. All cases had mild mental retardation, antimongolian slants, long philtrum, and protruding tongue as well as open mouth. Hypertonia was noted when each was young. Arachnoid cyst, cerebral dysfunction, thalassemia minor, and growth hormone deficiency were found in the de novo case. This is the first report of chromosomal deletion (21)(q11.2-q22.1) in the Taiwanese population.

Familial arachnoid cysts

Arachnoid cysts are a relatively common incidental finding on neuroimaging studies of the brain. Although most cases are sporadic, there have been some reports of arachnoid cysts in several members of the same family. This report describes two additional families with three members affected in each one. Both families had members with arachnoid cysts in two consecutive generations. In one of the families, arachnoid cysts were associated with a deletion in the long arm of chromosome 16, an association not described previously. These descriptions suggest that in some cases arachnoid cysts may have a genetic basis.

A new SPG4 mutation in a variant form of spastic paraplegia with congenital arachnoid cysts

The clinical and genetic findings are described for 16 patients from a large Italian family with a variant form of hereditary spastic paraplegia and congenital arachnoid cysts inherited as an autosomal dominant trait. A molecular study has revealed a novel missense mutation, T614I, in exon 17 of SPG4, which may play a role in both focal cortical dysgenesis and neurodegeneration of the motor neurons in the corticospinal tract.

Familial arachnoid cysts associated with oculopharyngeal muscular dystrophy

Cerebral arachnoid cysts that occur in more than one member of a family have been rarely reported. These familial cases are important because they imply a genetic component in the pathophysiology of these arachnoid cysts. We present an unusual family in which two conditions, a genetic myopathy, oculopharyngeal muscular dystrophy (OPMD), and arachnoid cysts occur together. OPMD is caused by a mutation in the PAPB2 gene that localizes to chromosome 14. In this family, two siblings with genetically confirmed OPMD both have left hemispheric intracranial arachnoid cysts unassociated with other cerebral abnormalities. The association of these two disorders suggests that in this family, a chromosome 14 gene may play a role in the development of arachnoid cysts.

Retrocerebellar arachnoid cysts in siblings with mental retardation and undescended testis

Arachnoid cysts comprise approximately 1% of all intracranial space-occupying lesions and usually occur sporadically. We report retrocerebellar arachnoid cysts in two male siblings with mental retardation and undescended testis, suggesting the possibility of a genetic basis for at least some cases of retrocerebellar arachnoid cysts.

Familial arachnoid cysts in association with autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is a systemic disorder well-known for its association with intracranial aneurysms. Recently, intracranial arachnoid cysts have also been reported to be associated with ADPKD. We describe a father and daughter who each has a posterior fossa arachnoid cyst and asymptomatic ADPKD. To our knowledge, this is the first report of familial occurrence of arachnoid cysts in association with ADPKD.

Chronic subdural hematoma in autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) has been associated with an increased incidence of aneurysmal subarachnoid hemorrhage and intracerebral hematomas. We describe five patients with chronic subdural hematomas, a previously unrecognized complication of ADPKD. In four of the five cases, no trigger was apparent. Clinical presentation was subtle, with mild hemiparesis, headache, or both in four patients and transient neurological deficits mimicking transient ischemic attacks in one patient. In three of the five patients, a retrocerebellar arachnoid cyst was found, suggesting a plausible causal relation between the intracranial arachnoid cysts and the subdural hematomas. In one patient, subdural hematoma was in close proximity to the frontally located arachnoid cyst.

Bilateral sensorineural deafness, partial agenesis of the corpus callosum, and arachnoid cysts in two sisters

We describe two sisters (ages 10 and 3 years, respectively) with a normal development and a combination of congenital sensorineural hearing loss, partial agenesis of the corpus callosum, arachnoid cyst, and hydrocephalus. Neither girl has distinctive physical anomalies. In the oldest girl, there was a hearing loss of 80 dB bilaterally, and the most severe loss on audiogram was seen at 2,000-4,000 Hz. In the youngest girl, there was a hearing loss of 100 dB bilaterally. Above 2,000 Hz no neural reactions were seen. Cerebral magnetic resonance imaging in one girl and computed tomography in the other showed a partial agenesis of the corpus callosum and a cyst in the pineal region, causing an aqueduct stenosis by compression and consequent hydrocephalus. The parents have normal hearing, and brain magnetic resonance imaging showed no abnormalities. They are nonconsanguineous but from the same small village. This is the first report of a combination of congenital sensorineural hearing loss, partial agenesis of the corpus callosum, and an arachnoid cyst. The pattern of inheritance is probably autosomal recessive.

Dominantly inherited cerebral dysplasia: arachnoid cyst associated with mild mental handicap in a mother and her son

We report a mother and son who each presented in infancy with hypotonia and global developmental delay. Subsequently, in both subjects, mild mental handicap was diagnosed in association with temporal lobe arachnoid cysts. Mendelian inheritance of this phenotype seems likely and macroscopic cerebral dysplasia in general may be underdiagnosed in people with familial, mild mental handicap.

Absence/hypoplasia of tibia, polydactyly, retrocerebellar arachnoid cyst, and other anomalies: an autosomal recessive disorder

Absence or hypoplasia of the tibia has been reported to occur as an isolated hereditary malformation as well as a feature of several autosomal recessive and autosomal dominant syndromes. We report three sibs with absence or hypoplasia of the tibia in association with other malformations whose parents are first cousins once removed. These infants appear to have a "new" autosomal recessive syndrome.

Bilateral arachnoid cysts of the sylvian region in female siblings with glutaric aciduria type I. Report of two cases

Two sisters, aged 6 and 2 1/2 years, presented with macrocephaly and delayed motor development and were found on computerized tomography to have bilateral arachnoid cysts of the sylvian region. Cystoperitoneal shunting of the larger cysts resulted in considerable neurological improvement in both children. Subsequent screening of the patients' urine for organic acids showed that the two sisters were suffering from glutaric aciduria type I (GA-I). To the best of the authors' knowledge, this is the first report to provide clear radiological and surgical evidence of the association between GA-I and bilateral arachnoid cysts of the sylvian region. The role of the shunting procedure used in these cases is discussed.

Early prenatal diagnosis of an infratentorial arachnoid cyst: association with an unbalanced translocation

Arachnoid cysts are an uncommon central nervous system malformation, representing only 1 per cent of all intracranial masses. We report the second-trimester prenatal diagnosis of a posterior fossa arachnoid cyst, associated with an unbalanced X;9 translocation.

Familial intracranial arachnoid cysts

Three siblings with intracranial arachnoid cysts are described, two males and one female. One of the males has symmetric, bilateral, temporoparietal convexity cysts, and the others have singular, unilateral cysts. Three additional siblings in the family and other known relatives are clinically unaffected. As far as we know, this is the second reported case of familial intracranial arachnoid cysts and the first involving three siblings. The significance of these cysts and a review of the literature are presented.