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Dandy-Walker malformation (DWM), the most common human cerebellar malformation, has only one characterized associated locus. Here we characterize a second DWM-linked locus on 6p25.3, showing that deletions or duplications encompassing FOXC1 are associated with cerebellar and posterior fossa malformations including cerebellar vermis hypoplasia (CVH), mega-cisterna magna (MCM) and DWM. Foxc1-null mice have embryonic abnormalities of the rhombic lip due to loss of mesenchyme-secreted signaling molecules with subsequent loss of Atoh1 expression in vermis. Foxc1 homozygous hypomorphs have CVH with medial fusion and foliation defects. Human FOXC1 heterozygous mutations are known to affect eye development, causing a spectrum of glaucoma-associated anomalies (Axenfeld-Rieger syndrome, ARS; MIM no. 601631). We report the first brain imaging data from humans with FOXC1 mutations and show that these individuals also have CVH. We conclude that alteration of FOXC1 function alone causes CVH and contributes to MCM and DWM. Our results highlight a previously unrecognized role for mesenchyme-neuroepithelium interactions in the mid-hindbrain during early embryogenesis.

A black and white female German Holstein calf showed a highly deformed cranium. The animal was not able to stand. Further findings were bilateral strabismus divergens and negative pupillary light reflexes. Magnetic resonance imaging and pathological-anatomical examination showed that the cerebrum was replaced to a high degree by the ventricle system filled with 1.5 liters of cerebrospinal fluid. The hemispheres of the cerebellum were ruptured by the dilated fourth ventricle. In addition, the vermis and pons were missing and fluid accumulation in the subarachnoidal space extending up to the first spinal cord segments was visible. Inbreeding was not detected in the 3-generation-pedigree. No other affected calves from the same parents were known at the farm. Chromosomal abnormalities could not be detected after examination of 30 metaphase spreads using a light microscope. Infections and parasitic diseases could be ruled out for this anomaly. Very rare defect alleles might have been involved in the development of these inborn defects.

This article presents a case review of a newborn diagnosed with a complex chromosomal rearrangement, as demonstrated through a painted chromosomal analysis. This infant presented with multiple dysmorphology including cutis aplasia, multiple ocular malformations, bilateral cleft lip and palate, and postnatal hydrocephaly. A chromosomal analysis revealed multiple-ways, balanced translocation involving chromosomes 3, 4, 6, 8, and 9. This case study provides a unique opportunity to, in retrospect, trace each malformation exploring the pathophysiology, etiology, and correlating origin with chromosomal variation. Careful review of this case, enhanced by the visually augmented representation of each translocation, will increase understanding of chromosomal anomalies and their implications in embryological development and clinical presentation.

An 11-month-old girl who has Dandy-Walker's variant (DWV) associated with tetralogy of Fallot (TOF), atrial septal defect (ASD), patent ductus arteriosus (PDA), and primary hypothyroidy is presented. There has been no report describing a case of DWV associated with TOF, ASD and PDA and primary hypothyroidy. The first case of Dandy-Walker malformation associated with TOF was reported by Kohyama et al in 1988, since then, a few cases were reported in the literature. Our patient is the first reported case.

Objective: Keratitis-ichthyosis-deafness syndrome (KID) is a rare congenital disorder. Mutations in the GJB2 gene have recently been identified as the causative mutations of KID., Aim: To define the GJB2 mutation in a Chinese patient with KID and brain malformation., Methods: Genomic DNA was extracted from peripheral blood and used to amplify the GJB2 gene. Direct sequencing and endonuclease digestion were used for mutation analysis., Results: We identified a heterozygous missense mutation (D50N) in the GJB2 gene in this patient., Conclusions: These results indicate that KID syndrome in this patient was caused by a dominant mutation of GJB2.

Background: Hereditary spastic paraparesis (HPS) linked to mutations in the spastin gene (SPG4) is considered to be a pure form of spastic hereditary paraparesis. However, in this disease also other signs of central nervous system involvement are frequently found., Methods: Clinical, genetical and neuroradiological investigations were carried out in a large family with autosomal dominant spastic paraparesis and in a sporadic case with spastic paraparesis., Results: Additional clinical and molecular data are provided, studying other members of the same pedigree, as already described, with a five-base deletion in exon 9 of the SPG4 gene (1215-1219delTATAA) whose members show MRI anomalies that fall within the Dandy-Walker continuum. Furthermore, an unrelated female patient with hypoplasia of the cerebellar vermis is indicated, carrying a de novo previously reported mutation of the SPG4 gene (c.1741C>T p.R581X)., Conclusions: Spastin may play an important role in the development of the central nervous system and in particular in the development of the structures of posterior fossa.

Dandy-Walker malformation is a congenital brain abnormality involving the fourth ventricle and cerebellum. We report on a case of twins discordant for this disorder diagnosed in the second trimester of gestation. The twin pregnancy was revealed to be monozygotic using DNA investigation. To our knowledge, this is the first time monozygotic twins discordant for Dandy-Walker malformation have been described., ((c) 2009 S. Karger AG, Basel.)

Microdeletions of Xp22.3 are associated with contiguous gene syndromes, the extent and nature of which depend on the genes encompassed by the deletion. Common symptoms include ichthyosis, mental retardation and hypogonadism. We report on a boy with short stature, ichthyosis, severe mental retardation, cortical heterotopias and Dandy-Walker malformation. The latter two abnormalities have so far not been reported in terminal Xp deletions. MLPA showed deletion of SHOX and subsequent analysis using FISH and SNP-arrays revealed that the patient had an 8.41 Mb distal deletion of chromosome region Xp22.31 --> Xpter. This interval contains several genes whose deletion can partly explain our patient's phenotype. His cortical heterotopias and DWM suggest that a gene involved in brain development may be in the deleted interval, but we found no immediately obvious candidates. Interestingly, further analysis of the family revealed that the patient had inherited his deletion from his mother, who has a mos 46,X,del(X)(p22)/45,X/46, XX karyotype., ((c) 2008 Wiley-Liss, Inc.)

Objective: To delineate a new syndrome of brain dysgenesis and cutis laxa based on the description of 11 patients belonging to nine unrelated families recruited through an international collaboration effort., Methods: Careful clinical assessment of patients from birth to the age of 23 years with follow-up studies ranging from 3 to 20 years. Biochemical studies of serum proteins glycosylation by isoelectric focusing and capillary zone electrophoresis were performed in 10 patients. Brain MRI studies using conventional methods were analyzed in eight patients., Results: An expanded clinical spectrum of a syndrome comprising facial dysmorphia (enlarged anterior fontanelles, downward slant of palpebral fissures, prominent root of the nose), a connective tissue disorder (inguinal hernia, hip dislocation, high myopia), and neurologic impairment was defined. Early developmental delay was followed by onset of generalized seizures by the end of the first decade and a subsequent neurodegenerative course. A defect of N- or N- plus O-glycosylation of serum transferrins and ApoCIII was observed in 10 patients. An unusual cobblestone-like cortical malformation over the frontal and parietal regions was seen in eight patients and cerebellar abnormalities, including two patients with Dandy-Walker malformation, were observed in three patients., Conclusions: Our results suggest that autosomal recessive cutis laxa, Debré type, initially considered a dermatologic syndrome, is a multisystemic disorder with cobblestone-like brain dysgenesis manifesting as developmental delay and an epileptic neurodegenerative syndrome. It might represent a metabolic cause of Dandy-Walker malformation. It is associated with a deficient N- and-O glycosylation of proteins and shares many similarities with muscle-eye-brain syndromes.

We previously reported a Vietnamese-American family with isolated autosomal dominant occipital cephalocele. Upon further neuroimaging studies, we have recharacterized this condition as autosomal dominant Dandy-Walker with occipital cephalocele (ADDWOC). A similar ADDWOC family from Brazil was also recently described. To determine the genetic etiology of ADDWOC, we performed genome-wide linkage analysis on members of the Vietnamese-American and Brazilian pedigrees. Linkage analysis of the Vietnamese-American family identified the ADDWOC causative locus on chromosome 2q36.1 with a multipoint parametric LOD score of 3.3, while haplotype analysis refined the locus to 1.1 Mb. Sequencing of the five known genes in this locus did not identify any protein-altering mutations. However, a terminal deletion of chromosome 2 in a patient with an isolated case of Dandy-Walker malformation also encompassed the 2q36.1 chromosomal region. The Brazilian pedigree did not show linkage to this 2q36.1 region. Taken together, these results demonstrate a locus for ADDWOC on 2q36.1 and also suggest locus heterogeneity for ADDWOC.

Dandy-Walker syndrome (DWS) is a brain malformation of unknown etiology, but several reports have been published indicating that there is a causal relationship to various types of chromosomal abnormalities and malformation syndromes. In the present article, we present a bibliographical survey of several previously issued reports on chromosomal abnormalities associated with DWS, including our case of DWS found in trisomy 18. There are various types of chromosomal abnormalities associated with DWS; most of them are reported in chromosome 3, 9, 13 and 18. We also summarize some other chromosomal abnormalities and various congenital malformation syndromes.

A 10-year-old boy with vermis hypoplasia, dilatation of the fourth ventricle, enlarged cisterna magna and aplasia of the corpus callosum, consistent with the Dandy-Walker complex (DWC), and slight facial dysmorphisms, severe motor and mental retardation is presented. By combining data obtained by karyotyping, array-CGH, FISH, and multiplex ligation-mediated probe amplification (MLPA) we identified a 5 Mb deletion of the 1q44 --> qter region resulting from a paternal t(1;20)(q44;q13.33). This smallest 1q44 deletion reported so far, enabled us to significantly narrow down the number of candidate genes for the DWC in this region. Since the ZNF124 transcription factor is strongly expressed in the fetal brain it may represent a candidate gene for the DWC at 1q44.

Objective: This study compares the diagnostic accuracy of prenatal ultrasound with postnatal imaging and evaluates for associated fetal anomalies and their impact on immediate neonatal outcome in fetal Dandy Walker complex (DWC)., Methods: Cases of fetal DWC diagnosed in a single ultrasound unit from January 2000 through July 2004 were reviewed for associated fetal anomalies, fetal karyotype, immediate neonatal outcome and postnatal head imaging., Results: A total of 55 fetuses with DWC were identified. Of liveborn cases, postnatal imaging confirmed prenatal intracranial findings in 50% of Dandy Walker variant (DWV) and 100% of Dandy Walker malformation (DWM), with additional central nervous system findings noted in 21% of all cases. Additional fetal anomalies were seen in 26/40 (65%) cases of DWV and 15/15 (100%) cases of DWM. Immediate neonatal survival was predicted by karyotype and associated fetal anomalies., Conclusion: The sonographic diagnosis of fetal DWM is accurate. Significant discrepancies exist in prenatal and postnatal diagnosis of DWV. Comprehensive fetal ultrasound and karyotype should be offered for all fetuses with DWC. Postnatal imaging should be performed on all fetal DWC., (Copyright (c) 2007 S. Karger AG, Basel.)

We report the perinatal findings of a 23 gestational-week fetus with Dandy-Walker malformation (DWM), ventriculomegaly, symmetrical transverse limb deficiencies, hypertelorism, frontal bossing, low-set ears, and a depressed nasal bridge. The karyotype was 46,XX. We believe that this combination is significant. Concomitant DWM and symmetrical distal limb deficiencies may represent a new entity that awaits more new cases for further delineation.

Mice homozygous for the dreher (dr) mutation are characterized by pigmentation and skeletal abnormalities and striking behavioral phenotypes, including ataxia, vestibular deficits, and hyperactivity. The ataxia is associated with a cerebellar malformation that is remarkably similar to human Dandy-Walker malformation. Previously, positional cloning identified mutations in LIM homeobox transcription factor 1 alpha gene (Lmx1a) in three dr alleles. Two of these alleles, however, are extinct and unavailable for further analysis. In this article we report a new spontaneous dr allele and describe the Lmx1a mutations in this and six additional dr alleles. Strikingly, deletion null, missense, and frameshift mutations in these alleles all cause similar cerebellar malformations, suggesting that all dr mutations analyzed to date are null alleles.

Introduction: We report an isolated pedigree in which a consanguineous couple had twin sons with Dandy-Walker malformation (DWM). The mother is similarly affected with the disorder., Discussion: DWM is an abnormality of the central nervous system, which leads to hydrocephalus and is associated with other abnormalities., Conclusion: Inheritance of the disorder remains controversial, with the majority perceived to be sporadic cases. This report suggests an autosomal inheritance.

An 8-year-old boy presenting with hypotonia, moderate mental retardation, developmental delay, and psychomotor retardation is reported. Magnetic resonance imaging of the brain at age 3 years revealed a Dandy-Walker variant. Cytogenetic analysis of the peripheral blood revealed a derivative chromosome 12 with unknown additional material attached to the distal region of the long arm of chromosome 12. The parental karyotypes were normal. Spectral karyotyping (SKY) using the 24-color SKY probes and fluorescence in situ hybridization (FISH) using the specific 7p, 7q, 12p, and 12q telomeric probes confirmed a duplication of distal 7p and a deletion of terminal 12q. The karyotype of the proband was designated as 46,XY.ish der(12)t(7;12) (p21.2;q24. 33)(SKY+, 7pTEL+, 12qTEL-). The present case provides evidence for the association of partial trisomy 7p (7p21.2-->pter) and partial monosomy 12q (12q24.33-->qter) with a cerebellar malformation and the usefulness of SKY and FISH in the identification of a de novo aberrant chromosome resulting from an unbalanced translocation.

We report on a fetus with a large deletion of the distal part of the long arm of chromosome 13, (del(13)(q14 --> qter)) congenital anomalies of the urinary system, lungs and extremities, and Dandy-Walker malformation (DWM). Although DWM has been associated with many chromosomal abnormalities and genetic syndromes, its relation to the distal 13q has been demonstrated recently. In 2002, McCormack et al., described two patients with deletions of the long arm of chromosome 13 who had multiple congenital abnormalities along with holoprosencephaly (HPE) and DWM. The phenotypic features and autopsy findings of a fetus with "distal 13q deletion syndrome" at 22 weeks gestation are discussed and comparison with the previous two cases is made. The findings support the previous hypothesis suggesting that haploinsufficiency at a locus within 13q22-33 due to microdeletions may be responsible for isolated DWM in some of the patients. Detailed examination of 13q (13q22-33) by means of conventional and molecular cytogenetic methods is necessary in cases with DWM., (Copyright 2005 Wiley-Liss, Inc.)

The human ZIC gene family is comprised of five members encoding zinc-finger transcription factors, which are the vertebrate homologs of the Drosophila odd-paired gene. Mutations in ZIC genes in humans have recently been implicated in a wide variety of congenital malformations, including Dandy-Walker malformation, holoprosencephaly, neural tube defects, and heterotaxy. Mutant analysis of these genes in mice has underscored the conserved developmental roles of these genes. Further, this analysis has begun to elucidate the molecular and developmental mechanisms underlying these important birth defects.

5p deletion syndrome commonly known as cri du chat is well described in affected neonates with catlike cry and hypotonia. Karyotyping will usually show a deletion of the short arm of one chromosome 5 with variable breakpoints. Only a few cases have been reported prenatally, and the fetal form of the syndrome has not been clearly individualised. We report a new case of 5p deletion syndrome diagnosed prenatally in association with Dandy-Walker syndrome and agenesis of the corpus callosum. Other brain anomalies have been reported previously, but this unusual association suggests the use of a specific probe in the investigation of these malformations.

Purpose: Ocular anomalies have been associated with numerous chromosomal abnormalities. This report describes partial trisomy 3q in a two-month-old girl with dysmorphic features of the Dup3q phenotype and severe eye and cerebellar malformations., Methods: Clinical examination and chromosomal analysis were conducted., Results: The karyotype of the propositus was 46,XX, ins(3)(pter --> p25::q27 --> q21::p25 --> qter). She had an abnormal head shape, low-set malformed ears, coarse facies, short webbed neck, abnormal foot position, polycystic kidney, and spina bifida. There was also bilateral microphthalmia that was more severe on the right side, microcornea, and corneal opacity. She had posterior fossa abnormalities, including cerebellar vermis hypoplasia suggestive of a Dandy-Walker (DW) malformation., Conclusions: This girl with an intrachromosomal duplication of distal 3q and typical phenotype belongs to the severe end of the spectrum for such cases. The ocular manifestations of the 3q duplication syndrome provide additional evidence of the involvement of developmental eye genes in this chromosomal segment.

Objective: The presentation of sonographic and perinatal findings of tetrasomy 9p., Methods and Results: Chorionic villus sampling and amniocentesis were performed at 19 weeks of gestation because of the sonographic findings of Dandy-Walker malformation with bilateral ventriculomegaly. Cytogenetic analysis showed 47,XX,+i psu dic(9)(pter->q12::q12>-pter). The pregnancy was terminated at 20 weeks of gestation at the request of the parents. At post-mortem examination, the presumed hypoplasia of the vermis could not be confirmed for technical reasons. No other pathological findings were seen., Conclusion: From our experience and from the literature, we conclude that Dandy-Walker malformation is an important finding in tetrasomy 9p. Chromosomal studies should be carried out in fetuses with sonographically detected Dandy-Walker malformation, even in the absence of other abnormalities., (Copyright (c) 2004 John Wiley & Sons, Ltd.)

Dandy-Walker malformation (DWM; OMIM #220200) is a common but poorly understood congenital cerebellar malformation in humans. Through physical mapping of 3q2 interstitial deletions in several individuals with DWM, we defined the first critical region associated with DWM, encompassing two adjacent Zinc finger in cerebellum genes, ZIC1 and ZIC4. Mice with a heterozygous deletion of these two linked genes have a phenotype that closely resembles DWM, providing a mouse model for this malformation.

Objectives: To add to the knowledge of chromosomal abnormalities associated with Dandy-Walker malformation., Methods: Molecular cytogenetic analyses of a chorionic villus sampling and of an amniocentesis of a fetus with Dandy-Walker malformation and abnormal somatic development., Results: All cells examined showed a 47, XY, +idic(9p)(pter-->q12::q12-->pter) de novo karyotype. This report describes the fourth case of a tetrasomy 9p associated with Dandy-Walker malformation., Conclusions: This case, together with the three previously reported cases of an association with a tetrasomy 9p, indicate that this chromosomal aberration should be looked for when Dandy-Walker malformation is detected via prenatal ultrasonography., (Copyright 2004 John Wiley & Sons, Ltd.)

Objective: The purpose of this study was to determine the associated abnormalities and clinical outcomes of fetuses with Dandy-Walker malformations., Methods: Sonograms and medical reports of 78 cases were reviewed and information regarding each outcome was collected from autopsy records, hospital charts and specialists caring for the surviving infants., Results: We identified 64 fetuses with classic Dandy-Walker malformation (DW) and 14 fetuses with Dandy-Walker variant (DWV). A high proportion (44.8%) of the parents were consanguineous. The spectrum and proportion of central nervous system (67.1 vs. 71.4%; p = 1.0) and other malformations (43.7 vs. 64.2%; p = 0.57) associated with DW and DWV were similar. Chromosome abnormalities were found in 9 of the 51 (17.6%) fetuses that underwent karyotype analysis. Only 4 of 64 (6.2%) DW and 3 of 14 (21.4%) DWV infants survived (p 0.14), and all surviving infants with DW or DWV had neurological disorders., Conclusions: DW and DWV cases show so many similarities that a clear-cut distinction is difficult. There was no significant difference in the spectrum of associated anomalies and postnatal prognosis between DW and DWV cases., (Copyright 2004 S. Karger AG, Basel)

We report a 23-week-old male fetus affected by Meckel-Gruber syndrome. Posterior encephalocele, post-axial polydactyly, and Dandy-Walker malformation were observed on ultrasonographic (USG) examination at 22 weeks' gestation, and lobar holoprosencephaly was demonstrated on postmortem magnetic resonance imaging (MRI) prior to autopsy. After the termination of the pregnancy, polycystic dysplastic kidneys were also noted at postmortem investigation. The proband was the product of the fourth pregnancy of a consanguineous family in which all three siblings were also similarly affected. Interestingly, both the two-year-old affected sister and 23-week-old male fetus had Dandy-Walker complex.

From the study of numerical and structural chromosomal abnormalities, there is convincing evidence and accumulating information of a direct karyotype to phenotype correlation. Knowledge of phenotypic consequences of a specific chromosomal imbalance is important for genetic counseling and prenatal diagnosis. However, for unbalanced non-Robertsonian translocations a precise karyotype to phenotype correlation is difficult to predict for several reasons: (I) unbalanced non-Robertsonian translocations are rare, (II) the published case reports are often not age-matched, (III) varying breakpoints result in different lengths of the monosomic and trisomic segments and therefore the phenotype will depend on additional genes present or the loss of coding regions, and (IV) the combination of the same trisomy with different monosomies, or vice versa, can result in diverging phenotypes. Therefore, the study of the karyotype to phenotype correlation in affected relatives of the same age and the identical unbalanced translocation provides a good model to investigate phenotypic consequences of a specific genetic imbalance. We report of two second trimester fetuses with the identical major partial trisomy 9 (9pter-9q22.2) and minor partial trisomy 7 (q35-qter) resulting from a familial translocation (7;9)(q35;q22.2)mat. One fetus presented with a Dandy-Walker malformation, polymicrogyria, and mild dysmorphic features, whereas the other fetus showed unilateral cleft lip and palate without cerebral anomalies. Potential mechanisms for this different phenotypic expression of the same unbalanced translocation resulting in partial trisomy 9 and 7 in the two cousins and possible consequences for genetic counseling and prenatal diagnosis are discussed., (Copyright 2003 Wiley-Liss, Inc.)

Thromboembolic events in neonates are very rare. They are often associated with severe disease affecting the newborn or are secondary to central venous lines or arterial catheters. Most of the described cases of thromboses of the iliac or femoral arteries are associated with cardiac catheterisation or femoral invasive blood pressure monitoring. The relationship between single umbilical arteries and an increased incidence of structural and chromosomal anomalies is well known, but a higher rate of thromboembolic disease in infants with single umbilical arteries has not been described. Rt-PA (recombinant tissue plasminogen activator) has been successfully used in small studies and numerous case reports. To date controlled clinical trials giving guidelines for antithrombotic therapy using rt-PA are still lacking. We report the clinical course of a 700 g premature male, who was born by Caesarean section at 29 + 6 gestational weeks. On the fifth day the baby suffered from arterial thrombosis of the right pelvis axis. Antenatally a single umbilical artery was identified. Iliac arteries on the involved site appeared hypoplastic. Additionally, the prothrombin G20210A mutation was found. The patient was treated successfully using recombinant tissue plasminogen activator. In the case of a high risk of limb or organ loss due to arterial thrombosis, thrombolysis using rt-PA is justified. Appropriate rt-PA treatment has been studied for the adult but not the paediatric population. Hence, well-designed clinical trials are necessary to determine the pharmacokinetics and dynamics of thrombolytic agents in children.

Although a great deal of interest in the genetics and etiology of cerebral, particularly forebrain, malformations has been generated in the past decade, relatively little is known about the basis of congenital malformations of the structures of the posterior fossa, namely the midbrain, cerebellum, pons, and medulla. In this review, we present a classification scheme for malformations of the midbrain and hindbrain based on their embryologic derivation, highlight four of the conditions associated with such abnormalities, and describe the genetics, prognosis, and recurrence risks for each. We describe several disorders in addition to Joubert syndrome with the distinctive radiologic sign known as the "molar tooth sign," comprised of midbrain and hindbrain malformations. We discuss Dandy-Walker malformation, its classical definition, and the surprisingly good outcome in the absence of other brain malformations. We consider the heterogeneous entity of cerebellar vermis hypoplasia and describe the recently identified gene associated with an X-linked form of this condition. Finally, the pontocerebellar hypoplasias are discussed in the context of their generally progressive degenerative and severe course, and the differential diagnosis is emphasized. We anticipate that as imaging technologies improve, differentiation of the various disorders should aid in efforts to identify the causative genes.

Unlabelled: We report on a 17-y-old girl with inherited cutis laxa, immunodeficiency and Dandy-Walker syndrome. Immunodeficiency manifested itself by decreased and fluctuating levels of IgG, IgA and IgM and intermittent leucopenia causing increased susceptibility to respiratory tract infections. Dandy-Walker syndrome (agenesis of the cerebellar vermis with a large posterior fossa cyst communicating with an enlarged 4th ventricle) was shown on a CT scan but with the exception of macrocrania, no typical signs or symptoms were observed at the age of 17. Loose hyperextensible skin with pendulous skinfolds as a manifestation of cutis laxa was observed from birth. Anomalies of the right pulmonary artery, abnormal branching of the left arteria subclavia (arteria lusoria) from the left aortic arch and bicuspidal aortic valve were also present., Conclusion: The combination of the rare disorders cutis laxa, Dandy-Walker syndrome and immunodeficiency is reported here for the first time.

Two patients with partial deletions of the long arm of chromosome 13, del(13)(13q21-q34) and del(13)(13q22-q33), respectively, multiple congenital anomalies including holoprosencephaly (HPE) and the Dandy-Walker malformation (DWM) are described. The occurrence of HPE and the DWM in both of these patients suggests that, in addition to ZIC2, which is important for normal development of the forebrain, there is at least one other dosage-sensitive gene in 13q22-q33 that plays an important role in brain development. The DWM is anatomically and developmentally distinct from HPE. The presence of a DWM in each of these two patients with partial deletions of the long arm of chromosome 13 suggests that haploinsufficiency at a locus in 13q22-q33 may cause this anomaly. These findings suggest that microdeletions in 13q22-q33 may be found in a proportion of patients with an apparently isolated DWM. Therefore, careful high-resolution cytogenetic analysis (550 band level or greater) of 13q22-q33 may be considered in these patients. Furthermore, future molecular studies of this region may reveal candidate gene loci for the DWM.

An infant with Dandy-Walker malformation and prenatally diagnosed tetrasomy 9p is reported. Chromosomal analysis of primary amniocyte culture revealed true mosaicism for two cell lines: 50% of the cells had an isochromosome 9p (pter-q13::q13-pter), and the other 50% showed a normal female karyotype (46,XX). After birth the same chromosomal abnormality was found in 75% of peripheral blood lymphocytes. Phenotypic features included intrauterine growth retardation, hypotrophy of the left side of the body with left microphthalmus, and progressive hydrocephalus secondary to Dandy-Walker malformation. Although most cases of Dandy-Walker malformation are not associated with chromosomal abnormalities, our case, together with two previously reported cases of the same association, indicates that this chromosomal disorder should be looked for in children with Dandy-Walker malformation and abnormal somatic development.

Posterior fossa malformations are a special group of central nervous system anomalies that present during infancy with hypotonia, developmental delay, microcephaly, or hydrocephalus. Recent discoveries of the genetic and epigenetic factors that control hindbrain ontogenesis explain some of these disturbances in cerebellar development. A comprehensive classification of posterior fossa malformations is proposed with particular attention to Dandy-Walker malformation, Joubert syndrome, and other cerebellar hypoplasias. A rare form of cerebellar hypertrophy which caused repeated obstruction at the foramen magnum is recognized. The importance of the cerebellum in language, cognition, and brain growth is stressed.

Objectives: To present the prenatal diagnosis and perinatal findings of partial trisomy 9p and distal 12p deletion., Methods and Results: Amniocentesis was performed at 17 gestational weeks due to a balanced reciprocal translocation t(9;12)(p11.2;p13.3) in the mother. The father's karyotype was normal. The family had a 5-year-old daughter with a Dandy-Walker malformation and a trisomy 9p syndrome. Cytogenetic analysis of the cultured amniotic fluid cells revealed a 46,XY,der(12)t(9;12)(p11.2;p13.3)mat karyotype with partial monosomy 12p(12pter-->p13.3) and partial trisomy 9p(9pter-->p11.2). Sonographic examination of the fetal brain and skull showed bilateral ventriculomegaly, brachycephaly and a Dandy-Walker malformation with an enlarged cisterna magna and absence of the cerebellar vermis. The pregnancy was terminated subsequently. At autopsy, the proband manifested agenesis of the cerebellar vermis and a typical trisomy 9p phenotype., Conclusion: Fetuses with partial trisomy 9p(9pter-->p11.2) may present a Dandy-Walker malformation and ventriculomegaly on prenatal ultrasound in the second trimester. A dosage effect of genes located on 9pter-->p11.2 may be associated with the abnormal development of the central nervous system in patients with partial or complete trisomy 9., (Copyright 2002 John Wiley & Sons, Ltd.)

Two patients with partial deletions of the long arm of chromosome 13, del(13)(13q21-q34) and del(13)(13q22-q33), respectively, multiple congenital anomalies including holoprosencephaly (HPE) and the Dandy-Walker malformation (DWM) are described. The occurrence of HPE and the DWM in both of these patients suggests that, in addition to ZIC2, which is important for normal development of the forebrain, there is at least one other dosage-sensitive gene in 13q22-q33 that plays an important role in brain development. The DWM is anatomically and developmentally distinct from HPE. The presence of a DWM in each of these two patients with partial deletions of the long arm of chromosome 13 suggests that haploinsufficiency at a locus in 13q22-q33 may cause this anomaly. These findings suggest that microdeletions in 13q22-q33 may be found in a proportion of patients with an apparently isolated DWM. Therefore, careful high-resolution cytogenetic analysis (550 band level or greater) of 13q22-q33 may be considered in these patients. Furthermore, future molecular studies of this region may reveal candidate gene loci for the DWM., (Copyright 2002 Wiley-Liss, Inc.)

Fetal triploidy is a frequent reason for early abortion, and only few fetuses survive into the second trimester of pregnancy. Common sonographic markers for triploidy in the second trimester are severe asymmetric growth restriction (triploidy of maternal origin) and partial molar changes of the placenta (triploidy of paternal origin), together with structural fetal malformations. We report prenatal sonographic findings of thirteen triploid fetuses between 18 and 34 weeks' gestational age (eleven fetuses with 69, XXX, and two fetuses with 69, XXY). Intrauterine growth restriction (11/13 fetuses), oligohydramnios (8/13), bilateral cerebral ventriculomegaly (6/13), structural heart defects (4/13), and Dandy-Walker malformation or Dandy-Walker variant (4/13) were the most frequent findings. We conclude that the Dandy-Walker malformation and Dandy-Walker variant should be considered as additional sonographic markers for fetal triploidy.

We report a family in which two sisters had three male fetuses with isolated Dandy-Walker variant (DWV) diagnosed on antenatal ultrasound. DWV is one part of a spectrum of abnormalities related to Dandy-Walker malformation (DWM) which commonly occur in association with other anomalies with or without chromosome abnormalities. The majority of cases are sporadic but rare reports of recurrence in siblings exist. This is the second report suggesting that isolated DWM/DWV can be inherited as an X-linked recessive trait.

A severe form of autosomal recessive osteopetrosis associated with Dandy-Walker syndrome and agenesis of the corpus callosum is reported in a full-term boy born to consanguineous parents. The diagnosis was made shortly after birth. Clinical features were cranio-facial dysmorphy, macrocephaly, hepatosplenomegaly, severe anemia and thrombocytopenia. Skeletal radiographs revealed generalized increase in bone density and abnormal metaphyseal remodeling. Cranial ultrasonogram and computed tomography scan showed Dandy-Walker syndrome, agenesis of corpus callosum and hydrocephalus. The patient rapidly developed severe medullary deficiency and a severe pulmonary infection. He died at the age of 2 months. This association seems extremely rare and was not previously reported in the literature.