Hallux duplication, postaxial polydactyly, absence of the corpus callosum, severe mental retardation, and additional anomalies in two unrelated patients: a new syndrome

Involvement of kinesins in skeletal dysplasia: a review

Skeletal dysplasias are group of rare genetic diseases resulting from mutations in genes encoding structural proteins of the cartilage extracellular matrix (ECM), signaling molecules, transcription factors, epigenetic modifiers, and several intracellular proteins. Cell division, organelle maintenance, and intracellular transport are all orchestrated by the cytoskeleton-associated proteins, and intracellular processes affected through microtubule-associated movement are important for the function of skeletal cells. Among microtubule-associated motor proteins, kinesins in particular have been shown to play a key role in cell cycle dynamics, including chromosome segregation, mitotic spindle formation, and ciliogenesis, in addition to cargo trafficking, receptor recycling, and endocytosis. Recent studies highlight the fundamental role of kinesins in embryonic development and morphogenesis and have shown that mutations in kinesin genes lead to several skeletal dysplasias. However, many questions concerning the specific functions of kinesins and their adaptor molecules as well as specific molecular mechanisms in which the kinesin proteins are involved during skeletal development remain unanswered. Here we present a review of the skeletal dysplasias resulting from defects in kinesins and discuss the involvement of kinesin proteins in the molecular mechanisms that are active during skeletal development.

KIF16B is a candidate gene for a novel autosomal-recessive intellectual disability syndrome

Intellectual disability (ID) and global developmental delay are closely related; the latter is reserved for children under the age of 5 years as it is challenging to reliably assess clinical severity in this population. ID is a common condition, with up to 1%-3% of the population being affected and leading to a huge social and economic impact. ID is attributed to genetic abnormalities most of the time; however, the exact role of genetic involvement in ID is yet to be determined. Whole exome sequencing (WES) has gained popularity in the workup for ID, and multiple studies have been published examining the diagnostic yield in identification of the disease-causing variant (16%-55%), with the genetic involvement increasing as intelligence quotient decreases. WES has also accelerated novel disease gene discovery in this field. We identified a novel biallelic variant in the KIF16B gene (NM_024704.4:c.3611T > G) in two brothers that may be the cause of their phenotype.

Clinical and experimental evidence suggest a link between KIF7 and C5orf42-related ciliopathies through Sonic Hedgehog signaling

Acrocallosal syndrome (ACLS) is an autosomal recessive neurodevelopmental disorder caused by KIF7 defects and belongs to the heterogeneous group of ciliopathies related to Joubert syndrome (JBTS). While ACLS is characterized by macrocephaly, prominent forehead, depressed nasal bridge, and hypertelorism, facial dysmorphism has not been emphasized in JBTS cohorts with molecular diagnosis. To evaluate the specificity and etiology of ACLS craniofacial features, we performed whole exome or targeted Sanger sequencing in patients with the aforementioned overlapping craniofacial appearance but variable additional ciliopathy features followed by functional studies. We found (likely) pathogenic variants of KIF7 in 5 out of 9 families, including the original ACLS patients, and delineated 1000 to 4000-year-old Swiss founder alleles. Three of the remaining families had (likely) pathogenic variants in the JBTS gene C5orf42, and one patient had a novel de novo frameshift variant in SHH known to cause autosomal dominant holoprosencephaly. In accordance with the patients' craniofacial anomalies, we showed facial midline widening after silencing of C5orf42 in chicken embryos. We further supported the link between KIF7, SHH, and C5orf42 by demonstrating abnormal primary cilia and diminished response to a SHH agonist in fibroblasts of C5orf42-mutated patients, as well as axonal pathfinding errors in C5orf42-silenced chicken embryos similar to those observed after perturbation of Shh signaling. Our findings, therefore, suggest that beside the neurodevelopmental features, macrocephaly and facial widening are likely more general signs of disturbed SHH signaling. Nevertheless, long-term follow-up revealed that C5orf42-mutated patients showed catch-up development and fainting of facial features contrary to KIF7-mutated patients.

Novel KIF7 Mutation in a Tunisian Boy with Acrocallosal Syndrome: Case Report and Review of the Literature

Acrocallosal syndrome (ACLS) is a rare autosomal recessive disorder characterized by agenesis of the corpus callosum, facial dysmorphism, postaxial polydactyly of the hands as well as preaxial polydactyly of the feet, and developmental delay. Mutations in the KIF7 gene, encoding a molecule within the Sonic hedgehog (SHH) pathway, have been identified as causative for ACLS but also for the fatal hydrolethalus syndrome and some cases of Joubert syndrome. We report here on a Tunisian boy who shows the clinical characteristics of ACLS and was found to have a novel homozygous KIF7 nonsense mutation. Further, we summarize the current knowledge about the clinical spectrum associated with KIF7 mutations as well as genetic and/or phenotypic overlap with ciliopathies and other mutations in the SHH pathway.

The many faces of KIF7

Mutations in KIF7, the gene that encodes a component of the kinesin complex of anterograde intraflagellar transport in the cilia, have been reported to cause a range of phenotypes including hydrolethalis, acrocallosal syndrome and Joubert syndrome. In a cohort of patients with various neurogenetic phenotypes, we identified novel KIF7 mutations in two families that span the known phenotypic spectrum of KIF7-related disorders. Surprisingly, we also identified a novel truncating KIF7 mutation in a third consanguineous family, in which the index presented with intellectual disability but no overt signs of ciliopathy, and his brain magnetic resonance imaging revealed an isolated dysgenesis of corpus callosum. This small cohort contributes novel pathogenic alleles of KIF7 and suggests that KIF7-related phenotypes can include isolated dysgenesis of corpus callosum with intellectual disability, thus expanding the range of phenotypes that warrant sequencing of this gene.

A mutation in KIF7 is responsible for the autosomal recessive syndrome of macrocephaly, multiple epiphyseal dysplasia and distinctive facial appearance

Background

We previously reported the existence of a unique autosomal recessive syndrome consisting of macrocephaly, multiple epiphyseal dysplasia and distinctive facial appearance mapping to chromosome 15q26.

Methods

In this manuscript, we have used whole exome sequencing on two affected members of a consanguineous family with this condition and carried out detailed bioinformatics analysis to elucidate the causative mutation.

Results

Our analysis resulted in the identification of a homozygous p.N1060S missense mutation in a highly conserved residue in KIF7, a regulator of Hedgehog signaling that has been recently found to be causing Joubert syndrome, fetal hydrolethalus and acrocallosal syndromes. The phenotype in our patients partially overlaps with the phenotypes associated with those syndromes but they also exhibit some distinctive features including multiple epiphyseal dysplasia.

Conclusions

We report the first missense homozygous disease-causing mutation in KIF7 and expand the clinical spectrum associated with mutations in this gene to include multiple epiphyseal dysplasia. The missense nature of the mutation might account for the unique presentation in our patients.

KIF7 mutations cause fetal hydrolethalus and acrocallosal syndromes

KIF7, the human ortholog of Drosophila Costal2, is a key component of the Hedgehog signaling pathway. Here we report mutations in KIF7 in individuals with hydrolethalus and acrocallosal syndromes, two multiple malformation disorders with overlapping features that include polydactyly, brain abnormalities and cleft palate. Consistent with a role of KIF7 in Hedgehog signaling, we show deregulation of most GLI transcription factor targets and impaired GLI3 processing in tissues from individuals with KIF7 mutations. KIF7 is also a likely contributor of alleles across the ciliopathy spectrum, as sequencing of a diverse cohort identified several missense mutations detrimental to protein function. In addition, in vivo genetic interaction studies indicated that knockdown of KIF7 could exacerbate the phenotype induced by knockdown of other ciliopathy transcripts. Our data show the role of KIF7 in human primary cilia, especially in the Hedgehog pathway through the regulation of GLI targets, and expand the clinical spectrum of ciliopathies.

Hirschsprung's disease, acrocallosal syndrome, and congenital hydrocephalus: report of 2 patients and literature review

The L1 cell adhesion molecule (L1CAM) protein is found primarily in the nervous system and is important in neuronal adhesion, migration, neurite outgrowth, and myelination. It is extremely rare that Hirschsprung's disease (HSCR) merges with a disorder showing abnormality of the L1CAM genes such as acrocallosal syndrome (ACS) or X-linked hydrocephalus (XLH). Herein, we report 2 cases--the first showed abnormality of the L1CAM genes and developed HSCR; and the second, with clinically suspected XLH, was successfully operated on for HSCR. When a patient with ACS or XLH presents with constipation, we must consider HSCR in the differential diagnosis, and early treatment is important. Furthermore, it is desirable to select a line treatment of HSCR to prevent infection of the ventriculoperitoneal shunt if the patient requires it.

Holoprosencephaly: clinical, anatomic, and molecular dimensions

Holoprosencephaly is addressed under the following headings: alobar, semilobar, and lobar holoprosencephaly; arrhinencephaly; agenesis of the corpus callosum; pituitary abnormalities; hindbrain abnormalities; syntelencephaly; aprosencephaly/atelencephaly; neural tube defects; facial anomalies; median cleft lip; minor facial anomalies; single maxillary central incisor; holoprosencephaly-like phenotype; epidemiology; genetic causes of holoprosencephaly; teratogenic causes of holoprosencephaly; SHH mutations; ZIC2 mutations; SIX3 mutations; TGIF mutations; PTCH mutations; GLI2 mutations; FAST1 mutations; TDGF1 mutations; and DHCR7 mutations.

A case of schizophrenia with complete agenesis of the corpus callosum

OBJECTIVE

To describe the case of a person with schizophrenia and agenesis of the corpus callosum.

CONCLUSION

A 24-year-old Caucasian woman with schizophrenia was incidentally found to have complete agenesis of the corpus callosum. A comprehensive neuropsychiatric assessment allowed management to be specifically tailored to the patient's unique clinical profile.

Schinzel acrocallosal syndrome

Acrocallosal syndrome (ACLS), also known by its synonyms: Schinzel Acrocallosal syndrome and Hallux duplication, Postaxial polydactyly and absence of corpus callosum, is a rare genetic disorder that is apparent at birth. Although autosomal recessive inheritence has been suggested, ACLS often appears to occur sporadically. Typical characteristics of ACLS are hypoplasia/agenesis of corpus callosum, moderate to severe mental retardation, characteristic craniofacial abnormalities, distinctive digital malformations and growth retardation. It has not been reported from India so far. This article reports a 5-month-old boy with combination of abnormalities consistent with acrocallosal syndrome.

Spectrum of the acrocallosal syndrome

Acrocallosal syndrome (ACS) is an autosomal recessive condition, characterized by agenesis of the corpus callosum, pre- and postaxial polydactyly, minor craniofacial anomalies, and, in most patients, severe psychomotor retardation. We here report on three patients with ACS demonstrating a spectrum from mild to severe involvement. Two patients had only mild to moderate mental retardation at the age of 2(1/2) and 4 years, respectively, with surprisingly good speech development. The third patient was severely affected and died at age 7 days because of persistent apnea. All three patients had agenesis of the corpus callosum, and large intracranial cysts, which in the third case was confirmed as a large arachnoid cyst at autopsy. Cranial cysts were also seen in 10/34 published cases of ACS. Thus, intracerebral cysts are a common finding in ACS and may serve in differentiating ACS from Greig cephalopolysyndactyly syndrome.

Sibs with anencephaly, anophthalmia, clefts, omphalocele, and polydactyly: hydrolethalus or acrocallosal syndrome?

Major characteristics of the acrocallosal syndrome include severe mental retardation, agenesis or hypoplasia of the corpus callosum, and polydactyly of fingers and toes. In the past few years, anencephaly has also been noted, together with other midline defects. We report on a nonconsanguineous, Norwegian couple with a history of two pregnancies with a male and a female fetus, respectively, with anencephaly, median cleft lip and palate, omphalocele, and preaxial polydactyly, suggesting the diagnosis of the acrocallosal syndrome. Both fetuses also lacked eyes and nose, a finding not previously reported in the acrocallosal syndrome. Microphthalmia has been reported in the hydrolethalus syndrome, which may be caused by mutations in the same gene as the acrocallosal syndrome. The present report adds support to the hypothesis that the acrocallosal and hydrolethalus syndromes may be allelic conditions. The family history is consistent with autosomal recessive inheritance.

Acrocallosal syndrome in an Algerian boy born to consanguineous parents: review of the literature and further delineation of the syndrome

We present a 17-month-old boy with the acrocallosal syndrome. He was born to consanguineous parents. Abnormal findings included agenesis of the corpus callosum, a ventricular septal defect (VSD), postaxial polydactyly of fingers, cleft soft palate, intestinal malrotation, large anterior fontanelle, prominent forehead, hypertelorism, epicanthic folds, short nose and mandible and preauricular skin tags, mixed hearing loss, laryngomalacia, and growth and severe motor and mental retardation. A review of previous reports on the acrocallosal syndrome shows considerable clinical variability; minimal diagnostic criteria are proposed. A developmental field defect with disturbance of midline development is suggested.

Assessment and management of fetal agenesis of the corpus callosum

Prenatal counselling for fetal agenesis of the corpus callosum is difficult as the prognosis until now has been so uncertain. We have reviewed the current world English literature to provide the best probabilistic information for prospective parents. In total, there are 70 cases where the diagnosis was made prenatally. The diagnosis of apparently isolated agenesis of the corpus callosum (in the absence of other sonographically detectable anomalies) appears to carry an excellent prognosis, with an 85 per cent chance of a normal developmental outcome and a 15 per cent risk of handicap. Fetal karyotyping is recommended as there is a 1 in 10 risk of aneuploidy. If other anomalies are detected prenatally, the outcome is very poor. Termination of pregnancy is advised in these circumstances.

Molecular genetic approaches to the study of human craniofacial dysmorphologies

Craniofacial dysmorphologies are common, ranging from simple facial disfigurement to complex malformations involving the whole head. With the advent of gene mapping and cloning techniques, the genetic element of both simple and complex human craniofacial dysmorphologies can be investigated. For many of the dysmorphic syndromes, it is possible to find families that display a particular phenotype in either an autosomal dominant, recessive, or X-linked manner. This article focuses on a subgroup of craniofacial dysmorphologies, covering these three main inheritance patterns, that are being studied using molecular biology techniques: DiGeorge syndrome, Treacher Collins syndrome, Greig cephalopolysyndactyly syndrome, acrocallosal syndrome, amelogenesis imperfecta, and X-linked cleft palate with ankyloglossia. Once the mutated or deleted gene or genes for each syndrome have been cloned, patterns of normal and abnormal craniofacial development should be elucidated. This should enhance both diagnosis and treatment of these common and disfiguring disorders.

Agenesis of corpus callosum and dementia of the Alzheimer's type: a review and case report

This paper describes a previously sufficiently functioning 57 year old man who presented with a recent onset of frontal behaviour. Partial agenesis of corpus callosum was an incidental finding on a computerized tomography scan. The EEG was within normal limits and neuropsychological testing did not reveal any interhemispheric disconnection. A SPECT-Scan revealed bilateral hypoperfusion, consistent with Alzheimer's dementia. Normal functioning up to 50 years of age and a later manifestation of Alzheimer's disease along with agenesis of carpus callosum is of clinical interest as such an association has not been published.

Acrocallosal syndrome in two African brothers born to consanguineous parents

We describe two mentally retarded brothers with craniofacial anomalies, polydactyly, and other clinical manifestations compatible with the acrocallosal syndrome (ACS). These are the first black patients from Africa with this diagnosis. They are also the fourth set of sibs described with ACS, and together with the parental consanguinity documented in this family, confirm autosomal recessive inheritance of this syndrome. The clinical manifestations in our patients confirm the intrafamilial variability of the syndrome. Postnatal onset of growth retardation is proposed as an additional manifestation of ACS.

Fronto-nasal dysostosis, callosal agenesis, crossed-fused ectopia, tibial hemimelia, and preaxial polydactyly of feet: severe expression of the acrocallosal syndrome?

We report on a girl with frontonasal "dysostosis," callosal agenesis, crossed-fused ectopia, tibial hemimelia, and preaxial polydactyly of feet. This pattern of the developmental defects suggests a severe form of the acrocallosal syndrome. Implications for genetic counselling are discussed.

X-linked recessive inheritance of dysgenesis of corpus callosum in a Chinese family

This report describes a new syndrome of dysgenesis of corpus callosum with other anomalies, presenting as microcephaly, mental retardation, spasticity, and unusual facial appearance in 2 Chinese brothers and their maternal cousins. To date, there has not been any case reported in the Chinese population of this syndrome. All 4 patients in this report present with the same unusual face. Hydrocephalus and/or interhemispheric cyst were found among them. This syndrome is transmitted as an X-linked trait. The nosology is reviewed and discussed.

Acrocallosal syndrome: report of a Brazilian girl

We report on a Brazilian girl born to nonconsanguineous parents and presenting with frontonasal dysostosis, callosal agenesis, abnormal upper lids, cleft lip/palate, redundant skin in the neck, grooved chin, and bifid thumbs. Major diagnostic criteria present in this patient are related to the acrocallosal syndrome. The clinical and major nosologic aspects of this condition are discussed.

A family with one child with acrocallosal syndrome, one child with anencephaly-polydactyly, and parental consanguinity

A 2-year-old boy with typical features of the acrocallosal syndrome is presented. His parents are first degree cousins and their first pregnancy resulted in spontaneous abortion whereas the offspring of their second pregnancy was an anencephalic baby with bilateral post-axial polydactyly of the hands. The possibility of including anencephaly in the spectrum of the CNS malformations of the acrocallosal syndrome is suggested.

Extending the Pallister-Hall syndrome to include other central nervous system malformations

Hall-Pallister syndrome is defined by specific facial anomalies, post axial polydactyly, imperforate anus, and brain anomalies including a rare diencephalic mass, hypothalamic hamartoblastoma. In this article, two patients are described with the usual features of Hall-Pallister syndrome, including diencephalic anomalies, but without hamartoblastomas. These patients may suggest an appropriate extension of the definition of the Hall-Pallister syndrome.

Further delineation of the acrocallosal syndrome

The acrocallosal syndrome (ACS) was recognized by Schinzel in 1979 as a specific entity, characterized by the association of craniofacial anomalies, total or partial agenesis of corpus callosum, polysyndactyly and mental retardation. The inheritance is autosomal recessive, based on instances of recurrence in siblings and cousins and parental consanguinity. A large inbred kindred with recurrent ACS is presented. This family further strengthens the hypothesis of autosomal recessive inheritance for this syndrome. The array of clinical manifestations in this sibship and those previously reported exemplify the phenomenon of inter- and intrafamilial variability that must be considered when defining ACS. Based on a review of published reports and the present family, essential, additional and occasional findings are distinguished. Attention is drawn to geographical clustering of the families.

Holoprosencephaly-polydactyly ('pseudotrisomy 13') syndrome: a syndrome with features of hydrolethalus and Smith-Lemli-Opitz syndromes. A collaborative multicentre study

A syndrome of holoprosencephaly and postaxial polydactyly, associated with hydrocephalus, heart defect, adrenal hypoplasia, and other visceral malformations, has been observed in five unrelated children with normal chromosomes. Clinical overlap with lethal acrodysgenital dwarfism (Smith-Lemli-Opitz syndrome type II) and hydrolethalus syndrome is discussed. Recessive inheritance seems likely.

How wide is the clinical spectrum of the acrocallosal syndrome? Report of a mild case

A boy presenting with an incomplete form of the acrocallosal syndrome is described. The syndrome shows clinical variability and it is stressed that none of the components is constant and facial dysmorphism is not always characteristic.

Acrocallosal syndrome

Acrocallosal syndrome is an autosomal recessive disorder of brain malformation and complex polydactyly. We report on an additional patient with this disorder. It is suggested that increased birth weight and cerebellar hypoplasia occur in acrocallosal syndrome. The finding of an extra bone within the anterior fontanel in our patient suggests similarity to the Xt mouse mutant, which is homologous to Greig syndrome in man. This provides additional support for the hypothesis of allelism of the Greig and acrocallosal syndromes.

The acrocallosal syndrome in a Turkish boy

A 6 month old Turkish boy with the acrocallosal syndrome is reported. The patient, born to consanguineous, healthy parents, presented with macrocephaly, a prominent forehead, hypertelorism, polydactyly of the fingers and toes, severe motor and mental retardation, hypotonia, and absence of the corpus callosum. The mode of inheritance is discussed and our case is compared with previously reported cases of the syndrome.

Hypogenitalism in the acrocallosal syndrome

We have studied a boy with acrocallosal syndrome and hypogenitalism. He was the offspring of double first cousins. He had unusual facial appearance, postaxial polydactyly with unilateral soft tissue syndactyly of fingers, mental retardation, and absence of corpus callosum. Findings in the present case were compared with those of previously reported cases. Other syndromes associated with agenesis of the corpus callosum must be differentiated. The main differences between the acrocallosal syndrome and the Greig syndrome are outlined with particular emphasis on digital anomalies. The acrocallosal syndrome is an autosomal recessive trait with variable expressivity. Hypogenitalism may be a presenting feature. Positive consanguinity provides further evidence for autosomal recessive inheritance.

Acrocallosal syndrome: additional manifestations

The acrocallosal syndrome (ACS) is a probable autosomal recessive condition of macrocephaly, craniofacial and hand and foot abnormalities, absence of the corpus callosum, and mental retardation. This patient had characteristics of the ACS but also had a severe congenital heart defect and other visceral malformations. After comparing the ACS with and contrasting it to other disorders, we concluded that the internal organ abnormalities found in this patient probably represent further manifestations of the ACS.

Acrocallosal syndrome in a girl born to consanguineous parents

The present report describes on a 1-year-old girl with macrocephaly, bulging forehead, ocular hypertelorism, antimongoloid palpebral slant, convergent strabismus, atrophy of optic papillae, short philtrum, protruding lips, high-arched palate, bifid uvula, broad trunk, apparently widely spaced nipples, diastasis recti, small umbilical hernia, tapering fingers, fifth-finger clinodactyly, postaxial polydactyly of the left hand, and bilateral hallux duplication. Partial agenesis of the corpus callosum and central diffuse cortical cerebral atrophy was documented on computed tomography. Chromosomes were normal. Parents were related as half first cousins. Their previous pregnancy had ended in a miscarriage. We suggest that this patient has an acrocallosal syndrome inherited as an autosomal recessive trait. This supports other recent reports that have considered this entity to differ from Greig cephalopolysyndactyly.

Acrocallosal syndrome: new findings

We describe a 21-month-old girl with typical manifestations of the acrocallosal syndrome of craniofacial anomalies, agenesis of the corpus callosum, hallucal duplication, severe hypotonia, and psychomotor retardation. Our patient also had the Dandy-Walker malformation, imperforate anus with rectovaginal fistula, hypothalamic dysfunction with hypothyroidism and diabetes insipidus, thick, dysplastic pulmonic valve leaflets, central and obstructive apnea, and pulmonary hypertension. These findings add to the delineation of this syndrome.

The acrocallosal syndrome in first cousins: widening of the spectrum of clinical features and further support for autosomal recessive inheritance

First cousins, related through their mothers, showed a pattern of craniofacial, brain, and limb anomalies consistent with the acrocallosal syndrome. Both patients had a defect of the corpus callosum, macrocephaly with a protruding forehead and occiput, hypertelorism, non-horizontal palpebral fissures, a small nose, notched ear lobes, and postaxial polydactyly of the hands. The boy, in addition, had hypospadias, cryptorchidism, inguinal hernias, duplication with syndactyly of the phalanges of the big toe, and a bipartite right clavicle. The girl had an arachnoidal cyst, a calvarian defect, and digitalisation of the thumbs. Motor and mental development was retarded in both patients. This observation provides further evidence of probable autosomal recessive inheritance of the acrocallosal syndrome and widens the spectrum of clinical findings and the variability of features in this rare malformation syndrome.

Callosal defect, microcephaly, severe mental retardation, and other anomalies in three sibs

This study concerns an apparently lethal and previously undescribed syndrome of hypoplastic corpus callosum, microcephaly, severe mental retardation, preauricular skin tag, camptodactyly, growth retardation, and recurrent bronchopneumonia. This combination of anomalies is probably inherited as an autosomal recessive trait. A brief literature review of the anomalies or syndromes associated with callosal defects is discussed.

The acrocallosal syndrome

The acrocallosal syndrome is characterized by peculiar facies, polydactyly of the hands and/or feet, and agenesis of the corpus callosum. Two unrelated 4-month-old boys with consanguineous parents are reported. Both exhibited the main features of the syndrome, but neither of them had partial reduplication of halluces. Consequently, pre-axial polydactyly of the feet is not considered to be a constant feature of the acrocallosal syndrome. The similarity of the acrocallosal syndrome to Greig syndrome is discussed, but it appears unlikely that the two syndromes are identical. Consanguinity in both cases is a strong argument in favour of a recessive mode of inheritance.

Heterogeneity and variability in the oral-facial-digital syndromes

The oral-facial-digital syndromes are a heterogeneous group of conditions sharing oral, facial, and digital anomalies. Based on more or less subtle clinical differences, at least seven causally different entities can be identified in this group. These include 1) oral-facial-digital syndrome (OFDS) I; 2) Mohr syndrome (OFDS II); 3) OFDS III; 4) OFDS with tibial anomalies (OFDS IV); 5) Thurston syndrome; 6) Varadi syndrome; and 7) Whelan syndrome. However, since differentiation between these entities is based on clinical findings, this classification should be viewed as tentative until more definitive methods are available.

Craniofrontonasal dysplasia

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Clinicopathological findings associated with agenesis of the corpus callosum

Seven hundred five cases of agenesis of the corpus callosum (ACC) are reviewed from the literature (n = 660) and from our own observations (n = 45). The diagnosis was made or confirmed using neuroradiological techniques (n = 519) and necropsy or surgery (n = 231). Association with abnormalities often of chromosomes 8, 11, 13-15 and 18 suggests their involvement in abnormal corpus callosum (CC) morphogenesis. Four syndromes (e.g. Aicardi, acrocallosal, Andermann and Shapiro) are characterized by ACC, while others are only sporadically associated (e.g. fetal alcohol syndrome, Dandy-Walker syndrome, Leigh disease, Arnold-Chiari II syndrome). In non-Aicardi patients, the male-to-female ratio was 3:2 and X-linked recessive inheritance is postulated to play a role in some cases. Common abnormalities in acallosal patients included: mental retardation (MR), 73% [corrected]; seizures, 42%; ocular anomalies, 42%; gyral abnormalities, 32%; hydrocephalus, 23%; other central nervous system (CNS) lesions, 29%; costovertebral defects, 24%. Developmental disabilities are not attributable to absence of the CC per se, but due to other CNS malformation or dysfunction, which may be genetic or non-genetic. Future research using recombinant DNA techniques will enable isolation and identification of specific chromosomal defects in those cases with a genetic abnormality.

The acrocallosal syndrome in sisters

Two sisters born to non-consanguineous healthy parents are described who present the following abnormalities: macrocephalus, prominent forehead, hypertelorism, absence of the corpus callosum, inguinal hernias, duplication of hallucal phalanges and severe mental retardation. The older sister in addition had cleft palate, while only the younger had a supratentorial cyst between cerebrum and cerebellum and epileptic fits. After 6 sporadic cases, this is the first instance of siblings with the acrocallosal syndrome. This observation and definite and possible parental consanguinity in two further patients suggest that this syndrome might be recessively inherited.

Megalencephaly: types, clinical syndromes, and management

The differential diagnosis of megalencephaly poses a challenge to the clinician. The two major categories, metabolic and anatomic, include a number of conditions, many of them rare. This article provides a systematic approach to the patient with megalencephaly.

Duplication of hands and feet, multiple joint dislocations, absence of corpus callosum and hypsarrhythmia: acrocallosal syndrome?

We describe a 14-month-old female infant with absence of corpus callosum, atrophy of optic nerve, peculiar face, complex polydactyly, multiple joint abnormalities, and femoral shortness. The similarities to and differences from previously reported cases of this kind suggest that our patient has a new type of acrocallosal syndrome.

Duplication of the hallux

Sixteen patients with duplication of the hallux were reviewed. Follow-up averaged 21 years. Duplication may be classified into three groups: simple hallucal duplication, a transitional type with a short thick first metatarsal, and complete first ray duplication. Routine removal of the most medial hallux or ray is to be avoided. Careful preoperative assessment is necessary to compare hallucal function, cosmesis, and metatarsal weightbearing. Surgery should also correct the associated congenital hallux varus. Surgical complications include functionless hallucis from inappropriate selection and medial soft tissue contractures with either recurrence of the hallux varus or the gradual development of a hallux varus interphalangeus.

A computerised data base for the diagnosis of rare dysmorphic syndromes

A system is described for the computerised storage and retrieval of information on rare dysmorphic syndromes. The clinician can ask a microcomputer for a list of syndromes with any logical combination of physical abnormalities. A descriptive title and full references are also provided on request. Similar systems would be applicable to other medical specialties.

Agenesis of the corpus callosum in ddN strain mouse associated with unusual facial appearance (flat-face)

In the course of an experiment involving brother-sister matings between ddN strain mice, mice occurred with an unusual facial appearance (flat-face). Subsequently, 4 mice with flat-face were bred from the litters of the second birth (ca. 10% frequency). This flat-face was assumed to be the result of a malformed short nose, hypoplastic maxilla and mandible, and hypertelorism. These 4 flat-face mice exhibited no significant delays in growth, motor ability or the development of learning ability. Histologically, they were all characterized by an almost total absence of callosal fibers and the presence of abnormal longitudinal neuromatous bundles. Therefore, the flat-face mice may be useful as experimental animals for brain research, as one can easily judge that they lack the corpus callosum from the facial appearance.