Seckel-like syndrome in three siblings

DNA Replication proteins in primary microcephaly syndromes

SCOPE

Improper expansion of neural stem and progenitor cells during brain development manifests in primary microcephaly. It is characterized by a reduced head circumference, which correlates with a reduction in brain size. This often corresponds to a general underdevelopment of the brain and entails cognitive, behavioral and motoric retardation. In the past decade significant research efforts have been undertaken to identify genes and the molecular mechanisms underlying microcephaly. One such gene set encompasses factors required for DNA replication. Intriguingly, a growing body of evidence indicates that a substantial number of these genes mediate faithful centrosome and cilium function in addition to their canonical function in genome duplication. Here, we summarize, which DNA replication factors are associated with microcephaly syndromes and to which extent they impact on centrosomes and cilia. This article is protected by copyright. All rights reserved.

Cochlear Implantation in Extraordinary Cases

BACKGROUND

Although cochlear implantation has been almost a standard otological procedure worldwide, it may still create a dilemma for the surgeon in some unusual instances such as Seckel syndrome, aural atresia and posterior fossa arachnoid cyst.

CASE REPORT

Three extraordinary cases of cochlear implantation were reported. The first case was a case of Seckel syndrome with a cardiac pacemaker due to complete atrioventricular block. The second case had posterior fossa arachnoid cyst that had retrosigmoid cyst removal and cochlear implantation simultaneously. The last case had cochlear implantation in the ear with congenital aural atresia. All cases could be implanted successfully with full electrode insertion and good audiological outcome. Delayed facial paralysis that occurred in the patient with arachnoid cyst resolved spontaneously.

CONCLUSION

This study addressed the efficiency of cochlear implantation in cases of Seckel syndrome, complete atrioventricular block managed with cardiac pacemaker, congenital aural atresia and posterior fossa arachnoid cyst. In addition, the retrosigmoid approach and cochlear implantation can be performed simultaneously.

Disruption of mouse Cenpj, a regulator of centriole biogenesis, phenocopies Seckel syndrome

Disruption of the centromere protein J gene, CENPJ (CPAP, MCPH6, SCKL4), which is a highly conserved and ubiquitiously expressed centrosomal protein, has been associated with primary microcephaly and the microcephalic primordial dwarfism disorder Seckel syndrome. The mechanism by which disruption of CENPJ causes the proportionate, primordial growth failure that is characteristic of Seckel syndrome is unknown. By generating a hypomorphic allele of Cenpj, we have developed a mouse (Cenpj(tm/tm)) that recapitulates many of the clinical features of Seckel syndrome, including intrauterine dwarfism, microcephaly with memory impairment, ossification defects, and ocular and skeletal abnormalities, thus providing clear confirmation that specific mutations of CENPJ can cause Seckel syndrome. Immunohistochemistry revealed increased levels of DNA damage and apoptosis throughout Cenpj(tm/tm) embryos and adult mice showed an elevated frequency of micronucleus induction, suggesting that Cenpj-deficiency results in genomic instability. Notably, however, genomic instability was not the result of defective ATR-dependent DNA damage signaling, as is the case for the majority of genes associated with Seckel syndrome. Instead, Cenpj(tm/tm) embryonic fibroblasts exhibited irregular centriole and centrosome numbers and mono- and multipolar spindles, and many were near-tetraploid with numerical and structural chromosomal abnormalities when compared to passage-matched wild-type cells. Increased cell death due to mitotic failure during embryonic development is likely to contribute to the proportionate dwarfism that is associated with CENPJ-Seckel syndrome.

Open and closed lip schizencephaly in Seckel syndrome: a case report

Seckel syndrome (Online Mendelian Inheritance in Man database Number 210600) is the classic prototype of primordial bird-headed dwarfism. In addition to the characteristic craniofacial dysmorphism and skeletal defects, abnormalities of the cardiovascular, hematopoietic, endocrine, and central nervous systems are described. The full phenotypic spectrum of this clinically and genetically heterogeneous syndrome is yet to be delineated. Presented herein is a boy 2 years and 5 months old, with Seckel syndrome, born to second-degree consanguineous Muslim parents. In addition to the classic phenotype of the disorder, this patient had both, an open and a closed lip schizencephaly detected on cranial computed tomography (CT) scan. To our knowledge, the association of schizencephaly and Seckel syndrome is not described previously in the English language literature. In addition, presented briefly is a review of the anatomical cerebral cortical malformations associated with this syndrome.

Intrauterine programming of ageing

Ageing is an unavoidable corollary to being alive; the most intuitive interpretation of ageing being that it is the consequence of progressive body degeneration. In agreement with this, current models propose that ageing occurs through a stepwise accumulation of DNA damage, which ultimately limits the regenerative capacity of tissues. On the other hand, there is increasing evidence that fetal distress can influence the development of disease in adult life, a phenomenon known as 'intrauterine programming'. The extent to which an intrauterine exposure to DNA damage can compromise lifespan remains unclear. My group has recently generated a murine model of a human syndrome linked to defective DNA repair and observed that these animals age prematurely, but the accumulation of DNA damage is restricted mostly to the embryonic period. Here, I discuss the implications of this finding and propose that ageing can be influenced by fetal distress.

A mouse model of ATR-Seckel shows embryonic replicative stress and accelerated aging

Although DNA damage is considered a driving force for aging, the nature of the damage that arises endogenously remains unclear. Replicative stress, a source of endogenous DNA damage, is prevented primarily by the ATR kinase. We have developed a mouse model of Seckel syndrome characterized by a severe deficiency in ATR. Seckel mice show high levels of replicative stress during embryogenesis, when proliferation is widespread, but this is reduced to marginal amounts in postnatal life. In spite of this decrease, adult Seckel mice show accelerated aging, which is further aggravated in the absence of p53. Together, these results support a model whereby replicative stress, particularly in utero, contributes to the onset of aging in postnatal life, and this is balanced by the replicative stress-limiting role of the checkpoint proteins ATR and p53.

An anesthetic experience in a patient with Seckel syndrome: A case report

Seckel syndrome is an autosomal recessive, primordial dwarfism. The clinical symptoms and signs include severe intrauterine and postnatal growth retardation, nanocephaly, proportional dwarfism, bird-like faces, beak-like triangular nose, and mental retardation. We report a successful anesthetic management including endotracheal intubation with the GlideScope(R) video laryngoscope in an 18-year old man with Seckel syndrome for curettage of chronic osteomyelitis of pelvic bone.

Deletion of the developmentally essential gene ATR in adult mice leads to age-related phenotypes and stem cell loss

Developmental abnormalities, cancer, and premature aging each have been linked to defects in the DNA damage response (DDR). Mutations in the ATR checkpoint regulator cause developmental defects in mice (pregastrulation lethality) and humans (Seckel syndrome). Here we show that eliminating ATR in adult mice leads to defects in tissue homeostasis and the rapid appearance of age-related phenotypes, such as hair graying, alopecia, kyphosis, osteoporosis, thymic involution, fibrosis, and other abnormalities. Histological and genetic analyses indicate that ATR deletion causes acute cellular loss in tissues in which continuous cell proliferation is required for maintenance. Importantly, thymic involution, alopecia, and hair graying in ATR knockout mice were associated with dramatic reductions in tissue-specific stem and progenitor cells and exhaustion of tissue renewal and homeostatic capacity. In aggregate, these studies suggest that reduced regenerative capacity in adults via deletion of a developmentally essential DDR gene is sufficient to cause the premature appearance of age-related phenotypes.

Anesthesia for cleft lip surgery in a child with Seckel syndrome--a case report

We describe the anesthetic management of a 5-year-old girl diagnosed with Seckel syndrome, for cleft lip surgery. The syndrome is characterized by severe intrauterine and postnatal growth retardation with proportional dwarfism, typical beak-like triangular nose, and mental retardation, accounting for its various synonyms such as bird-headed dwarfism, microcephalic primordial dwarfism, nanocephalic dwarfism and Seckel-type dwarfism.

[Rare forms of female pseudohermaphroditism: when to investigate?]

The congenital adrenal hyperplasia is the commonest cause of ambiguity of the external genitalia at birth, due to classic forms of 21-hydroxylase and 11beta-hydroxylase deficiencies. 3beta-hydroxysteroid dehydrogenase (3betaHSD) is a rare disorder that affects both sexes and female patients may have ambiguous genitalia. Familial glucocorticoid resistance is characterized by increased cortisol secretion without clinical evidence of hypercortisolism, but with manifestations of androgen and mineralocorticoid excess, caused by glucocorticoid receptor gene mutation, and rarely can lead to female pseudohermaphroditism. Placental aromatase deficiency is a rare disease characterized by a masculinized female fetus and a virilized mother, which should be considered in the absence of fetal adrenal hyperplasia and maternal androgen-secreting tumours. Finally, mutations of P450 oxidoreductase causes disordered steroidogenesis with ambiguous genitalia. The investigation of abnormal sexual development requires an initial karyotype analysis and serum 17OH progesterone, 11 deoxycortisol, 17 pregnenolone, and androgen measurements to assess the diagnosis of different forms of congenital adrenal hyperplasia.

Is the novel SCKL3 at 14q23 the predominant Seckel locus?

Seckel syndrome (SCKL) is a rare disease with wide phenotypic heterogeneity. A locus (SCKL1) has been identified at 3q and another (SCKL2) at 18p, both in single kindreds afflicted with the syndrome. We report here a novel locus (SCKL3) at 14q by linkage analysis in 13 Turkish families. In total, 18 affected and 10 unaffected sibs were included in the study. Of the 10 informative families, nine with parental consanguinity and one reportedly nonconsanguineous but with two affected sibs, five were indicative of linkage to the novel locus. One of those families also linked to the SCKL1 locus. A consanguineous family with one affected sib was indicative of linkage to SCKL2. The novel gene locus SCKL3 is 1.18 cM and harbors ménage a trois 1, a gene with a role in DNA repair.