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

Seckel Dwarfism-A Rare Autosomal Recessive Inherited Syndrome: A Case Report

Seckel syndrome, also commonly called Seckel dwarfism, is a rare congenital disorder and always associated with severe growth retardation in utero. This retarded growth lingers on and causes serious developmental deformities ensuing to short stature, microcephaly, mental retardation, and a beak-like nose. This case report intends to present an interesting case of a 14-year-old female patient with various clinical manifestations, typical radiographic features, and characteristic dental manifestations correlated with the literature. A detailed understanding of the present case would assist pediatric dentists in correct and prompt diagnosis, precise treatment, and the prevention of severe consequences caused by Seckel syndrome.

How to cite this article

Tatiya N, Kesri R, Ukey A. Seckel Dwarfism-A Rare Autosomal Recessive Inherited Syndrome: A Case Report. Int J Clin Pediatr Dent 2024;17(2):211-215.

Repercussões fonoaudiológicas na Síndrome de Seckel: estudo de caso

Resumo: Síndrome de Seckel, trata-se de condição rara e de herança autossômica recessiva, hereditário, caracterizada por um severo retardo de crescimento intra-uterino, baixa estatura proporcional, microcefalia com queixo retraído e pequeno, nariz grande e curvo, em alguns casos retardo mental, várias anomalias congênitas em face, crânio e esqueleto, entre outras malformações. O objetivo deste estudo foi identificar as manifestações fonoaudiológicas encontradas nesta Síndrome, a partir do relato de um caso clínico, de um paciente do gênero masculino, de 09 anos de idade, encaminhado pela odontopediatria, com queixa de alteração no padrão respiratório. Foi realizada avaliação fonoaudiológica que abordou: descrição física, aspectos das funções estomatognáticas, da linguagem oral e escrita, da voz e audição e dos aspectos cognitivos. Para complementação do diagnóstico fonoaudiológico, foram realizadas avaliações ortodôntica, otorrinolaringológica e fisioterapêutica. Com relação às funções estomatognáticas, a criança apresentou respiração de modo oral, mastigação com preensão dos alimentos nos dentes laterais, mastigação unilateral, com lábios entreabertos e movimentos exagerados da musculatura perioral; deglutição com interposição de língua e participação da musculatura orofacial. Fala com articulação imprecisa e travada, devido à limitação de abertura de boca. No tocante à voz, o paciente apresentou tempo máximo de fonação reduzido, laringe em posição elevada, ressonância nasal, ataques vocais suaves e intensidade fraca. Não fora observada nenhuma alteração na linguagem oral e escrita. A escassez de estudos relatando manifestações fonoaudiológicas na Síndrome de Seckel, associada à raridade de ocorrência, justifica o interesse em realizar este estudo, para colaboração de maior conhecimento por parte dos fonoaudiólogos e profissionais de saúde.

Primordial dwarfism: overview of clinical and genetic aspects

Primordial dwarfism is a group of genetic disorders which include Seckel Syndrome, Silver-Russell Syndrome, Microcephalic Osteodysplastic Primordial Dwarfism types I/III, II and Meier-Gorlin Syndrome. This genetic disorder group is characterized by intra-uterine growth retardation and post-natal growth abnormalities which occur as a result of disorganized molecular and genomic changes in embryonic stage and, thus, it represents a unique area to study growth and developmental abnormalities. Lot of research has been carried out on different aspects; however, a consolidated review that discusses an overall spectrum of this disorder is not accessible. Recent research in this area points toward important molecular and cellular mechanisms in human body that regulate the complexity of growth process. Studies have emerged that have clearly associated with a number of abnormal chromosomal, genetic and epigenetic alterations that can predispose an embryo to develop PD-associated developmental defects. Finding and associating such fundamental changes to its subtypes will help in re-examination of alleged functions at both cellular and developmental levels and thus reveal the intrinsic mechanism that leads to a balanced growth. Although such findings have unraveled a subtle understanding of growth process, we further require active research in terms of identification of reliable biomarkers for different subtypes as an immediate requirement for clinical utilization. It is hoped that further study will advance the understanding of basic mechanisms regulating growth relevant to human health. Therefore, this review has been written with an aim to present an overview of chromosomal, molecular and epigenetic modifications reported to be associated with different subtypes of this heterogenous disorder. Further, latest findings with respect to clinical and molecular genetics research have been summarized to aid the medical fraternity in their clinical utility, for diagnosing disorders where there are overlapping physical attributes and simultaneously inform about the latest developments in PD biology.

A complex microcephaly syndrome in a Pakistani family associated with a novel missense mutation in RBBP8 and a heterozygous deletion in NRXN1

We report on a consanguineous Pakistani family with a severe congenital microcephaly syndrome resembling the Seckel syndrome and Jawad syndrome. The affected individuals in this family were born to consanguineous parents of whom the mother presented with mild intellectual disability (ID), epilepsy and diabetes mellitus. The two living affected brothers presented with microcephaly, white matter disease of the brain, hyponychia, dysmorphic facial features with synophrys, epilepsy, diabetes mellitus and ID. Genotyping with a 250K SNP array in both affected brothers revealed an 18 MB homozygous region on chromosome 18 p11.21-q12.1 encompassing the SCKL2 locus of the Seckel and Jawad syndromes. Sequencing of the RBBP8 gene, underlying the Seckel and Jawad syndromes, identified the novel mutation c.919A>G, p.Arg307Gly, segregating in a recessive manner in the family. In addition, in the two affected brothers and their mother we have also found a heterozygous 607kb deletion, encompassing exons 13-19 of NRXN1. Bidirectional sequencing of the coding exons of NRXN1 did not reveal any other mutation on the other allele. It thus appears that the phenotype of the mildly affected mother can be explained by the NRXN1 deletion, whereas the more severe and complex microcephalic phenotype of the two affected brothers is due to the simultaneous deletion in NRXN1 and the homozygous missense mutation affecting RBBP8.

The shortest of the short: pericentrin mutations and beyond

Microcephalic or Majewski's osteodysplastic primordial dwarfism type II (MOPD II) represents the most common type of primordial dwarfism. Adult height is typically about one meter and short stature is becoming mildly disproportionate over time with mild skeletal anomalies. Mental development is usually borderline or within the low normal range but cerebrovascular events that are common in childhood can result in significant cognitive impairment and cerebral palsy. Despite cerebrovascular insults, cardiomyopathy and early onset type 2 diabetes contribute to early mortality and morbidity. Common minor clinical features are truncal obesity, high pitched voice, microdontia and pigmentary changes. MOPD II is caused by autosomal recessive loss of function mutations in the PCNT gene encoding for a key centrosomal protein. There is clinical overlap with the so called Seckel syndrome, a heterogeneous group of entities with at least four different gene loci known to date.

Growth hormone treatment, final height, insulin-like growth factors, ghrelin, and adiponectin in four siblings with Seckel syndrome

OBJECTIVE

To report on the effect of growth hormone (GH) treatment on final height (FH) and to describe the insulin-like growth factor (IGF) system, ghrelin, and adiponectin (ADPN) in children with Seckel syndrome.

SUBJECTS AND RESULTS

Four severely growth-retarded Iraqi siblings (two girls and two boys) with Seckel syndrome were referred at ages 16.5, 14.4, 12.4, and 10.4 years. They were born at term, but their growth was retarded and birth weight ranged between 1 and 1.5 kg. The children were healthy and had a normal response to GH provocative test. Long-term GH treatment of the youngest brother and sister increased the FH by 7.2 and 3.4 cm, respectively, compared with their older brother and sister. At FH, body mass index standard deviation scores (BMISDS) ranged from -3.0 to -3.9. Serum levels of immunoreactive IGF-1, bioactive IGF-1, and IGF-binding protein 3 were all within normal to high range before GH treatment and increased after GH treatment. Fasting plasma ghrelin remained severely reduced. Despite low BMISDS, plasma ADPN was moderately reduced and showed an almost complete absence of the low-molecular-weight subform.

CONCLUSION

This is the first report on the effect of GH treatment on FH in children with Seckel syndrome. GH may have increased FH. In addition to growth defects and reduced BMISDS, patients with Seckel syndrome are characterized by low fasting ghrelin levels, low total ADPN, and near deficiency of the low-molecular-weight ADPN subform. The possible significance of the hormonal changes requires further investigations.

Seckel syndrome with chromosomal 18 deletion

Four case records of patients with Seckel Syndrome (SS) were retrieved. Typical of bird headed dwarfism was seen in all. Chromosome 18 deletion was seen in one child with SS. MRI abnormalities were detected in 3 patients. Cytogenetic studies and neuroimaging is likely to provide important diagnostic and prognostic information.

Seckel syndrome and moyamoya

Seckel syndrome is an autosomal recessive disorder characterized by intrauterine and postnatal growth delay, microcephaly with mental retardation, and facial dysmorphisms including micrognathia, a recessed forehead, and a large beaked nose. Occurring in 1 in 10,000 children without sex preference, it is the most common primordial microcephalic osteodysplastic dwarfism and has been associated with a variety of congenital brain malformations and intracranial aneurysms. Moyamoya syndrome is an idiopathic, chronic, progressive cerebrovascular disorder marked by stenosis of the intracranial internal carotid arteries and concurrent development of hypertrophied collateral vessels. These tortuous arterial collaterals appear radiographically as "puffs of smoke," giving the syndrome its name. In this report, the authors describe the case of a 16-year-old girl with coincident Seckel and moyamoya syndromes. To their knowledge, this is the first reported case of such an association being treated with surgical revascularization. The patient presented with persistent headaches and a 2-year history of progressive hand, arm, and face numbness. Imaging studies revealed multiple completed cerebral infarcts, global ischemic changes, and vascular anatomy consistent with moyamoya syndrome. Bilateral pial synangioses successfully revascularized each hemisphere with resolution of the patient's symptoms. The patient died 1 year later of complications related to treatment of a rapidly progressing intracranial aneurysm. This report documents the first case associating moyamoya and Seckel syndromes. In addition, the report reveals the rapid development of an intracranial aneurysm in a patient with this syndrome. When coupled with previous reports of other types of cerebrovascular disease in patients with Seckel syndrome or other primordial dwarfisms, the authors' findings are important because they suggest that physicians treating patients with dwarfism should consider the diagnosis of moyamoya syndrome when symptoms suggestive of cerebral ischemia are present. Prompt diagnosis and treatment of moyamoya syndrome, including the use of proven surgical revascularization procedures such as pial synangiosis, may significantly improve the long-term outcomes of these patients.

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.

The role of the DNA damage response pathways in brain development and microcephaly: insight from human disorders

A network of DNA damage response (DDR) mechanisms functions co-ordinately to maintain genomic stability and ensure cellular survival in the face of exogenous and endogenous DNA damage. Defects in DDR pathways have been identified in a range of human disorders, collectively classified as DDR-defective syndromes. A common feature of these syndromes is a predisposition to cancer demonstrating the importance of the DDR in cancer avoidance. How the DDR mechanisms serve to maintain genomic stability has been the predominant focus of research into their function. However, many DRR-defective syndromes are also characterised by impaired development demonstrating broader roles for the DDR mechanisms. Microcephaly, representing reduced brain size, is a feature common to a diverse range of DDR-defective disorders. Microcephaly is most likely caused by loss (increased cell death) or failure of the developing neuronal stem cells or their progenitors to divide suggesting a fundamental role for the DDR in maintaining proliferative potential in the developing nervous system. Currently, it is unclear why the DDR proteins should be more important during neuronal development compared with the development of other tissues or why the embryonic brain is more sensitive than the adult brain. Here, we overview the DDR-defective disorders in the context of microcephaly and discuss a model underlying this striking phenotype.

The genetic basis of inherited anomalies of the teeth. Part 2: syndromes with significant dental involvement

Teeth are specialized structural components of the craniofacial skeleton. Developmental defects occur either alone or in combination with other birth defects. In this paper, we review the dental anomalies in several multiple congenital anomaly (MCA) syndromes, in which the dental component is pivotal in the recognition of the phenotype and/or the molecular basis of the disorder is known. We will consider successively syndromic forms of amelogenesis imperfecta or enamel defects, dentinogenesis imperfecta (i.e. osteogenesis imperfecta) and other dentine anomalies. Focusing on dental aspects, we will review a selection of MCA syndromes associated with teeth number and/or shape anomalies. A better knowledge of the dental phenotype may contribute to an earlier diagnosis of some MCA syndromes involving teeth anomalies. They may serve as a diagnostic indicator or help confirm a syndrome diagnosis.

Haploinsufficiency of DNA Damage Response Genes and their Potential Influence in Human Genomic Disorders

Genomic disorders are a clinically diverse group of conditions caused by gain, loss or re-orientation of a genomic region containing dosage-sensitive genes. One class of genomic disorder is caused by hemizygous deletions resulting in haploinsufficiency of a single or, more usually, several genes. For example, the heterozygous contiguous gene deletion on chromosome 22q11.2 causing DiGeorge syndrome involves at least 20-30 genes. Determining how the copy number variation (CNV) affects human variation and contributes to the aetiology and progression of various genomic disorders represents important questions for the future. Here, I will discuss the functional significance of one form of CNV, haploinsufficiency (i.e. loss of a gene copy), of DNA damage response components and its association with certain genomic disorders. There is increasing evidence that haploinsufficiency for certain genes encoding key players in the cells response to DNA damage, particularly those of the Ataxia Telangiectasia and Rad3-related (ATR)-pathway, has a functional impact. I will review this evidence and present examples of some well known clinically similar genomic disorders that have recently been shown to be defective in the ATR-dependent DNA damage response. Finally, I will discuss the potential implications of a haploinsufficiency-induced defective DNA damage response for the clinical management of certain human genomic disorders.

A syndromic form of autosomal recessive congenital microcephaly (Jawad syndrome) maps to chromosome 18p11.22-q11.2

We report a consanguineous Pakistani family with seven affected individuals showing a syndromic form of congenital microcephaly. Clinical features of affected individuals include congenital microcephaly with sharply slopping forehead, moderate to severe mental retardation, anonychia congenita, and digital malformations. By screening human genome with microsatellite markers, this autosomal recessive condition was mapped to a 25.2 cM interval between markers D18S1150 and D18S1100 on chromosome 18p11.22-q12.3. However, the region of continuous homozygosity between markers D18S1150 and D18S997 spanning 15.33 cM, probably define the most likely candidate region for this condition. This region encompasses a physical distance of 12.03 Mb. The highest two-point LOD score of 3.03 was obtained with a marker D18S1104 and multipoint score reached a maximum of 3.43 with several markers. Six candidate genes, CEP76, ESCO1, SEH1L, TUBB6, ZNF519, and PTPN2 were sequenced, and were found to be negative for functional sequence variants.

Pentoxifylline suppresses transduction by HIV-1-based vectors

Pentoxifylline, a caffeine-related compound, was shown to suppress human immunodeficiency virus type 1 (HIV-1) replication. This effect is thought to be mediated by inhibition of tumor necrosis factor-alpha (TNFalpha)-mediated long-terminal repeat (LTR)-driven expression. We now demonstrate that pentoxifylline efficiently inhibits transduction by HIV-1-based vectors. This latter effect is independent of LTR-driven expression, and correlates with a reduced efficiency of the completion of the integration process in infected cells. Finally, the effect of pentoxifylline is dramatically reduced in cells expressing a dominant negative ATR protein, and in primary human cells that exhibit low level of ATR activity, suggesting that the effect of pentoxifylline on HIV-1 transduction and replication is at least partly mediated by suppression of the ATR kinase.

Pigmentary changes and atopic dermatitis in a patient with Seckel syndrome

Seckel syndrome is a very rare form of primordial dwarfism characterized by antenatal and postnatal growth delay, proportionate extreme short stature, a prominent beak-like nose, hypoplasia of the malar area, small chin, microcephaly, deformed ears lacking lobules, skeletal malformations, mental retardation, and developmental delay. This syndrome has been described with associated disorders of orthopedic, neurologic, hematologic, cardiac, and ocular systems; however, only a few reports mention dermatologic involvement. We describe a 5-year-old girl with classic Seckel syndrome who presented with moderately severe atopic dermatitis and diffuse hypopigmented macules and papules.

Uveal coloboma: clinical and basic science update

PURPOSE OF REVIEW

To integrate knowledge on the embryologic and molecular basis of optic fissure closure with clinical observations in patients with uveal coloboma.

RECENT FINDINGS

Closure of the optic fissure has been well characterized and many genetic alterations have been associated with coloboma; however, molecular mechanisms leading to coloboma remain largely unknown. In the past decade, we have gained better understanding of genes critical to eye development; however, mutations in these genes have been found in few individuals with coloboma. CHD7 mutations have been identified in patients with CHARGE syndrome (coloboma, heart defects, choanal atresia, retarded growth, genital anomalies, and ear anomalies or deafness). Animal models are bringing us closer to a molecular understanding of optic fissure closure.

SUMMARY

Optic fissure closure requires precise orchestration in timing and apposition of two poles of the optic cup. The relative roles of genetics and environment on this process remain elusive. While most cases of coloboma are sporadic, autosomal dominant, autosomal recessive, and X-linked inheritance patterns have been described. Genetically, colobomata demonstrate pleiotropy, heterogeneity, variable expressivity, and reduced penetrance. Coloboma is a complex disorder with a variable prognosis and requires regular examination to optimize visual acuity and to monitor for potential complications.

3-M syndrome: a report of three Egyptian cases with review of the literature

The 3-M syndrome is a rare autosomal recessive disorder. It is characterized by prenatal and postnatal growth retardation associated with characteristic features. In this study, we report on three patients from two unrelated families, including two male sibs, with the characteristic features and radiological findings of the 3-M syndrome. The main features in our cases were low birth weight, short stature, malar hypoplasia, anteverted nostrils with a fleshy nasal tip, long philtrum, pointed full chin, short broad neck, broad chest with transverse grooves of anterior thorax and hyperlordosis. An orodental examination revealed characteristic findings, some of which were not reported before. Prominent premaxilla, hypoplastic maxilla, thick patulous lips, high-arched palate, median fissured tongue, delayed eruption of teeth with enamel hypocalcification and malocclusion were present in our three studied cases. Radiographic studies showed slender long bones and ribs, a narrow pelvis and foreshortened vertebral bodies. Our reported cases are the offspring of healthy consanguineous parents, confirming the autosomal recessive pattern of inheritance in the syndrome. Cases were reported from different countries all over the world. To our knowledge, these are the first reported Egyptian patients with this rare disorder. This syndrome may be underreported because of the phenotypic overlap with other low birth dwarfism syndromes. Recent identification of a gene mutated in some cases of 3-M syndrome will aid diagnosis.

Disparate roles of ATR and ATM in immunoglobulin class switch recombination and somatic hypermutation

Class switch recombination (CSR) and somatic hypermutation (SHM) are mechanistically related processes initiated by activation-induced cytidine deaminase. Here, we have studied the role of ataxia telangiectasia and Rad3-related protein (ATR) in CSR by analyzing the recombinational junctions, resulting from in vivo switching, in cells from patients with mutations in the ATR gene. The proportion of cells that have switched to immunoglobulin (Ig)A and IgG in the peripheral blood seems to be normal in ATR-deficient (ATRD) patients and the recombined S regions show a normal "blunt end-joining," but impaired end joining with partially complementary (1-3 bp) DNA ends. There was also an increased usage of microhomology at the mu-alpha switch junctions, but only up to 9 bp, suggesting that the end-joining pathway requiring longer microhomologies (> or =10 bp) may be ATR dependent. The SHM pattern in the Ig variable heavy chain genes is altered, with fewer mutations occurring at A and more mutations at T residues and thus a loss of strand bias in targeting A/T pairs within certain hotspots. These data suggest that the role of ATR is partially overlapping with that of ataxia telangiectasia-mutated protein, but that the former is also endowed with unique functional properties in the repair processes during CSR and SHM.

Seckel syndrome exhibits cellular features demonstrating defects in the ATR-signalling pathway

To date, the only reported genetic defect identified in the developmental disorder, Seckel syndrome, is a mutation in ataxia telangiectasia and Rad3-related protein (ATR). Seckel syndrome is clinically and genetically heterogeneous and whether defects in ATR significantly contribute to Seckel syndrome is unclear. Firstly, we characterize ATR-Seckel cells for their response to DNA damage. ATR-Seckel cells display impaired phosphorylation of ATR-dependent substrates, impaired G2/M checkpoint arrest and elevated micronucleus (MN) formation following exposure to UV and agents that cause replication stalling. We describe a novel phenotype, designated nuclear fragmentation (NF), that occurs following replication arrest. Finally, we report that ATR-Seckel cells have an endogenously increased number of centrosomes in mitotic cells demonstrating a novel role for ATR in regulating centrosome stability. We exploit these phenotypes to examine cell lines derived from additional unrelated Seckel syndrome patients. We show that impaired phosphorylation of ATR-dependent substrates is a common but not invariant feature of Seckel syndrome cell lines. In contrast, all cell lines displayed defective G2/M arrest, increased levels of NF and MN formation following exposure to agents that cause replication stalling. All the Seckel syndrome cell lines examined showed increased endogenous centrosome numbers. Though ATR cDNA can complement the defects in ATR-Seckel cells, it failed to complement any of the additional cell lines. We conclude that Seckel syndrome represents a further damage response disorder that is uniquely associated with defects in the ATR-signalling pathway resulting in failed checkpoint arrest following exposure to replication fork stalling.

Chromosomal instability at common fragile sites in Seckel syndrome

Seckel syndrome (SCKL) is a rare, genetically heterogeneous disorder, with dysmorphic facial appearance, growth retardation, microcephaly, mental retardation, variable chromosomal instability, and hematological disorders. To date, three loci have been linked to this syndrome, and recently, the gene encoding ataxia-telangiectasia and Rad3-related protein (ATR) was identified as the gene mutated at the SCKL1 locus. The ATR mutation affects splicing efficiency, resulting in low levels of ATR in affected individuals. Elsewhere, we reported increased instability at common chromosomal fragile sites in cells lacking the replication checkpoint gene ATR. Here, we tested whether cells from patients carrying the SCKL1 mutation would show increased chromosome breakage following replication stress. We found that, compared with controls, there is greater chromosomal instability, particularly at fragile sites, in SCKL1-affected patient cells after treatment with aphidicolin, an inhibitor of DNA polymerase alpha and other polymerases. The difference in chromosomal instability between control and patient cells increases at higher levels of aphidicolin treatment, suggesting that the low level of ATR present in these patients is not sufficient to respond appropriately to replication stress. This is the first human genetic syndrome associated with increased chromosome instability at fragile sites following replication stress, and these findings may be related to the phenotypic findings in patients with SCKL1.

An overview of three new disorders associated with genetic instability: LIG4 syndrome, RS-SCID and ATR-Seckel syndrome

Around 15-20 hereditary disorders associated with impaired DNA damage response mechanisms have been previously described. The range of clinical features associated with these disorders attests to the significant role that these pathways play during development. Recently, three new such disorders have been reported extending the importance of the damage response pathways to human health. LIG4 syndrome is conferred by hypomorphic mutations in DNA ligase IV, an essential component of DNA non-homologous end-joining (NHEJ), and is associated with pancytopaenia, developmental and growth delay and dysmorphic facial features. Radiosensitive severe combined immunodeficiency (RS-SCID) is caused by mutations in Artemis, a protein that plays a subsidiary role in non-homologous end-joining although it is not an essential component. RS-SCID is characterised by severe combined immunodeficiency but patients have no overt developmental abnormalities. ATR-Seckel syndrome is caused by mutations in ataxia telangiectasia and Rad3 related protein (ATR), a component of a DNA damage signalling pathway. ATR-Seckel syndrome patients have dramatic microcephaly and marked growth and developmental delay. The clinical features of these patients are considered in the light of the function of the defective protein.