Overgrowth syndromes

Simpson-Golabi-Behmel syndrome type 1 with normal birth parameters

A newborn baby born at 34 weeks and 5 days gestation was admitted for prematurity, dysmorphic features and congenital heart defects. Antenatal scan at 21 weeks showed a large-for-gestational-age foetus with a large abdominal circumference and liver, ventricular septal defect, right prominent renal pelvis and echogenic bowel. Antenatal genetic tests for overgrowth syndromes were negative. The mother had early onset pre-eclampsia. After birth, an overgrowth syndrome was still suspected despite the baby having normal birth parameters. Raw data of the trio whole exome sequencing from the amniocentesis sample were manually inspected. Hemizygous exon 7 deletion in the GPC3 gene was found, and a postnatal diagnosis of Simpson-Golabi-Behmel syndrome, a rare overgrowth syndrome, was made. This case report discusses the significance of antenatal findings, an atypical presentation of a rare syndrome and the obstacles of diagnostic genetic testing.

An investigation of the etiology and follow-up findings in 35 children with overgrowth syndromes, including biallelic SUZ12 variant

Overgrowth-intellectual disability (OGID) syndromes are clinically and genetically heterogeneous group of disorders. The aim of this study was to examine the molecular etiology and long-term follow-up findings of Turkish OGID cohort. Thirty-five children with OGID were included in the study. Single gene sequencing, clinical exome analysis, chromosomal microarray analysis and whole exome sequencing were performed. Five pathogenic copy number variants were detected in the patients; three of them located on chromosome 5q35.2 (encompassing NSD1), others on 9q22.3 and 22q13.31. In 19 of 35 patients; we identified pathogenic variants in OGID genes associated with epigenetic regulation, NSD1 (n = 15), HIST1H1E (n = 1), SETD1B (n = 1), and SUZ12 (n = 2). The pathogenic variants in PIK3CA (n = 2), ABCC9 (n = 1), GPC4 (n = 2), FIBP (n = 1), and TMEM94 (n = 1) which had a role in other growth pathways were detected in seven patients. The diagnostic yield was 31/35(88%). Twelve pathogenic variants were novel. The common facial feature of the patients was prominent forehead. The patients with Sotos syndrome were observed to have milder intellectual disability than patients with other OGID syndromes. In conclusion, this study showed, for the first time, that biallelic variants of SUZ12 caused Imagawa-Matsumoto syndrome, monoallelic variants in SETDIB resulted in OGID. Besides expanded the phenotypes of very rare OGID syndromes caused by FIBP and TMEM94.

Sotos syndrome with a novel mutation in the NSD1 gene associated with congenital hypothyroidism

Childhood overgrowth syndromes are relatively rare. A generalized overgrowth syndrome should be suspected when tall stature and macrocephaly are present, after ruling out nutritional excess and endocrinopathies. Sotos syndrome is a well-described overgrowth syndrome due to haploinsufficiency of the NSD1 gene. We present a case of an infant with permanent congenital hypothyroidism, who had tall stature and macrocephaly by 7 months of age. He was noted to have typical facial features, mild gross motor and speech delay, and scoliosis by 13 months of age. Gene sequencing revealed a heterozygous novel c6076_6087del12: p.Asn2026_Thr2029del variant in exon 20 of the NSD1 gene, pathogenic for Sotos syndrome. Congenital hypothyroidism with Sotos syndrome has been infrequently reported and may expand the spectrum of disease characteristics. Early diagnosis of overgrowth syndromes is important for developmental follow up and multidisciplinary care coordination.

Clinical and Molecular Diagnosis of Beckwith-Wiedemann Syndrome with Single- or Multi-Locus Imprinting Disturbance

Beckwith-Wiedemann syndrome (BWS) is a clinically and genetically heterogeneous overgrowth disease. BWS is caused by (epi)genetic defects at the 11p15 chromosomal region, which harbors two clusters of imprinted genes, IGF2/H19 and CDKN1C/KCNQ1OT1, regulated by differential methylation of imprinting control regions, H19/IGF2:IG DMR and KCNQ1OT1:TSS DMR, respectively. A subset of BWS patients show multi-locus imprinting disturbances (MLID), with methylation defects extended to other imprinted genes in addition to the disease-specific locus. Specific (epi)genotype-phenotype correlations have been defined in order to help clinicians in the classification of patients and referring them to a timely diagnosis and a tailored follow-up. However, specific phenotypic correlations have not been identified among MLID patients, thus causing a debate on the usefulness of multi-locus testing in clinical diagnosis. Finally, the high incidence of BWS monozygotic twins with discordant phenotypes, the high frequency of BWS among babies conceived by assisted reproductive technologies, and the female prevalence among BWS-MLID cases provide new insights into the timing of imprint establishment during embryo development. In this review, we provide an overview on the clinical and molecular diagnosis of single- and multi-locus BWS in pre- and post-natal settings, and a comprehensive analysis of the literature in order to define possible (epi)genotype-phenotype correlations in MLID patients.

Diagnostic Approach to Macrocephaly in Children

Macrocephaly affects up to 5% of the pediatric population and is defined as an abnormally large head with an occipitofrontal circumference (OFC) >2 standard deviations (SD) above the mean for a given age and sex. Taking into account that about 2-3% of the healthy population has an OFC between 2 and 3 SD, macrocephaly is considered as "clinically relevant" when OFC is above 3 SD. This implies the urgent need for a diagnostic workflow to use in the clinical setting to dissect the several causes of increased OFC, from the benign form of familial macrocephaly and the Benign enlargement of subarachnoid spaces (BESS) to many pathological conditions, including genetic disorders. Moreover, macrocephaly should be differentiated by megalencephaly (MEG), which refers exclusively to brain overgrowth, exceeding twice the SD (3SD-"clinically relevant" megalencephaly). While macrocephaly can be isolated and benign or may be the first indication of an underlying congenital, genetic, or acquired disorder, megalencephaly is most likely due to a genetic cause. Apart from the head size evaluation, a detailed family and personal history, neuroimaging, and a careful clinical evaluation are crucial to reach the correct diagnosis. In this review, we seek to underline the clinical aspects of macrocephaly and megalencephaly, emphasizing the main differential diagnosis with a major focus on common genetic disorders. We thus provide a clinico-radiological algorithm to guide pediatricians in the assessment of children with macrocephaly.

Carpal tunnel syndrome in paediatric patients: A novel association with Kosaki overgrowth syndrome

Carpal tunnel syndrome in a paediatric population is vanishingly rare and usually associated with lysosomal storage disorders such as mucopolysaccharidosis (MPS). Overgrowth syndromes similarly are rare and are characterised by increased skeletal growth alongside typical dysmorphic features and intellectual delay and as such the acronym OGID (overgrowth intellectual delay) is now widely used. Kosaki overgrowth syndrome (KOGS) is a newly recognised OGID with only 6 cases to date reported in the literature. Here we report a 7th case of KOGS with a new finding of carpal tunnel syndrome not previously described. We discuss similarities between the intraoperative findings during carpal tunnel decompression with findings seen in patients with MPS.

The importance of anthropological methods in the diagnosis of rare diseases

Most of inborn errors of metabolism (IEMs) and rare endocrine-metabolic diseases (REMD) are rare diseases. According to the European Commission on Public Health, a rare disease is defined, based on its prevalence, as one affecting one in 2000 people. Many IEMs affect body stature, cause craniofacial abnormalities, and disturb the developmental process. Therefore, body proportion, dysmorphic characteristics, and morphological parameters must be assessed and closely monitored. This can be achieved only with the help of an anthropologist who has adequate tools. This is why the role of an anthropologist in collaboration with the physician in the diagnostic process is not to be underestimated. Clinical anthropologists contribute to assessing physical development and improve our understanding of the natural history of rare metabolic diseases. This paper presents anthropometric techniques and methods, such as analysis of demographic data, anthropometric parameters at birth, percentile charts, growth patterns, bioimpedance, somatometric profiles, craniofacial profiles, body proportion indices, and mathematical models of growth curves used in certain rare diseases. Contemporary anthropological methods play an important role in the diagnostic process of rare genetic diseases.

Expanding the Clinical Spectrum of Sotos Syndrome in a Patient with the New "c.[5867T>A]+[=]"; "p.[Leu1956Gln]+[=]" NSD1 Missense Mutation and Complex Skin Hamartoma

Sotos syndrome is one of the most common overgrowth diseases and it predisposes patients to cancer, generally in childhood. The prevalence of this genetic disorder is 1:10,000⁻1:50,000, and it is characterized by wide allelic heterogeneity, with more than 100 different known mutations in the nuclear receptor-binding SET domain containing protein 1 (NSD1) gene. Most of these alterations are deletions and common micro-deletions with haploinsufficiency. Singular variants are missense mutations. The present study reports a case of a 4-year-old boy with specific clinical features of Sotos syndrome and a particular complex skin hamartoma on the right femoral side, in addition to other minor findings, such as a "café-au-lait" spot on the right hemithorax and syndactyly of the second and third right toes. NSD1 gene analysis identified a de novo missense mutation, "c.[5867T>A]+[=]"; "p.[Leu1956Gln]+[=]", that was not previously described in the literature. This mutation was localized to the functional domain of the gene and was likely the cause of Sotos syndrome in our patient. We also compared aspects of our patient's condition with the clinical features of tuberous sclerosis (TSC), which is an autosomal neurocutaneous syndrome caused by mutations in the TSC1/TSC2 genes. These genes control cell growth and cell survival. This disorder is characterized by hamartomas in multiple organ systems, several coetaneous abnormalities, epilepsy, and increased risk of several types of tumors.

A Clinical Review of Generalized Overgrowth Syndromes in the Era of Massively Parallel Sequencing

The overgrowth syndromes are important to diagnose, not just for accurate genetic counseling, but also for knowledge surrounding cancer surveillance and prognosis. There has been a recent expansion in the number of genes associated with a mendelian overgrowth phenotype, so this review updates previous classifications of overgrowth syndromes. We also describe a clinical and molecular approach to the investigation of individuals presenting with overgrowth. This review aims to assist the clinical diagnosis of generalized overgrowth syndromes by outlining the salient features of well-known overgrowth syndromes alongside the many syndromes that have been discovered and classified more recently. We provide key clinical "handles" to aid clinical diagnosis and a list of genes to aid with panel design when using next generation sequencing, which we believe is frequently needed due to the overlapping phenotypic features seen between overgrowth syndromes.

Surgical trauma induces overgrowth in lower limb gigantism: regulation with use of rapamycin is promising

We describe an unclassified overgrowth syndrome characterised by unregulated growth of dermal fibroblasts in the lower limbs of a 35-year-old woman. A PIK3CA gene mutation resulted in lower limb gigantism. Below the waist, she weighed 117 kg with each leg measuring over 100 cm in circumference. Her total adiposity was 50% accounted for by her legs mainly. Liposuction and surgical debulking were performed to reduce the size of the limbs but had exacerbated the overgrowth in her lower limbs. Systemic sepsis from an infected foot ulcer necessitated treatment by an above-knee amputation. Postoperatively, the stump increased in size by 19 kg. A trial of rapamycin to reverse the growth of the stump has shown promise. We discuss the clinical and genetic features of this previously unclassified disorder and the orthopaedic considerations involved.

Identification of a novel de novo nonsense mutation of the NSD1 gene in monozygotic twins discordant for Sotos syndrome

INTRODUCTION

Sotos syndrome is a congenital overgrowth disorder characterized by facial gestalt, excessively rapid growth, acromegalic features and a non-progressive cerebral disorder with intellectual disability.

METHODOLOGY

The identical male twins showed somewhat different clinical, cognitive and behavioural phenotypes. Abnormal clinical manifestations including seizures, scoliosis, enlarged ventricles, and attention-deficit/hyperactivity disorder (ADHD) were found in the proband (first twin), but not in the sibling (second twin). We used diagnostic exome sequencing (DES) to identify a heterozygous de novo mutation of the NSD1 gene in monozygotic twins with Sotos syndrome.

RESULTS

DES revealed a novel nonsense mutation c.2596G>T (p.Glu866*) of the NSD1 gene in the proband, the first of monozygotic twins. Sanger sequencing analysis of the proband and his family members showed that this nonsense mutation was present in the proband and his sibling, but was absent in their parents, indicating that it occurred with de novo origin.

CONCLUSION

This finding expands the phenotypic spectrum associated with variable expression of the Sotos syndrome caused by NSD1 mutation, and it adds further support for postconceptual mutation, epigenetic change and/or an environmental factor involved in the cause of the Sotos syndrome.

Proteus Syndrome with Arteriovenous Malformation

Proteus syndrome is a rare sporadic disorder that appears with localized macrosomia, congenital lipomatosis, and slow flow vascular malformations, connective tissue nevus, and epidermal nevus. There are usually some manifestations at birth. The vascular abnormalities that have been reported in Proteus syndrome are capillary and slow flow venous malformation. We report a case of a 10-year-old boy with confirmed Proteus syndrome characterized by high flow vascular malformation (arteriovenous [AV] malformation) unlike the usual vascular malformations seen in this syndrome. This case adds a new perspective to the established clinical findings of the Proteus syndrome.

A recessive syndrome of intellectual disability, moderate overgrowth, and renal dysplasia predisposing to Wilms tumor is caused by a mutation in FIBP gene

Clinical classification of overgrowth syndromes represents a challenge since a wide spectrum of disorders result in marked overgrowth. Therefore, there is a continuous effort to identify the genetic basis of these disorders that will eventually facilitate their molecular classification. Here, we have identified the genetic etiology and the pathogenetic mechanism underlying a rare autosomal recessive overgrowth syndrome in three affected siblings. The overgrowth phenotype in the patients was accompanied by developmental delay, learning disabilities, and variable congenital abnormalities. To elucidate the genetic etiology of the disorder, whole-genome genotyping and whole-exome sequencing were used. The disease was mapped to 3p21.1-p14.2 and 11q13.1-q13.4, where an in-frame insertion (c.175_176insTAA) in FIBP gene was revealed. The resulting indel (p.H59LN) was predicted to change the protein conformation with likely deleterious effect on its function as one of the fibroblast growth factor signaling mediators. In vitro cellular proliferation assay and in situ hypridization in vivo were then performed to understand the pathophysiology of the disease. The patients' skin fibroblasts showed an increased proliferation capacity compared to the controls' explaining the observed overgrowth phenotype. In addition, we detected Fibp expression most notably in the brains of mice embryos suggesting a possible effect on cognitive functions early in development. To date, only one patient has been reported with a homozygous nonsense mutation in FIBP exhibiting an overgrowth syndrome with multiple congenital abnormalities. Taken all together, these findings provide convincing evidence implicating FIBP aberrations in the newly recognized overgrowth syndrome and expand the associated phenotypes to include possible Wilms tumor predisposition. © 2016 Wiley Periodicals, Inc.

Can Macrosomia or Large for Gestational Age Be Predictive of Mucopolysaccharidosis Type I, II and VI?

BACKGROUND

The objective of the study was to compare mean values for birth body length and weight between patients with mucopolysaccharidosis (MPS) and the general population.

METHODS

A retrospective analysis of birth anthropometric data was performed for patients (n = 103) with MPS I, II, and VI. Two-tailed t tests were used to compare mean values for body length and weight at birth between patients with MPS and the general population.

RESULTS

Mean values for birth body length and weight for all studied groups were greater than in the general population. For body length the differences were statistically significant. When considered individually, 53% of patients were large for gestational age (LGA) and 30% were macrosomic. The highest percentage of LGA was observed in MPS II males and MPS VI females (55% and 56%, respectively), while the highest percentage of macrosomia was observed in MPS VI males (36%).

CONCLUSION

At the time of birth, MPS patients were larger than those in the general population. High birth weight and/or LGA can be suggestive of MPS disease and should raise suspicion aiding early disease recognition.

Burden of Growth Hormone Deficiency and Excess in Children

Longitudinal growth results from multifactorial and complex processes that take place in the context of different genetic traits and environmental influences. Thus, in view of the difficulties in comprehension of the physiological mechanisms involved in the achievement of normal height, our ability to make a definitive diagnosis of GH impairment still remains limited. There is a myriad of controversial aspects in relation to GH deficiency, mainly related to diagnostic controversies and advances in molecular biology. This might explain the diversity in therapeutic responses and may also serve as a rationale for new "nonclassical" treatment indications for GH. It is necessary to acquire more effective tools to reach an adequate evaluation, particularly while considering the long-term implications of a correct diagnosis, the cost, and safety of treatments. On the other hand, overgrowth constitutes a heterogeneous group of different pathophysiological situations including excessive somatic and visceral growth. There are overlaps in clinical and molecular features among overgrowth syndromes, which constitute the real burden for an accurate diagnosis. In conclusion, both GH deficiency and overgrowth are a great dilemma, still not completely solved. In this chapter, we review the most burdensome aspects related to short stature, GH deficiency, and excess in children, avoiding any details about well-known issues that have been extensively discussed in the literature.

Orthopaedic manifestations of Proteus syndrome in a child with literature update

Background

Proteus syndrome is a rare developmental disorder of unknown aetiology. It is a disorder characterized by postnatal overgrowth affecting multiple tissues. Proteus syndrome is most frequently manifested in skeletal changes. As manifestations of Proteus syndrome are highly variable, and many are found in other overgrowth syndromes, and due to inconsistent application of diagnostic criteria, the literature has more reports of patients misdiagnosed than correctly diagnosed. The purpose of this study is to report the clinical and radiographic patterns of affection of the musculoskeletal system in Proteus syndrome in the light of the proposed diagnostic criteria and cases reported in the literature.

Methods

The clinical and radiographic musculoskeletal characteristics of a child with Proteus syndrome are illustrated along with a literature update. The orthopaedic manifestations in our patient are correlated to cases and proposed diagnostic criteria reported in the literature.

Results

The study of the presented case and review of available literature show that there tends to be a highly characteristic pattern of skeletal abnormalities in Proteus syndrome.

Conclusion

The rarity of Proteus syndrome and the variability of signs make the diagnosis challenging. Clinical and radiographic examinations are important contributors to the diagnosis. The clinical utility of the reported cases is significantly dependent on consistent application of diagnostic criteria that augment diagnostic accuracy.

The present case reinforces the need for supplementary musculoskeletal imaging modalities to be implemented in the diagnosis of Proteus syndrome.

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We presented the musculoskeletal manifestations of Proteus syndrome (PS) in a child.

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The rarity of PS and the variability of signs make the diagnosis challenging.

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There tends to be a characteristic pattern of skeletal abnormalities in patients with PS.

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The clinical utility of reported cases is dependent on valid diagnostic criteria.

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Inadequate clinical data in reported cases are likely to lead to misdiagnosis

Generalized overgrowth syndromes with prenatal onset

Children with generalized overgrowth syndromes are large at birth, or have excessive postnatal growth. Many of these syndromes are associated with an increase in neoplasia. Consideration of the possibility of overgrowth syndrome in a pediatric patient who presents with increased growth parameters, variable malformations and neurodevelopmental phenotype, and distinctive features, is important for medical management, reproductive counseling, and tumor surveillance for some of the disorders. This review describes the clinical features and surveillance recommendations for the common generalized overgrowth syndromes the pediatrician may encounter. It also provides a glimpse into advances of recent years in understanding the molecular mechanisms responsible for the disrupted growth regulation in these disorders.

Novel overgrowth syndrome phenotype due to recurrent de novo PDGFRB mutation

Using exome analysis, we identified a novel overgrowth syndrome arising from a mutation in PDGFRB, which plays a critical role in growth and differentiation. This entity is characterized by somatic overgrowth, distinctive facial features, hyperelastic and fragile skin, white matter lesions, and neurologic deterioration.

Malan syndrome: Sotos-like overgrowth with de novo NFIX sequence variants and deletions in six new patients and a review of the literature

De novo monoallelic variants in NFIX cause two distinct syndromes. Whole gene deletions, nonsense variants and missense variants affecting the DNA-binding domain have been seen in association with a Sotos-like phenotype that we propose is referred to as Malan syndrome. Frameshift and splice-site variants thought to avoid nonsense-mediated RNA decay have been seen in Marshall-Smith syndrome. We report six additional patients with Malan syndrome and de novo NFIX deletions or sequence variants and review the 20 patients now reported. The phenotype is characterised by moderate postnatal overgrowth and macrocephaly. Median height and head circumference in childhood are 2.0 and 2.3 standard deviations (SD) above the mean, respectively. There is overlap of the facial phenotype with NSD1-positive Sotos syndrome in some cases including a prominent forehead, high anterior hairline, downslanting palpebral fissures and prominent chin. Neonatal feeding difficulties and/or hypotonia have been reported in 30% of patients. Developmental delay/learning disability have been reported in all cases and are typically moderate. Ocular phenotypes are common, including strabismus (65%), nystagmus (25% ) and optic disc pallor/hypoplasia (25%). Other recurrent features include pectus excavatum (40%) and scoliosis (25%). Eight reported patients have a deletion also encompassing CACNA1A, haploinsufficiency of which causes episodic ataxia type 2 or familial hemiplegic migraine. One previous case had episodic ataxia and one case we report has had cyclical vomiting responsive to pizotifen. In individuals with this contiguous gene deletion syndrome, awareness of possible later neurological manifestations is important, although their penetrance is not yet clear.

Differential diagnoses of overgrowth syndromes: the most important clinical and radiological disease manifestations

Overgrowth syndromes comprise a heterogeneous group of diseases that are characterized by excessive tissue development. Some of these syndromes may be associated with dysfunction in the receptor tyrosine kinase (RTK)/PI3K/AKT pathway, which results in an increased expression of the insulin receptor. In the current review, four overgrowth syndromes were characterized (Proteus syndrome, Klippel-Trenaunay-Weber syndrome, Madelung's disease, and neurofibromatosis type I) and illustrated using cases from our institution. Because these syndromes have overlapping clinical manifestations and have no established genetic tests for their diagnosis, radiological methods are important contributors to the diagnosis of many of these syndromes. The correlation of genetic discoveries and molecular pathways that may contribute to the phenotypic expression is also of interest, as this may lead to potential therapeutic interventions.

Beckwith-Wiedemann syndrome with overlapping Perlman syndrome manifestation

Beckwith-Wiedemann syndrome (BWS) is an overgrowth syndrome known as exomphalos-macroglossia - gigantism syndrome. Prognosis is good, prenatal diagnosis is important for pregnancy management but might be difficult due to clinical overlap with other syndromes. Perlman syndrome is an overgrowth syndrome with high perinatal mortality, most frequent antenatal findings include polyhydramnios, macrosomia, visceromegaly, nephromegaly and foetal ascites. Authors present a case of prenatally diagnosed BWS with severe ascites as first antenatal finding and lethal course, signs more typical of Perlman syndrome. This combination of clinical signs has not been published yet and may contribute to specification of possible prenatal manifestation of BWS.

Genetic syndromes associated with overgrowth in childhood

Overgrowth syndromes comprise a diverse group of conditions with unique clinical, behavioral and molecular genetic features. While considerable overlap in presentation sometimes exists, advances in identification of the precise etiology of specific overgrowth disorders continue to improve clinicians' ability to make an accurate diagnosis. Among them, this paper introduces two classic genetic overgrowth syndromes: Sotos syndrome and Beckwith-Wiedemann syndrome. Historically, the diagnosis was based entirely on clinical findings. However, it is now understood that Sotos syndrome is caused by a variety of molecular genetic alterations resulting in haploinsufficiency of the NSD1 gene at chromosome 5q35 and that Beckwith-Wiedemann syndrome is caused by heterogeneous abnormalities in the imprinting of a number of growth regulatory genes within chromosome 11p15 in the majority of cases. Interestingly, the 11p15 imprinting region is also associated with Russell-Silver syndrome which is a typical growth retardation syndrome. Opposite epigenetic alterations in 11p15 result in opposite clinical features shown in Beckwith-Wiedemann syndrome and Russell-Silver syndrome. Although the exact functions of the causing genes have not yet been completely understood, these overgrowth syndromes can be good models to clarify the complex basis of human growth and help to develop better-directed therapies in the future.