Sotos syndrome with intestinal polyposis and pigmentary changes of the genitalia

Clinical Spectrum and Science Behind the Hamartomatous Polyposis Syndromes

The hamartomatous polyposis syndromes are a set of clinically distinct disorders characterized by the occurrence of hamartomatous polyps in the gastrointestinal tract. These syndromes include juvenile polyposis syndrome, Peutz-Jeghers syndrome, and PTEN hamartoma tumor syndrome. Although each of the syndromes has distinct phenotypes, the hamartomatous polyps can be challenging to differentiate histologically. Additionally, each of these syndromes is associated with increased lifetime risks of gene-specific and organ-specific cancers, including those outside of the gastrointestinal tract. Germline pathogenic variants can be identified in a subset of individuals with these syndromes, which facilitates molecular diagnosis and subsequent gene-enabled management in the setting of genetic counseling. Although the malignant potential of hamartomatous polyps remains elusive, timely recognition of these syndromes is important and enables presymptomatic cancer surveillance and management before symptom exacerbation. Presently, there are no standard agents to prevent the development of polyps and cancers in the hamartomatous polyposis syndromes.

Gastrointestinal manifestations in PTEN hamartoma tumor syndrome

The PTEN hamartoma tumor syndrome (PHTS) is a heterogeneous set of multisystem disorders caused by germline pathogenic variants in the PTEN tumor suppressor gene. Manifestations include developmental anomalies and proliferative lesions. Evidence of involvement of the GI tract has accrued over time, leading to the incorporation of GI manifestations (multiple hamartomas, glycogenic acanthosis and colorectal cancer) into the diagnostic criteria. Polyps of the upper and lower GI tract are found in most adult patients and in a significant fraction of children. Polyps tend to be of mixed histology, with a predominance of hamartomas and ganglioneuromas. PHTS patients are also at increased risk of colorectal cancer, and surveillance by colonoscopy is advised starting at the age of 35-40 years. A number of additional manifestations, including eosinophilic gastrointestinal disorders, have been observed in few or single cases, and their association with PHTS has yet to be determined.

PTEN hamartoma tumour syndrome: what happens when there is no PTEN germline mutation?

Hereditary cancer syndromes represent ~10% of all incident cancers. It is important to identify individuals having these disorders because, unlike patients with sporadic cancer, these patients require specialised life-long care, with implications for their families. Importantly, the identification of alterations in cancer-predisposing genes facilitates gene-informed molecular diagnosis, cancer risk assessment and gene-specific clinical management. Moreover, knowledge about gene function in the inherited cancers offers insights towards biological processes pertinent to the more common sporadic cancers. Conversely, without a known gene, clinical management is less precise, and it is impossible to offer predictive testing of family members. PTEN hamartoma tumour syndrome (PHTS) is an umbrella term encompassing four overgrowth and cancer predisposition disorders associated with germline PTEN mutations. With time, it became evident that only a finite subset of individuals with PHTS-associated phenotypes harbour germline PTEN mutations. Therefore, non-PTEN aetiologies exist in PTEN wildtype patients. Indeed, gene discovery efforts over the last decade elucidated multiple candidate cancer predisposition genes. While a subset of genes (e.g. AKT1, PIK3CA) are biologically plausible as being key effectors within the PTEN signalling cascade, other genes required meticulous functional interrogation to explain their contribution to PHTS-related phenotypes. Collectively, the extensive phenotypic heterogeneity of the clinical syndromes typically united by PTEN is reflected by the genetic heterogeneity revealed through gene discovery. Validating these gene discoveries is critical because, while PTEN wildtype patients can be diagnosed clinically, they do not have the benefit of specific gene-informed risk assessment and subsequent management.

PTEN in Hereditary and Sporadic Cancer

Germline pathogenic phosphatase and tensin homolog (PTEN) mutations cause PTEN hamartoma tumor syndrome (PHTS), characterized by various benign and malignant tumors of the thyroid, breast, endometrium, and other organs. Patients with PHTS may present with other clinical features such as macrocephaly, intestinal polyposis, cognitive changes, and pathognomonic skin changes. Clinically, deregulation of PTEN function is implicated in other human diseases in addition to many types of human cancer. PTEN is an important phosphatase that counteracts one of the most critical cancer pathways: the phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathways. Although PTEN can dephosphorylate lipids and proteins, it also has functions independent of phosphatase activity in normal and pathological states. It is positively and negatively regulated at the transcriptional level as well as posttranslationally by phosphorylation, ubiquitylation, oxidation, and acetylation. Although most of its tumor-suppressor activity is likely to be caused by lipid dephosphorylation at the plasma membrane, PTEN also resides in the cytoplasm and nucleus, and its subcellular distribution is under strict control. In this review, we highlight our current knowledge of PTEN function and recent discoveries in understanding PTEN function regulation and how this can be exploited therapeutically for cancer treatment.

PTEN Hamartoma tumor syndrome in childhood: A review of the clinical literature

PTEN hamartoma tumor syndrome (PHTS) is a highly variable autosomal dominant condition associated with intellectual disability, overgrowth, and tumor predisposition phenotypes, which often overlap. PHTS incorporates a number of historical clinical presentations including Bannayan-Riley-Ruvalcaba syndrome, Cowden syndrome, and a macrocephaly-autism/developmental delay syndrome. Many reviews in the literature focus on PHTS as an adult hamartoma and malignancy predisposition condition. Here, we review the current literature with a focus on pediatric presentations. The review starts with a summary of the main conditions encompassed within PHTS. We then discuss PHTS diagnostic criteria, and clinical features. We briefly address rarer PTEN associations, and the possible role of mTOR inhibitors in treatment. We acknowledge the limited understanding of the natural history of childhood-onset PHTS as a cancer predisposition syndrome and present a summary of important management considerations.

PTEN-opathies: from biological insights to evidence-based precision medicine

The tumor suppressor phosphatase and tensin homolog (PTEN) classically counteracts the PI3K/AKT/mTOR signaling cascade. Germline pathogenic PTEN mutations cause PTEN hamartoma tumor syndrome (PHTS), featuring various benign and malignant tumors, as well as neurodevelopmental disorders such as autism spectrum disorder. Germline and somatic mosaic mutations in genes encoding components of the PI3K/AKT/mTOR pathway downstream of PTEN predispose to syndromes with partially overlapping clinical features, termed the "PTEN-opathies." Experimental models of PTEN pathway disruption uncover the molecular and cellular processes influencing clinical phenotypic manifestations. Such insights not only teach us about biological mechanisms in states of health and disease, but also enable more accurate gene-informed cancer risk assessment, medical management, and targeted therapeutics. Hence, the PTEN-opathies serve as a prototype for bedside to bench, and back to the bedside, practice of evidence-based precision medicine.

Medical genetics and genomic medicine in the United States of America. Part 1: history, demographics, legislation, and burden of disease

Medical genetics and genomic medicine in the United States of America. Part 1: history, demographics, legislation, and burden of disease.

Commonest overgrowth syndromes

Overgrowth syndromes, although rare, are diagnosed more frequently lately. Major progress, such as the identification of genetic causes, has recently enhanced the delineation of the characteristic and noncharacteristic manifestations, phenotype-genotype correlations and knowledge of the underlying pathophysiologic mechanisms. This review provides a summary of the most important overgrowth syndromes aiming to familiarize the treating physician with the cardinal clinical features involved in these syndromes that encompass overgrowth, but also have a variety of other clinical manifestations (neurologic, musculoskeletal, skin, and accompanying tumors).

Ras and Rap signaling in synaptic plasticity and mental disorders

The Ras family GTPases (Ras, Rap1, and Rap2) and their downstream mitogen-activated protein kinases (ERK, JNK, and p38MAPK) and PI3K signaling cascades control various physiological processes. In neuronal cells, recent studies have shown that these parallel cascades signal distinct forms of AMPA-sensitive glutamate receptor trafficking during experience-dependent synaptic plasticity and adaptive behavior. Interestingly, both hypo- and hyperactivation of Ras/ Rap signaling impair the capacity of synaptic plasticity, underscoring the importance of a "happy-medium" dynamic regulation of the signaling. Moreover, accumulating reports have linked various genetic defects that either up- or down-regulate Ras/Rap signaling with several mental disorders associated with learning disability (e.g., Alzheimer's disease, Angelman syndrome, autism, cardio-facio-cutaneous syndrome, Coffin-Lowry syndrome, Costello syndrome, Cowden and Bannayan-Riley-Ruvalcaba syndromes, fragile X syndrome, neurofibromatosis type 1, Noonan syndrome, schizophrenia, tuberous sclerosis, and X-linked mental retardation), highlighting the necessity of happy-medium dynamic regulation of Ras/Rap signaling in learning behavior. Thus, the recent advances in understanding of neuronal Ras/Rap signaling provide a useful guide for developing novel treatments for mental diseases.

Hamartomatous polyposis syndromes

Hamartomatous polyposis syndromes are a diverse group of inherited conditions grouped together because they exhibit hamartomatous rather than epithelial polyp histology. Each syndrome exhibits characteristic polyp histology, gastrointestinal polyp distribution, gastrointestinal cancer risks, extra-intestinal benign findings and often extra-intestinal cancer risks. Identifying individuals at risk for these syndromes and accurately defining the precise diagnosis are necessary for planning surveillance and management in order to prevent the benign and malignant complications. Characteristic syndrome features including gastrointestinal findings, pathology, genetics, and management options for the three most common hamartomatous polyposis syndromes, Peutz-Jeghers syndrome, PTEN hamartoma tumour syndrome, and juvenile polyposis will be presented in this review.

Hamartomatous polyposis syndromes

Since the histologic description of the hamartomatous polyp in 1957 by Horrilleno and colleagues, descriptions have appeared of several different syndromes with the propensity to develop these polyps in the upper and lower gastrointestinal tracts. These syndromes include juvenile polyposis, Peutz-Jeghers syndrome, hereditary mixed polyposis syndrome, and the phosphatase and tensin homolog gene (PTEN) hamartoma tumor syndromes (Cowden and Bannayan-Riley-Ruvalcaba syndromes), which are autosomal-dominantly inherited, and Cronkhite-Canada syndrome, which is acquired. This article reviews the clinical aspects, the molecular pathogenesis, the affected organ systems, the risks of cancer, and the management of these hamartomatous polyposis syndromes. Although the incidence of these syndromes is low, it is important for clinicians to recognize these disorders to prevent morbidity and mortality in these patients, and to perform presymptomatic testing in patients at risk.

PTEN hamartomatous tumor syndromes (PHTS): rare syndromes with great relevance to common cancers and targeted drug development

Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) is a tumor suppressor gene located on chromosome 10q22-23 that negatively regulates the pro-survival PI3K/Akt/mTOR pathway by functioning as a lipid phosphatase. Signaling through this pathway promotes cellular transformation and survival as well as resistance to chemotherapy and radiation. Loss of PTEN function is commonly observed in human cancers through somatic mutation, hypermethylation, and/or enhanced degradation. PTEN hamartomatous tumor syndromes (PHTS) are a collection of rare clinical syndromes marked by germline PTEN loss. Compared to the general population, PHTS patients have an increased risk of developing certain cancers and can develop benign tumors in virtually any organ. These patients provide a unique opportunity to examine the role of PTEN in human tumorigenesis, as well as study genotype-phenotype relationships. Because these patients are at higher risk of developing malignancies and have no established medical therapies, early screening, surveillance, and preventive care are important issues. Inhibitors of the PI3K/Akt/mTOR pathway that are being developed as cancer therapeutics could provide new therapeutic options for these rare patients, and could be credentialed as pathway inhibitors prior to testing in the general oncology population.

Phosphoinositide phosphatases in a network of signalling reactions

Phosphoinositide phosphatases dephosphorylate the three positions (D-3, 4 and 5) of the inositol ring of the poly-phosphoinositides. They belong to different families of enzymes. The PtdIns(3,4)P(2) 4-phosphatase family, the tumour suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN), SAC1 domain phosphatases and myotubularins belong to the tyrosine protein phosphatases superfamily. They share the presence of a conserved cysteine residue in the consensus CX(5)RT/S. Another family consists of the inositol polyphosphate 5-phosphatase isoenzymes. The importance of these phosphoinositide phosphatases in cell regulation is illustrated by multiple examples of their implications in human diseases such as Lowe syndrome, X-linked myotubular myopathy, cancer, diabetes or bacterial infection.

Hamartomatous polyps of the colon: ganglioneuromatous, stromal, and lipomatous

Intestinal ganglioneuromas comprise benign, hamartomatous polyps characterized by an overgrowth of nerve ganglion cells, nerve fibers, and supporting cells in the gastrointestinal tract. This polyposis has been divided into 3 subgroups, each with a different degree of ganglioneuroma formation: polypoid ganglioneuroma, ganglioneuromatous polyposis, and diffuse ganglioneuromatosis. The ganglioneuromatous polyposis subgroup is not known to coexist with systemic disorders that often have an associated intestinal polyposis, such as multiple endocrine neoplasia type IIb, neurofibromatosis type I, and Cowden syndrome. We report a case of ganglioneuromatous polyposis plus cutaneous lipomatosis in a 41-year-old man with no established systemic disease. However, he possessed unique anatomic findings in addition to his ganglioneuromatosis, suggesting that the ganglioneuromatosis-lipomatosis in our patient may represent an unrecognized syndrome. This case report and brief review of the literature provide an overview of intestinal ganglioneuromatosis in relation to the hereditary polyposis syndromes and describe the individual ganglioneuromatosis subgroups.

Sotos syndrome

Sotos syndrome is an autosomal dominant condition characterised by a distinctive facial appearance, learning disability and overgrowth resulting in tall stature and macrocephaly. In 2002, Sotos syndrome was shown to be caused by mutations and deletions of NSD1, which encodes a histone methyltransferase implicated in chromatin regulation. More recently, the NSD1 mutational spectrum has been defined, the phenotype of Sotos syndrome clarified and diagnostic and management guidelines developed.

Cutaneous lipoma in children: 5 cases with Bannayan-Riley-Ruvalcaba syndrome

Cutaneous lipoma is rare in children, but it can be part of a syndrome such as the Bannayan-Riley-Ruvalcaba syndrome (BRRS). The BRRS is a dominant autosomal disorder characterized by cutaneous lipomas, macrocephaly, intestinal polyps, and developmental delay associated with PTEN gene mutations. This syndrome is thought to represent a pediatric form of the Cowden syndrome, characterized among other features by an increased risk of cancer. We report 5 cases of BRRS, all diagnosed in children with lipoma and macrocephaly. Children presenting with lipomas need a complete physical examination to look for other signs of BRRS, because they may need further follow-up for tumor screening in adulthood.

The hamartomatous polyposis syndromes: a clinical and molecular review

Inherited forms of gastrointestinal cancer have been a major focus of study and advancement over the past decade. Familial adenomatous polyposis and hereditary nonpolyposis colon cancer are the two most common heritable colon cancer syndromes. Inherited polyposis syndromes are characterized by the dominant type of polyp (whether adenomatous or hamartomatous) present and by the polyp's location within the gastrointestinal tract. The hamartomatous polyposis syndromes are characterized by an overgrowth of cells native to the area in which they normally occur. They represent a small but appreciable number of the gastrointestinal inherited cancer predisposition syndromes; it is now known that many of these syndromes carry a substantial risk for developing colon cancer as well as other gastrointestinal and pancreatic cancers. Patients afflicted with these syndromes are also at significant risk for extraintestinal malignancies. Seven inherited hamartomatous polyposis syndromes have been described: familial juvenile polyposis syndrome, Cowden's syndrome, Bannayan-Ruvalcaba-Riley syndrome, Peutz-Jeghers syndrome, basal cell nevus syndrome, neurofibromatosis 1, and multiple endocrine neoplasia syndrome 2B. Hereditary mixed polyposis syndrome is a variant of juvenile polyposis characterized by both hamartomatous and adenomatous polyps. The hamartomatous syndromes occur at approximately 1/10th the frequency of the adenomatous syndromes and account for <1% of colorectal cancer in Northern America. While the diagnosis of these inherited syndromes is primarily clinical, genetic testing is now available for all six syndromes. However, there are a significant number of spontaneous mutations seen in each of the syndromes. The management of these patients necessitates a coordinated multidisciplinary approach. The purpose of this review is to characterize the clinical and pathological features of these syndromes and to review the targets of cancer surveillance. The molecular alterations responsible for the inherited hamartomatous polyposis syndromes will also be discussed.

Molecular dimensions of gastrointestinal tumors: some thoughts for digestion

Topics discussed here include PTEN mutations and colonic polyps; WNT signaling, APC, beta-catenin, and gastrointestinal neoplasms; mismatch-repair genes (MLH1, MSH2, PMS1, MSH6) and hereditary nonpolyposis colorectal cancer; MYH mutations and autosomal recessive colorectal tumors; STK11 mutations and Peutz-Jeghers syndrome; TGFbeta and gastrointestinal cancer; BMPR1A mutations and juvenile polyposis; FGF/FGFR alterations in gastrointestinal neoplasms; PTCH mutations and gastrointestinal neoplasms; RUNX3 expression and gastric cancer; role of mucins in gastric carcinogenesis; KIT, PDGFRalpha, and gastrointestinal stromal tumors; intestinal neurofibromatosis; and gastrointestinal tumors in other disorders.

Bannayan-Riley-Ruvalcaba syndrome: further delineation of the phenotype and management of PTEN mutation-positive cases

Bannayan-Riley-Ruvalcaba syndrome (BRRS) is characterised by macrocephaly, intestinal hamartomatous polyps, lipomas, pigmented maculae of the glans penis, developmental delay and mental retardation. The syndrome follows an autosomal dominant pattern of inheritance. In 1997 reports on two BRRS patients with a deletion at 10q23.2-q24.1 were published. In the same year, the first two families with BRRS and a mutation of the PTEN gene were reported. Mutations in the PTEN gene have also been demonstrated in patients with Cowden syndrome (CS), which shows partial clinical overlap with BRRS, and in families with cases both of BRRS and CS. PTEN mutation positive BRRS and CS are likely to be different phenotypic presentations of the same syndrome. If BRRS and CS are one single condition, the question arises whether patients with BRRS should be screened for malignant tumours, since patients with Cowden syndrome have an increased risk of breast, endometrial, thyroid and renal cancer. We present two isolated cases and one family and confirm that BRRS and CS are allelic. Furthermore, we review the PTEN mutation positive BRRS cases, to further delineate the phenotype and to compare the cases with a genomic deletion with the cases with a point mutation. We recommend offering BRRS cases with a mutation in PTEN the same surveillance protocol for (malignant) tumours as is currently recommended for CS. In addition, we propose a yearly haemoglobin test from early infancy for the early detection of intestinal hamartomas, which are likely to give severe complications, especially in BRRS cases.

Genetic conditions associated with intestinal juvenile polyps

Juvenile polyps are hamartomatous polyps found primarily in infants and children, and in association with juvenile polyposis (JP; OMIM #174900), Cowden syndrome (CS; OMIM #158350), and Bannayan-Riley-Ruvalcaba syndrome (BRRS; OMIM# 153480). Although solitary juvenile polyps are benign lesions, when present in JP patients they may lead to gastrointestinal cancers. Germline mutations in MADH4 and BMPR1A predispose to JP, and both genes are involved in TGF-beta superfamily signaling pathways. In CS and BRRS, juvenile polyps are a less consistent feature, and CS patients are at risk for breast and thyroid cancers. Mutations of the tumor suppressor gene PTEN have been found in the germline of both CS and BRRS patients. Despite different underlying genetic mechanisms, these and other syndromes share the same phenotypic feature of juvenile polyps.

[Macrocephaly and multiple hamartoma: a very variable entity]

The Bannayan-Zonana is a dominant autosomal polymalformation syndrome.

CASE REPORT

We report a case of Bannayan-Zonana syndrome in a 3-year-old girl, who presented with macrocephaly and a cervical lipoma. The patient's mother had neurofibromatosis I. No mutation in the PTEN gene was found. The slowly progressive lipoma increased with age and the surgical reduction was necessary.

COMMENTARIES

Macrocephaly is constant in different syndromes characterized with multiple hamartomas. The multiple hamartomas syndrome represents an entity with a high variability of expression.

Hamartomatous polyposis syndromes: molecular genetics, neoplastic risk, and surveillance recommendations

Hamartomatous polyposis syndromes are characterized by an overgrowth of cells or tissues native to the area in which they normally occur. Juvenile polyposis syndrome (JPS) results from germ-line mutations in the SMAD-4 gene (18q21.1) that encodes for an enzyme involved in transforming growth factor beta(TGF-beta) signal transduction. The increased neoplastic risk may result from SMAD-4 mutations in the stromal component, which stimulate epithelial dysplasia and progression to invasive malignancy. Peutz-Jeghers syndrome (PJS) is associated with germ-line mutations in the LKB1 gene (19p13.3) that encodes a multifunctional serine-threonine kinase. These mutations occur in the epithelial component, suggesting a direct tumor suppressor effect. Patients are at an increased risk of intestinal and extraintestinal malignancies, including breast, pancreatic, ovarian, testicular, and cervical cancer. Cowden's disease is associated with germ-line mutations in the PTEN gene (10q22-23) and an increased risk of breast and thyroid malignancies. Ruvalcaba-Myhre-Smith syndrome is less common; controversy suggests that it may represent a variant of Cowden's disease.

CONCLUSIONS

Genetic alterations underlying hamartomatous polyposis syndromes are diverse. Carcinogenesis may result from either germ-line mutations in the stroma (JPS) or as a direct result of functional deletion of tumor suppressor genes (PJS). Diagnosis depends on clinical presentation and patterns of inheritance within families. Suggested surveillance guidelines for the proband and first-degree relatives are outlined.

Bannayan-Riley-Ruvalcaba syndrome: report of a family

Bannayan-Riley-Ruvalcaba (BRR) syndrome is a rare inherited condition. We describe the protean orofacial manifestations of this syndrome in one family and consider their management. The dental surgeon should be aware of this entity, its orofacial connotations and the possible association with Cowden's syndrome.

Identification of a PTEN mutation in a family with Cowden syndrome and Bannayan-Zonana syndrome

Cowden syndrome (CS) and Bannayan-Zonana syndrome (BZS) are two inherited hamartoma syndromes characterized by distinct phenotypic features. Mutations in the PTEN gene have been identified in patients with CS and BZS, suggesting the presence of a common genetic basis. We describe a single kindred with individuals manifesting both CS and BZS phenotypes (CS/BZS overlap family) in which we have identified a novel mutation in PTEN by DNA sequencing. We have confirmed these results by means of restriction enzyme analysis. The presence of individuals with CS and BZS within the same family, and moreover the identification of identical PTEN gene mutations in these individuals, suggest that these two syndromes represent different phenotypic expressions of one disease. Furthermore, these findings imply that, like patients with CS, individuals with BZS should be monitored for the onset of malignancy.

Identification of PTEN mutations in five families with Bannayan-Zonana syndrome

Germline mutations in PTEN, a putative tumor suppressor gene, has been identified in 2 autosomal dominant inherited hamartoma syndromes, Cowden syndrome (CS) and Bannayan-Zonana syndrome (BZS). While both diseases exhibit distinct phenotypic features, there seems to be a partial clinical overlap between the 2 diseases. To date, 9 families with BZS have been screened for PTEN mutations, of which 5 were found to exhibit mutations in this gene. We report 5 novel germline mutations in the PTEN coding sequence from 5 unrelated families with the BZS phenotype. While all the mutations we identified are novel in BZS, 1003C-->T (nonsense mutation) and 209+5G-->A (putative splice site mutation) have been previously reported in unrelated families with CS and Lhermitte Duclos disease. Interestingly, 1 of the families has an individual with BZS and 1 with CS phenotype, associated with a single PTEN mutation, 885insA. These data support the notion that CS and BZS may be within the spectrum of the same primary disorder.

Inherited macrocephaly-hamartoma syndromes

Recent discoveries in the molecular biology of the phosphatase and tensin homolog (PTEN) locus in the q22-23 region of chromosome 10 prove and/or suggest that several syndromes previously considered to be clinically and genetically distinct entities should actually be unified into a single entity. This conclusion is most secure for the Cowden and "Bannayan-Zonana" phenotypes, but almost certainly should also include the "Riley-Ruvalcaba" and Lhermitte-Duclos phenotypes as well benign familial macrocephaly and external hydrocephalus. The clinical and molecular data supporting this unification are presented along with a proposal for new nomenclature-the PTEN MATCHS (macrocephaly, autosomal dominant, thyroid disease, cancer, hamartomata, skin abnormalities) syndrome-based on the observed clinical abnormalities.

The syndromes of Sotos and Weaver: reports and review

The syndromes of Sotos and Weaver are paradigmatic of the daily nosologic difficulties faced by clinical geneticists attempting to diagnose and counsel, and to give accurate prognoses in cases of extensive phenotypic overlap between molecularly undefined entities. Vertebrate development is constrained into only very few final or common developmental paths; therefore, no developmental anomaly seen in humans is unique to ("pathognomonic" of) one syndrome. Thus, it is not surprising that prenatal overgrowth occurs in several syndromes, including the Sotos and Weaver syndromes. Are they sufficiently different in other respects to allow the postulation of locus (rather than allele) heterogeneity? Phenotypic data in both conditions are biased because of ascertainment of propositi, and the apparent differences between them may be entirely artificial as they were between the G and BBB syndromes. On the other hand, the Sotos syndrome may be a cancer syndrome, the Weaver syndrome not (though a neuroblastoma was reported in the latter); in the former there is also remarkably advanced dental maturation rarely commented on in the latter. In Weaver syndrome there are more conspicuous contractures and a facial appearance that experts find convincingly different from that of Sotos individuals. Nevertheless, the hypothesis of locus heterogeneity is testable; at the moment we are inclined to favor the hypothesis of allele heterogeneity. An international effort is required to map, isolate, and sequence the causal gene or genes.

Megalencephaly, mega corpus callosum, and complete lack of motor development: a previously undescribed syndrome

We report on 3 sporadic cases of in utero onset megalencephaly. Children were born to healthy nonconsanguineous parents after uneventful pregnancies. Head circumferences were just above the 97th centile at birth in 2 patients, 2 cm above the 97th centile in 1 patient, and subsequently increased to 4.5-6.5 cm above the 97th centile at age 5 years. All patients completely lacked motor and speech development and showed very little intellectual progress. There was a distinctive facial aspect with frontal bossing, low nose bridge, and large eyes, but no cutaneous abnormalities and no signs of other organ involvement. Magnetic resonance imaging showed bilateral megalencephaly with a broad corpus callosum, enlarged white matter, and focally thick gray matter, resulting in pachygyric appearance of the cortex. Opercularization was incomplete, and the Sylvian fissures were wide. Somatosensory evoked potentials in 1 patient showed normal latencies of cervical and contracortical potentials but bilaterally increased cortical amplitudes. To the best of our knowledge, no similar case observations have been recorded previously.

Cutaneous vascular anomalies. Part I. Hamartomas, malformations, and dilation of preexisting vessels

Classification of cutaneous vascular anomalies is difficult because conceptual confusion persists between vascular neoplasms and malformations. However, hemangiomas of the infancy fulfill criteria both for hyperplasia and neoplasm because they result from proliferation of endothelial cells, but often undergo complete regression. Despite these pitfalls we have classified cutaneous vascular anomalies into the following categories: hamartomas, malformations, dilatations of preexisting vessels, hyperplasias, benign neoplasms, and malignant neoplasms. In this first part of our clinicopathologic review of vascular anomalies, hamartomas, malformations, and dilatation of preexisting vessels are covered. Hamartomas include several combined vascular and melanocytic proliferations grouped as phakomatosis pigmentovascularis and the so-called eccrine angiomatous hamartoma that consists of proliferations of both eccrine glands and blood vessels. Vascular malformations result from anomalies of embryologic development, and in some of them the abnormalities of the involved vessels are more functional than anatomic, as is the case of nevus anemicus. In contrast, other cutaneous vascular malformations show striking morphologic abnormalities of the vascular structures. These anatomic vascular malformations are subdivided into the following groups: capillary, venous, arterial, lymphatic, and combined anomalies. Spider angioma, capillary aneurysm-venous lake, and telangiectases are not vascular proliferations at all, but dilations of preexisting vessels. In our opinion, most of the lesions described with the generic term of "angiokeratoma" are not authentic vascular neoplasms, but hyperkeratotic malformations of capillaries and venules or acquired telangiectases of preexisting blood vessels of the papillary dermis. Therefore the first group of these "angiokeratomas" are included in the vascular malformations section, and the second group are covered in the section of dilation of preexisting vessels. Lymphangiectases are considered the lymphatic counterpart of angiokeratomas because they result from ectasia of preexisting lymphatic vessels of the papillary dermis.

The clinical spectrum of long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency

Four patients with long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency are presented. Clinical onset in the form of acute encephalopathy occurred between the ages of 9 months and 3 years. The clinical course included recurrent metabolic crises in 4 patients, cardiac involvement and retinopathy in 3, and myopathy in 2. None had signs of peripheral neuropathy. Three patients died and one is currently well. Hypoketotic hypoglycemia with C6-C14 3-hydroxy-dicarboxylic aciduria during metabolic crises associated with decreased plasma carnitine levels was the main biochemical finding. Enzymologic studies disclosed long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency in all patients. Homozygosity for a G to C mutation at position 1528 in the encoding region of the enzyme was found in 2 patients. Histologic and electron microscopic studies of liver biopsy specimens revealed steatosis in 3 patients and mitochondrial abnormalities in 2. Skeletal muscle biopsies disclosed nonspecific degenerative changes in 2 patients and were normal in the remaining 2. Ultrastructural abnormalities in mitochondria were found in 3 patients. A review of the literature combined with the data from our series (total 22 patients) disclosed acute clinical onset in 77% of cases and subacute in 23%. In the combined series, the average age at onset was 11 months, family history was positive in 32% of patients and overall mortality was 50%. We describe the clinical spectrum of this disease and emphasize that, among patients with suspected beta-oxidation defects the finding of pigmentary retinopathy should lead to the suspicion of long-chain 3-hydroxyacyl-coenzyme A-dehydrogenase deficiency.

Sotos syndrome: a study of the diagnostic criteria and natural history

Seventy-nine patients with a provisional diagnosis of Sotos syndrome were clinically assessed, and their photographs between the ages of 1 and 6 years evaluated. These photographs, together with photographs of first degree relatives, also at ages 1 to 6 years, were reviewed by four clinical geneticists. Forty-one probands (but no first degree relatives) were identified in whom the facial gestalt was thought to be characteristic of Sotos syndrome. Comparison of anthropometric measurements, bone age, and developmental delay in these 41 probands showed marked differences between them and the remaining 38 probands, and allowed the formulation of guidelines for the diagnosis of Sotos syndrome. Length was identified as the most significantly increased prenatal parameter. In childhood occipitofrontal head circumference (OFC), height, and weight were all increased. OFC remained above the 97th centile in all but one case throughout childhood and adulthood, whereas height and weight had a tendency to return towards the mean. This 'normalisation' was more pronounced in females and was probably related to their early puberty. Early developmental delay and an advanced bone age, seen in 100% and 84% respectively of study cases, may be invariable in Sotos syndrome, but selection bias and limited data prevented confirmation of this supposition. The authors suggest that facial gestalt, growth pattern, bone age, and developmental delay are the major diagnostic criteria. Using these criteria, no affected first degree relatives were identified. There were few long term medical complications in the probands, but behavioural difficulties caused considerable parental concern.

Childhood onset autosomal dominant polycystic kidney disease in sibs: clinical picture and recurrence risk. German Working Group on Paediatric Nephrology (Arbeitsgemeinschaft für Pädiatrische Nephrologie

In a systematic study on the clinical picture and genetics of cystic kidneys in children, in association with the German working group on paediatric nephrology (Arbeitsgemeinschaft für Pädiatrische Nephrologie), we have investigated 79 children with early manifestation of autosomal dominant polycystic kidney disease (ADPKD). They belonged to 64 families (64 index patients and 15 affected sibs). Early manifestation was defined in this study as clinical symptoms (hypertension, proteinuria, impaired renal function, palpably enlarged kidneys) occurring before the age of 15 years. In order to estimate the recurrence risk to sibs of a previously diagnosed patient with early manifesting ADPKD, we found that 15 out of a total of 65 sibs of the 64 index patients (45% of the theoretically expected 32.5 gene carriers) showed comparable early manifestation. Another 10 symptom free children were diagnosed sonographically as having ADPKD before the age of 18 years, so that the total number of affected sibs was 25/65 in the study group, representing 76% of the gene carriers. Although the gene in childhood manifesting ADPKD can be transmitted through both sexes, a statistically significant (p < 0.05) maternal predominance was observed (M:F = 23:41). In affected sibs ages of onset, initial presentation, and the development of complications appeared to be similar in the majority of families. Our data indicate a high recurrence risk to sibs for early manifestation of ADPKD which has important implications for genetic counselling and clinical care of affected families and gives clues to the underlying genetic mechanism of childhood onset ADPKD.

Dominantly inherited megalencephaly, muscle weakness, and myoliposis: a carnitine-deficient myopathy within the spectrum of the Ruvalcaba-Myhre-Smith syndrome

We report 27 children, aged 14 months to 9 years, who had megalencephaly, hypotonia, proximal muscle weakness, speech and motor delay, and increased intracellular lipid (myoliposis) in needle muscle biopsy specimens. The patients had many features of the Ruvalcaba-Myhre-Smith syndrome, and in 17 families we confirmed the autosomal dominant inheritance pattern previously suggested. Muscle carnitine content was low in all 11 patients and all 4 affected relatives tested. All 27 probands were treated with oral L-carnitine; a clinical response was noted in 17. We speculate that myoliposis may be found in other disorders with megalencephaly and muscle symptoms. In such cases, muscle carnitine deficiency should be considered. The reason for the reduced muscle carnitine content is not known.

Macrosomia, obesity, macrocephaly and ocular abnormalities (MOMO syndrome) in two unrelated patients: delineation of a newly recognized overgrowth syndrome

We describe 2 unrelated patients, a boy and a girl, with an overgrowth syndrome and the following common characteristics: macrocrania, obesity, ocular abnormalities (retinal coloboma and nystagmus), downward slant of palpebral fissures, mental retardation, and delayed bone maturation. Both cases are of sporadic occurrence with no consanguinity between the parents. We suggest that this syndrome is due to a new autosomal dominant mutation and propose to designate it with the acronym of "MOMO syndrome" (Macrosomia, Obesity, Macrocrania, Ocular anomalities.