Prenatal and Neonatal Ultrasound and Magnetic Resonance Imaging Diagnosis of Sprengel's Deformity with Unusual Associations.

INTRODUCTION: Sprengel's deformity is a rare congenital anomaly of the shoulder rim. It is the most common congenital anomaly of the shoulder, associated with cosmetic deformity and abnormal shoulder function. Nonsurgical management can be considered for mild cases. Surgical intervention is indicated in moderate to severe cases with the goal of improving cosmetic appearance and function. The best surgical results are obtained in children aged 3-8 years. Correct diagnosis is very important because Sprengel's deformity can be accompanied by additional abnormalities, even in mild cases, and lack of a diagnosis delays proper treatment of the child. The severity of the defect may progress, so it is important to correctly identify children with Sprengel's deformity, even those with a mild form of the defect. CASE PRESENTATION: We report a case of prenatal sonographic diagnosis of Sprengel's deformity with additional features, as yet undescribed and missed - although visible - on prenatal magnetic resonance imaging (MRI). Cesarean delivery was performed due to preterm rupture of membranes, and a postnatal MRI confirmed the unusual constellation of Sprengel's anomaly with lateral meningocele, vestigial posterior meningocele, and lipoma tethering of the cord to the dural sac at the cervical-thoracic junction. CONCLUSION: Diagnosis of Sprengel's deformity is possible with prenatal ultrasound. Asymmetry of the cervical spine, discontinuity of the vertebral arch and abnormal vertebral bodies, as well as the asymmetric position of the shoulder blades with the presence of an omovertebral bone are signs that can help diagnose the defect.

Application of array comparative genomic hybridization (aCGH) for identification of chromosomal aberrations in the recurrent pregnancy loss.

Spontaneous abortion occurs in 8-20% of recognized pregnancies and usually takes place in the first trimester (7-11 weeks). There are many causes of pregnancy loss, but the most important (about 75%) is the presence of chromosomal aberrations. We present the results of oligonucleotide array application in a cohort of 62 miscarriage cases. The inclusion criteria for the study were the loss after 8th week of pregnancy and the appearance of recurrent miscarriages. DNA was extracted from trophoblast or fetal skin fibroblasts. In the 62 tested materials from recurrent miscarriages, the detection rate was 56.5% (35/62). The most commonly found were aneuploidies (65%) (chromosomal trisomy 14, 16, 18, 21, and 22), Turner syndrome, and triploidy (17.1%). Other chromosomal abnormalities included pathogenic and likely pathogenic structural aberrations: 1) pathogenic: deletion 7p22.3p12.3 and duplication 9p24.3p13.2 inherited from the normal father, deletion 3q13.31q22.2 and deletion 3q22.3q23 of unknown inheritance and duplication of 17p12 inherited from father with foot malformation; 2) likely pathogenic variants: deletion 17p13.1 inherited from normal mother, deletion 5q14.3 of unknown inheritance and de novo deletion 1q21.1q21.2. Among these aberrations, six CNVs (copy number variants) were responsible for the miscarriage: deletion 7p22.3p12.3 and duplication 9p24.3p13.2, deletion 3q13.31q22.2 and deletion 3q22.3q23, and deletion 17p13.1 and deletion 1q21.1q21.2. Other two findings were classified as incidental findings (deletion 5q14.3 and 17p12 duplication). Our research shows that 17% of the aberrations (6/35 abnormal results) that cannot be identified by the routine kariotype analysis are structural aberrations containing genes important for fetal development, the mutations of which may cause spontaneous abortion.

Interfamilial clinical variability in four Polish families with cranioectodermal dysplasia and identical compound heterozygous variants in WDR35.

Cranioectodermal dysplasia (CED) is a rare autosomal recessive disorder primarily characterized by craniofacial, skeletal, and ectodermal abnormalities. CED is a chondrodysplasia, which is part of a spectrum of clinically and genetically heterogeneous diseases that result from disruptions in cilia. Pathogenic variants in genes encoding components of the ciliary transport machinery are known to cause CED. Intra- and interfamilial clinical variability has been reported in a few CED studies and the findings of this study align with these observations. Here, we report on five CED patients from four Polish families with identical compound heterozygous variants [c.1922T>G p.(Leu641Ter) and c.2522A>T; p.(Asp841Val)] in WDR35. The frequent occurrence of both identified changes in Polish CED families suggests that these variants may be founder mutations. Clinical evaluation of the CED patients revealed interfamilial clinical variability among the patients. This includes differences in skeletal and ectodermal features as well as variability in development, progression, and severity of renal and liver insufficiency. This is the first report showing significant interfamilial clinical variability in a series of CED patients from unrelated families with identical compound heterozygous variants in WDR35. Our findings strongly indicate that other genetic and non-genetic factors may modulate the progression and expression of the patients' phenotypes.

Null variants in AGRN cause lethal fetal akinesia deformation sequence.

We present a case of lethal fetal akinesia deformation sequence (FADS) caused by a frameshift variant in trans with a 148 kbp deletion encompassing 3-36 exons of AGRN. Pathogenic variants in AGRN have been described in families with a form of congenital myasthenic syndrome (CMS), manifesting in the early childhood with variable fatigable muscle weakness. To the best of our knowledge, this is the first case of FADS caused by defects in AGRN gene. FADS has been reported to be caused by pathogenic variants in genes previously associated with CMS including these involved in endplate development and maintenance: MuSK, DOK7, and RAPSN. FADS seems to be the most severe form of CMS. None of the reported in the literature CMS cases associated with AGRN had two null variants, like the case presented herein. This indicates a strong genotype-phenotype correlation.

Prenatal genetic diagnosis of cranioectodermal dysplasia in a Polish family with compound heterozygous variants in WDR35.

The ciliary chondrodysplasias represent a group of clinically and genetically heterogeneous disorders that affect skeleton development. Cilia are organelles that project from the surface of many cell types and play an important role during prenatal and postnatal human development. Cranioectodermal dysplasia (Sensenbrenner syndrome, CED) is a ciliopathy primarily characterized by craniofacial, skeletal, and ectodermal abnormalities. To date six genes have been associated with CED: IFT122, WDR35, WDR19, IFT140, IFT43, and IFT52. Prenatal diagnosis of CED is challenging, and genetic testing can facilitate making a correct diagnosis. Here, we report on a family with two male siblings affected by CED: a 3.5 year-old patient and his 2 year-old brother. Molecular analysis of the proband at 1 year of age revealed compound heterozygous variants in WDR35: c.3G>A [p.(Met1-Ala30delinsMetfsTer4)] and c.2522A>T [p.(Asp841Val)]. Ultrasound examination during the second pregnancy revealed an increased nuchal translucency of 4.5 mm and a hypoplastic nasal bone at 12 weeks of gestation. Prenatal diagnostic testing was offered because of an increased risk for chromosomal abnormalities and recurrence risk for CED. Prenatal genetic analysis of a chorionic villus sample detected the WDR35 variants previously identified in the elder brother. This is the first report of a prenatal genetic diagnosis in CED.

Mapping of breakpoints in balanced chromosomal translocations by shallow whole-genome sequencing points to EFNA5, BAHD1 and PPP2R5E as novel candidates for genes causing human Mendelian disorders.

BACKGROUND: Mapping the breakpoints in de novo balanced chromosomal translocations (BCT) in symptomatic individuals provides a unique opportunity to identify in an unbiased way the likely causative genetic defect and thus find novel human disease candidate genes. Our aim was to fine-map breakpoints of de novo BCTs in a case series of nine patients. METHODS: Shallow whole-genome mate pair sequencing (SGMPS) together with long-range PCR and Sanger sequencing. In one case (BCT disrupting BAHD1 and RET) cDNA analysis was used to verify expression of a fusion transcript in cultured fibroblasts. RESULTS: In all nine probands 11 disrupted genes were found, that is, EFNA5, EBF3, LARGE, PPP2R5E, TXNDC5, ZNF423, NIPBL, BAHD1, RET, TRPS1 and SLC4A10. Five subjects had translocations that disrupted genes with so far unknown (EFNA5, BAHD1, PPP2R5E, TXNDC5) or poorly delineated impact on the phenotype (SLC4A10, two previous reports of BCT disrupting the gene). The four genes with no previous disease associations (EFNA5, BAHD1, PPP2R5E, TXNDC5), when compared with all human genes by a bootstrap test, had significantly higher pLI (p<0.017) and DOMINO (p<0.02) scores indicating enrichment in genes likely to be intolerant to single copy damage. Inspection of individual pLI and DOMINO scores, and local topologically associating domain structure suggested that EFNA5, BAHD1 and PPP2R5E were particularly good candidates for novel disease loci. The pathomechanism for BAHD1 may involve deregulation of expression due to fusion with RET promoter. CONCLUSION: SGMPS in symptomatic carriers of BCTs is a powerful approach to delineate novel human gene-disease associations.

PIGT-CDG, a disorder of the glycosylphosphatidylinositol anchor: description of 13 novel patients and expansion of the clinical characteristics.

PURPOSE: To provide a detailed electroclinical description and expand the phenotype of PIGT-CDG, to perform genotype-phenotype correlation, and to investigate the onset and severity of the epilepsy associated with the different genetic subtypes of this rare disorder. Furthermore, to use computer-assisted facial gestalt analysis in PIGT-CDG and to the compare findings with other glycosylphosphatidylinositol (GPI) anchor deficiencies. METHODS: We evaluated 13 children from eight unrelated families with homozygous or compound heterozygous pathogenic variants in PIGT. RESULTS: All patients had hypotonia, severe developmental delay, and epilepsy. Epilepsy onset ranged from first day of life to two years of age. Severity of the seizure disorder varied from treatable seizures to severe neonatal onset epileptic encephalopathies. The facial gestalt of patients resembled that of previously published PIGT patients as they were closest to the center of the PIGT cluster in the clinical face phenotype space and were distinguishable from other gene-specific phenotypes. CONCLUSION: We expand our knowledge of PIGT. Our cases reaffirm that the use of genetic testing is essential for diagnosis in this group of disorders. Finally, we show that computer-assisted facial gestalt analysis accurately assigned PIGT cases to the multiple congenital anomalies-hypotonia-seizures syndrome phenotypic series advocating the additional use of next-generation phenotyping technology.

Dominant ELOVL1 mutation causes neurological disorder with ichthyotic keratoderma, spasticity, hypomyelination and dysmorphic features.

BACKGROUND: Ichthyosis and neurological involvement occur in relatively few known Mendelian disorders caused by mutations in genes relevant both for epidermis and neural function. OBJECTIVES: To identify the cause of a similar phenotype of ichthyotic keratoderma, spasticity, mild hypomyelination (on MRI) and dysmorphic features (IKSHD) observed in two unrelated paediatric probands without family history of disease. METHODS: Whole exome sequencing was performed in both patients. The functional effect of prioritised variant in ELOVL1 (very-long-chain fatty acids (VLCFAs) elongase) was analysed by VLCFA profiling by gas chromatography-mass spectrometry in stably transfected HEK2932 cells and in cultured patient's fibroblasts. RESULTS: Probands shared novel heterozygous ELOVL1 p.Ser165Phe mutation (de novo in one family, while in the other family, father could not be tested). In transfected cells p.Ser165Phe: (1) reduced levels of FAs C24:0-C28:0 and C26:1 with the most pronounced effect for C26:0 (P=7.8×10-6 vs HEK293 cells with wild type (wt) construct, no difference vs naïve HEK293) and (2) increased levels of C20:0 and C22:0 (P=6.3×10-7, P=1.2×10-5, for C20:0 and C22:0, respectively, comparison vs HEK293 cells with wt construct; P=2.2×10-7, P=1.9×10-4, respectively, comparison vs naïve HEK293). In skin fibroblasts, there was decrease of C26:1 (P=0.014), C28:0 (P=0.001) and increase of C20:0 (P=0.033) in the patient versus controls. There was a strong correlation (r=0.92, P=0.008) between the FAs profile of patient's fibroblasts and that of p.Ser165Phe transfected HEK293 cells. Serum levels of C20:0-C26:0 FAs were normal, but the C24:0/C22:0 ratio was decreased. CONCLUSION: The ELOVL1 p.Ser165Phe mutation is a likely cause of IKSHD.

Phenotype and genotype of 87 patients with Mowat-Wilson syndrome and recommendations for care.

PURPOSE: Mowat-Wilson syndrome (MWS) is a rare intellectual disability/multiple congenital anomalies syndrome caused by heterozygous mutation of the ZEB2 gene. It is generally underestimated because its rarity and phenotypic variability sometimes make it difficult to recognize. Here, we aimed to better delineate the phenotype, natural history, and genotype-phenotype correlations of MWS. METHODS: In a collaborative study, we analyzed clinical data for 87 patients with molecularly confirmed diagnosis. We described the prevalence of all clinical aspects, including attainment of neurodevelopmental milestones, and compared the data with the various types of underlying ZEB2 pathogenic variations. RESULTS: All anthropometric, somatic, and behavioral features reported here outline a variable but highly consistent phenotype. By presenting the most comprehensive evaluation of MWS to date, we define its clinical evolution occurring with age and derive suggestions for patient management. Furthermore, we observe that its severity correlates with the kind of ZEB2 variation involved, ranging from ZEB2 locus deletions, associated with severe phenotypes, to rare nonmissense intragenic mutations predicted to preserve some ZEB2 protein functionality, accompanying milder clinical presentations. CONCLUSION: Knowledge of the phenotypic spectrum of MWS and its correlation with the genotype will improve its detection rate and the prediction of its features, thus improving patient care.

The mutation responsible for torsion dystonia type 1 shows the ability to stimulate intracellular aggregation of mutant huntingtin.

OBJECTIVE: Introduction: Torsion dystonia type 1 is the most common form of early-onset primary dystonia. Previous reports have suggested that torsin 1A, a protein mutated in this disease, might function as a chaperone that prevents the toxic aggregation of misfolded polypeptides. The aim of the study: The aim of this study was to verify the chaperone function of torsin 1A by investigating its ability to prevent the aggregation of huntingtin model peptides. PATIENTS AND METHODS: Materials and methods: N-terminal mutant huntingtin fragments of different length were co-expressed in neuronal HT-22 and non-neuronal HeLa cells with either the wild-type or mutant (ΔE302/303) torsin 1A protein. The transfected cells were immunostained and analyzed for the presence of huntingtin aggregates using fluorescence microscopy. RESULTS: Results: The immunofluorescence analysis of huntingtin subcellular distribution within the transfected cells showed no significant difference between the huntingtin aggregation levels in cells co-expressing the wild-type torsin 1A and in control cells co-transfected with an empty vector. Instead, it was the increased level of huntingtin aggregation in the presence of the torsion dystonia-causing ΔE302/303 mutant that reached statistical significance in both neuronal and non-neuronal cells. CONCLUSION: Conclusions: Either torsin 1A does not function as a chaperone protein or huntingtin is not an efficient substrate for such a hypothetical chaperone activity. However, the ability of mutant torsin 1A to stimulate the accumulation of aggregation-prone polypeptides might constitute an important source of ΔE302/303 pathogenicity and thus a potential target for future therapy.

[The genetics of obesity - pathogenetic, clinical and diagnostic aspects].

Due to its prevalence and its health-related, economic and social consequences, childhood and adult obesity is a complex, medical and civilizational problem, which has been on the increase in the last decade. The results of multi-center investigations reveal that genetic factors play an essential role in the etiopathogenesis of obesity, particularly in the case of extreme cases with very early onset. The Body Mass Index (BMI) is one of the most frequently used indicators of obesity and shows a strong genetic component with a 40-70% degree of heritability. The three types of genetically conditioned obesity are: (1) isolated (nonsyndromic) monogenic obesity, (2) syndromic monogenic obesity associated with dysmorphic features and/or congenital defects, caused by mutations in specific gene(s), (3) chromosomal aberrations, including submicroscopic changes. The most prevalent common (complex) obesity is linked to the presence of various changes in different genomic loci, which are subject to interactions and modifications by environmental (ethnic, dietary, lifestyle, bacterial flora, oxidative stress), as well as epigenetic (i.e., associated with DNA methylation, histone modification) and epistatic (gene-gene interaction) factors. Recent investigations using the modern methods of genome-wide association studies (GWAS), bioinformatics and proteomics, have made it possible to elucidate 8 key genes among the 97 genes most likely to play significant roles in the metabolic effects of obesity. The results of investigations on the pathogenesis of complex obesity do not as yet clarify the potential pathogenic significance of these genomic changes in humans. This article discusses the neuro-endocrinological regulation of the sensation of hunger and thirst, the clinical consequences of mutations in genes associated with the melanocortin pathway, and the features of the most common obesity syndromes, including syndromes conditioned by genomic imprinting. A diagnostic algorithm for cases of suspected syndromic obesity is proposed.

CAV3 mutation in a patient with transient hyperCKemia and myalgia.

Mutations in caveolin-3 (CAV3) can lead to different clinical phenotypes affecting skeletal or cardiac muscles. Here, we describe a patient with Klinefelter syndrome, ulcerative colitis and Sjögren syndrome, who developed transient hyperCKemia, myalgia and mild muscular weakness. Using whole exome sequencing (WES), a missense mutation G169A was found in the CAV3 gene. In addition, we identified a homozygous frameshift deletion in MS4A12 that may contribute to inflammatory bowel disease, further demonstrating usefulness of WES in dual molecular diagnoses.

Polydactyly and obesity - the clinical manifestation of ciliopathy: a boy with Bardet-Biedl syndrome.

UNLABELLED: The prevalence of obesity in children is still rising all over the world. The most common reason for significant weight gain is a high-calorie diet and decreased physical activity. However, apart from environmental factors, genetic predisposition plays a crucial role in the pathomechanism of obesity. We present the case of a boy with pathological obesity and Bardet-Biedl syndrome (BBS). BBS is a ciliopathy, a heterogeneous group of rare disorders associated with defects in primary cilia. Other clinical signs and symptoms of BBS are: polydactyly, hypertension, hyperlipidemia, hypogonadotrophic hypogonadism, intellectual disability, rod-cone dystrophy, genitourinary and renal abnormalities. CONCLUSIONS: genetic factors of rapid weight gain should be taken into consideration in a child with obesity. Polydactyly can be associated with ciliopathy. A patient with Bardet-Biedl syndrome requires multi-specialist care.

[17p13.3 duplication as a cause of psychomotor developmental delay in an infant - a further case of a new syndrome]. / Duplikacja 17p13.3 jako przyczyna opóznionego rozwoju psychoruchowego u niemowlecia - opis kolejnego przypadku nowego zespolu.

17p13.3 duplication is a rare and heterogeneous genetic syndrome. Microdeletions of this region are responsible for the symptoms of Miller-Dieker syndrome. We present a case of 17p13.3 duplication consisting of about 730kb in a patient with psychomotor developmental delay, concerning eye-hand coordination, posture, locomotion and speech. Among other symptoms, we found excessive physical development in relation to age, hypotonia, dysmorphic facial features (high and prominent forehead, low-set ears, hypertelorism, short nose, small upturned nose, narrow lips and pointed chin) and discrete changes in the CNS - enhanced frontal horns of the lateral ventricles and quite narrow corpus callosum. These symptoms overlap with phenotype of previously described patients with 17p13.3 duplication. The aberration has been identified by array comparative genomic hybridization (aCGH) and confirmed by fluorescence in situ hybridization (FISH). This publication presents a detailed, comparative characteristic of clinical fetures expression in discussed patient with 17p13.3 duplication and patients previously described in medical literature. Further cases with different variants of 17p13.3 duplication may contribute to characterise the specific genotypephenotype correlation.

Variants in CUL4B are associated with cerebral malformations.

Variants in cullin 4B (CUL4B) are a known cause of syndromic X-linked intellectual disability. Here, we describe an additional 25 patients from 11 families with variants in CUL4B. We identified nine different novel variants in these families and confirmed the pathogenicity of all nontruncating variants. Neuroimaging data, available for 15 patients, showed the presence of cerebral malformations in ten patients. The cerebral anomalies comprised malformations of cortical development (MCD), ventriculomegaly, and diminished white matter volume. The phenotypic heterogeneity of the cerebral malformations might result from the involvement of CUL-4B in various cellular pathways essential for normal brain development. Accordingly, we show that CUL-4B interacts with WDR62, a protein in which variants were previously identified in patients with microcephaly and a wide range of MCD. This interaction might contribute to the development of cerebral malformations in patients with variants in CUL4B.

Novel Mutations in the IRF6 Gene on the Background of Known Polymorphisms in Polish Patients With Orofacial Clefting.

OBJECTIVE: To examine the role of the IRF6 mutations in Polish families with Van der Woude syndrome and popliteal pterygium syndrome and to determine the effect of IRF6 single nucleotide polymorphisms (rs7552506, rs2013162, and rs2235375) on cleft lip and/or palate susceptibility. DESIGN: IRF6 mutation screening was performed by direct sequencing of all coding exons of the gene and their flanking intronic regions. Cosegregation analysis was performed to establish the relation of single nucleotide polymorphisms and cleft lip and/or palate phenotypes. PATIENTS: We screened the IRF6 gene in eight families with clinical recognition of Van der Woude syndrome and popliteal pterygium syndrome. RESULTS: In five families we identified pathogenic mutations, all affecting the DNA-binding or the protein-binding domain of IRF6. Two of the mutations were novel-a missense mutation Arg31Thr and a small deletion Trp40Glyfs*23. In most cases we found also a haplotype of three single nucleotide polymorphisms-rs7552506, rs2013162, and rs2235375. The association of the single nucleotide polymorphisms and cleft lip and/or palate susceptibility has been previously published. The variants did not cosegregate with phenotype in examined families nor did they cosegregate with pathogenic mutations. The single nucleotide polymorphisms were deemed not causative, due to their presence in unaffected family members. CONCLUSIONS: Two novel mutations (Arg31Thr and Trp40Glyfs*23) in the IRF6 gene were identified to be causative for Van der Woude and popliteal pterygium syndromes. In the present study no association between the single nucleotide polymorphisms rs7552506, rs2013162, and rs2235375 and the cleft lip and/or palate phenotype was found. The hypothesis, whether the haplotype of the three single nucleotide polymorphisms was correlated with IRF6 expression level, demands further investigation.

Malocclusions and craniofacial anomalies in a child with velo-cardio-facial syndrome.

Velo-Cardio-Facial syndrome (VCFS), also called 22q11.2 microdeletion syndrome, is a rare pathology. The syndrome is caused by 22q11.2 deletion, recognized as one of the most frequent pathogenic human microdeletions. The scope and severity of the phenotypic expression of 22q11.2 microdeletion is characterised by high variability, although cleft palate and congenital conotruncal malformations are among the clinical features often associated with that syndrome. In the presented case of a boy patient with submucous cleft palate and congenital cardiac defect, 22q11.2 microdeletion was identified at the age of 13 months. In the presented paper particular emphasis was placed on the issue of dental and orthodontic care in patients with changes in the oral cavity and the craniofacial area, as well as on the possibilities of treatment and prophylaxis. The necessity to perform a thorough examination of the oral cavity in infants was also underlined as a vital element of clinical assessment, in particular in the case of co-occurring structural defects of internal organs.

Characterization of a 8q21.11 microdeletion syndrome associated with intellectual disability and a recognizable phenotype.

We report eight unrelated individuals with intellectual disability and overlapping submicroscopic deletions of 8q21.11 (0.66-13.55 Mb in size). The deletion was familial in one and simplex in seven individuals. The phenotype was remarkably similar and consisted of a round face with full cheeks, a high forehead, ptosis, cornea opacities, an underdeveloped alae, a short philtrum, a cupid's bow of the upper lip, down-turned corners of the mouth, micrognathia, low-set and prominent ears, and mild finger and toe anomalies (camptodactyly, syndactyly, and broadening of the first rays). Intellectual disability, hypotonia, decreased balance, sensorineural hearing loss, and unusual behavior were frequently observed. A high-resolution oligonucleotide array showed different proximal and distal breakpoints in all of the individuals. Sequencing studies in three of the individuals revealed that proximal and distal breakpoints were located in unique sequences with no apparent homology. The smallest region of overlap was a 539.7 kb interval encompassing three genes: a Zinc Finger Homeobox 4 (ZFHX4), one microRNA of unknown function, and one nonfunctional pseudogen. ZFHX4 encodes a transcription factor expressed in the adult human brain, skeletal muscle, and liver. It has been suggested as a candidate gene for congenital bilateral isolated ptosis. Our results suggest that the 8q21.11 submicroscopic deletion represents a clinically recognizable entity and that a haploinsufficient gene or genes within the minimal deletion region could underlie this syndrome.

The RASopathies as an example of RAS/MAPK pathway disturbances - clinical presentation and molecular pathogenesis of selected syndromes.

The RASopathies are a class of developmental syndromes. Each of them exhibits distinctive phenotypic features, although there are numerous overlapping clinical manifestations that include: dysmorphic craniofacial features, congenital cardiac defects, skin abnormalities, varying degrees of intellectual disability and increased risk of malignancies. These disorders include: Noonan syndrome, Costello syndrome, LEOPARD syndrome, cardio-facio-cutaneous syndrome (CFC), capillary malformation-arteriovenous malformation syndrome (CM-AVM), Legius syndrome and neurofibromatosis type 1 (NF1). The RASopathies are associated with the presence of germline mutation in genes encoding specific proteins of the RAS/mitogen - activated protein kinase (MAPK) pathway that plays a crucial role in embryonic and postnatal development. In this review, we present the clinical and molecular features of selected syndromes from the RASopathies group.