Anwar Baban

Recurrent microdeletion at 17q12 as a cause of Mayer-Rokitansky-Kuster-Hauser (MRKH) syndrome: two case reports

BackgroundMayer-Rokitansky-Kuster-Hauser syndrome (MRKH) consists of congenital aplasia of the uterus and the upper part of vagina due to anomalous development of Müllerian ducts, either isolated or associated with other congenital malformations, including renal, skeletal, hearing and heart defects. This disorder has an incidence of approximately 1 in 4500 newborn girls and the aetiology is poorly understood.Methods and Resultswe report on two patients affected by MRKH syndrome in which array-CGH analysis disclosed an identical deletion spanning 1.5 Mb of genomic DNA at chromosome 17q12. One patient was affected by complete absence of uterus and vagina, with bilaterally normal ovaries, while the other displayed agenesis of the upper part of vagina, right unicornuate uterus, non cavitating rudimentary left horn and bilaterally multicystic kidneys. The deletion encompassed two candidate genes, TCF2 and LHX1. Mutational screening of these genes in a selected group of 20 MRKH females without 17q12 deletion was negative.ConclusionDeletion 17q12 is a rare albeit recurrent anomaly mediated by segmental duplications, previously reported in subjects with developmental kidney abnormalities and diabetes. The present two patients expand the clinical spectrum associated with this imbalance and suggest that this region is a candidate locus for a subset of MRKH syndrome individuals, with or without renal defects.

Coffin-siris syndrome and the BAF complex: Genotype-phenotype study in 63 patients

De novo germline variants in several components of the SWI/SNF‐like BAF complex can cause Coffin–Siris syndrome (CSS), Nicolaides–Baraitser syndrome (NCBRS), and nonsyndromic intellectual disability. We screened 63 patients with a clinical diagnosis of CSS for these genes (ARID1A, ARID1B, SMARCA2, SMARCA4, SMARCB1, and SMARCE1) and identified pathogenic variants in 45 (71%) patients. We found a high proportion of variants in ARID1B (68%). All four pathogenic variants in ARID1A appeared to be mosaic. By using all variants from the Exome Variant Server as test data, we were able to classify variants in ARID1A, ARID1B, and SMARCB1 reliably as being pathogenic or nonpathogenic. For SMARCA2, SMARCA4, and SMARCE1 several variants in the EVS remained unclassified, underlining the importance of parental testing. We have entered all variant and clinical information in LOVD‐powered databases to facilitate further genotype–phenotype correlations, as these will become increasingly important because of the uptake of targeted and untargeted next generation sequencing in diagnostics. The emerging phenotype–genotype correlation is that SMARCB1 patients have the most marked physical phenotype and severe cognitive and growth delay. The variability in phenotype seems most marked in ARID1A and ARID1B patients. Distal limbs anomalies are most marked in ARID1A patients and least in SMARCB1 patients. Numbers are small however, and larger series are needed to confirm this correlation.

Poland syndrome with bilateral features: Case description with review of the literature†

Poland syndrome (PS) has been described as unilateral pectoral muscle deficiency variably associated with ipsilateral thoracic and upper limb anomalies. Bilateral hypoplasia/aplasia of the pectoralis muscle and upper limb defects in association with variable thoracic muscles, chest wall deformities and lower limb defects have been infrequently reported in the literature. We report on a 3½‐year‐old girl with clinical features consisting in bilateral asymmetric pectoral muscle defects (complete agenesis on the left side and agenesis of the sternocostal head on the right side), nipple hypoplasia, left rib defect, and right hand symbrachydactyly. In this study, we reviewed the bilateral features present in our patient and those described in the literature. Hypotheses explaining bilateral features in PS are reviewed.

RASopathies: Clinical Diagnosis in the First Year of Life

Diagnosis within Noonan syndrome and related disorders (RASopathies) still presents a challenge during the first months of life, since most clinical features used to differentiate these conditions become manifest later in childhood. Here, we retrospectively reviewed the clinical records referred to the first year of life of 57 subjects with molecularly confirmed diagnosis of RASopathy, to define the early clinical features characterizing these disorders and improve our knowledge on natural history. Mildly or markedly expressed facial features were invariably present. Congenital heart defects were the clinical issue leading to medical attention in patients with Noonan syndrome and LEOPARD syndrome. Feeding difficulties and developmental motor delay represented the most recurrent features occurring in subjects with cardiofaciocutaneous syndrome and Costello syndrome. Thin hair was prevalent among SHOC2 and BRAF mutation-positive infants. Café-au-lait spots were found in patients with LS and PTPN11 mutations, while keratosis pilaris was more common in individuals with SOS1, SHOC2 and BRAF mutations. In conclusion, some characteristics can be used as hints for suspecting a RASopathy during the first months of life, and individual RASopathies may be suspected by analysis of specific clinical signs. In the first year of life, these include congenital heart defects, severity of feeding difficulties and delay of developmental milestones, hair and skin anomalies, which may help to distinguish different entities, for their subsequent molecular confirmation and appropriate clinical management.

Diagnosis of Noonan syndrome and related disorders using target next generation sequencing

BackgroundNoonan syndrome is an autosomal dominant developmental disorder with a high phenotypic variability, which shares clinical features with other rare conditions, including LEOPARD syndrome, cardiofaciocutaneous syndrome, Noonan-like syndrome with loose anagen hair, and Costello syndrome. This group of related disorders, so-called RASopathies, is caused by germline mutations in distinct genes encoding for components of the RAS-MAPK signalling pathway. Due to high number of genes associated with these disorders, standard diagnostic testing requires expensive and time consuming approaches using Sanger sequencing. In this study we show how targeted Next Generation Sequencing (NGS) technique can enable accurate, faster and cost-effective diagnosis of RASopathies.MethodsIn this study we used a validation set of 10 patients (6 positive controls previously characterized by Sanger-sequencing and 4 negative controls) to assess the analytical sensitivity and specificity of the targeted NGS. As second step, a training set of 80 enrolled patients with a clinical suspect of RASopathies has been tested. Targeted NGS has been successfully applied over 92% of the regions of interest, including exons for the following genes: PTPN11, SOS1, RAF1, BRAF, HRAS, KRAS, NRAS, SHOC, MAP2K1, MAP2K2, CBL.ResultsAll expected variants in patients belonging to the validation set have been identified by targeted NGS providing a detection rate of 100%. Furthermore, all the newly detected mutations in patients from the training set have been confirmed by Sanger sequencing. Absence of any false negative event has been excluded by testing some of the negative patients, randomly selected, with Sanger sequencing.ConclusionHere we show how molecular testing of RASopathies by targeted NGS could allow an early and accurate diagnosis for all enrolled patients, enabling a prompt diagnosis especially for those patients with mild, non-specific or atypical features, in whom the detection of the causative mutation usually requires prolonged diagnostic timings when using standard routine. This approach strongly improved genetic counselling and clinical management.

Dextrocardia in patients with Poland syndrome: Phenotypic characterization provides insight into the pathogenesis

OBJECTIVE Poland syndrome is a rare congenital anomaly characterized by complete or partial agenesis of the pectoralis major muscle variably associated with other thoracic malformations, upper limb malformations, or both. More than 20 patients with dextrocardia and left-sided Poland syndrome have been previously described. The association between these 2 rare anomalies suggests a causal relationship, but the etiopathogenetic mechanism has not been clarified yet. We studied the clinical correlation between these 2 anomalies, and we tried to elucidate whether dextrocardia or Poland syndrome comes first. METHODS This is a multicentric multidisciplinary study conducted over the last 5 years. We identified 122 patients with Poland syndrome, and we investigated heart position through different imaging techniques. Logistic regression statistical analyses were carried out. RESULTS We observed dextrocardia in 14 (11.5%) patients, which was never associated with situs inversus. All of them presented with left-sided Poland syndrome and partial agenesis of 2 or more ribs. Conversely, all patients with Poland syndrome with partial agenesis of 2 or more ribs presented with dextrocardia, whereas dextrocardia was never associated with partial agenesis of a single rib. Three patients with dextrocardia presented with simple congenital heart defects. CONCLUSIONS These findings suggest that mechanical factors during embryonic life could explain the strong association between left-sided Poland syndrome and dextrocardia. According to this hypothesis, partial agenesis of 2 or more ribs is needed to displace the heart toward the right side. The peculiar features of dextrocardia when associated with Poland syndrome (neither associated with situs inversus nor complex intracardiac anomalies) support our hypothesis.

Ebstein anomaly: Genetic heterogeneity and association with microdeletions 1p36 and 8p23.1.

Ebstein anomaly is an uncommon congenital heart defect (CHD), characterized by downward displacement of the tricuspid valve into the right ventricle. To uncover the genetic associations with Ebstein anomaly, we have searched chromosomal imbalances using standard cytogenetic and array‐CGH analysis, and single gene conditions associated with syndromic Ebstein anomaly (with extracardiac anomalies), and screened GATA4 and NKX2.5 mutations in nonsyndromic patients (without extracardiac anomalies). Between January 1997 and September 2009, 44 consecutive patients with Ebstein anomaly were evaluated in two centers of Pediatric Cardiology. Ebstein anomaly was syndromic in 12 (27%) patients, and nonsyndromic in 32 (73%). A recognizable syndrome or complex was diagnosed by clinical criteria in seven patients. In one syndromic patient an 18q deletion was diagnosed by standard cytogenetic analysis. Array‐CGH analysis performed in 10 of the 12 syndromic patients detected an interstitial deletion of about 4 Mb at 8p23.1 in one patient, and a deletion 1pter > 1p36.32/dup Xpter‐ > Xp22.32 in another patient. In the 28 of 32 nonsyndromic patients who underwent molecular testing, no mutation in GATA4 and NKX2.5 genes were detected. We conclude that Ebstein anomaly is a genetically heterogeneous defect, and that deletion 1p36 and deletion 8p23.1 are the most frequent chromosomal imbalances associated with Ebstein anomaly. Candidate genes include the GATA4 gene (in patients with del 8p23.1), NKX2.5 (based on published patients with isolated Ebstein anomaly) and a hypothetical gene in patients with del 1p36).

Identification of TBX5 mutations in a series of 94 patients with Tetralogy of Fallot

Tetralogy of Fallot (TOF) (OMIM #187500) is the most frequent conotruncal congenital heart defect (CHD) with a range of intra‐ and extracardiac phenotypes. TBX5 is a transcription factor with well‐defined roles in heart and forelimb development, and mutations in TBX5 are associated with Holt–Oram syndrome (HOS) (OMIM#142900). Here we report on the screening of 94 TOF patients for mutations in TBX5, NKX2.5 and GATA4 genes. We identified two heterozygous mutations in TBX5. One mutation was detected in a Moroccan patient with TOF, a large ostium secundum atrial septal defect and complete atrioventricular block, and features of HOS including bilateral triphalangeal thumbs and fifth finger clinodactyly. This patient carried a previously described de novo, stop codon mutation (p.R279X) located in exon 8 causing a premature truncated protein. In a second patient from Italy with TOF, ostium secundum atrial septal defect and progressive arrhythmic changes on ECG, we identified a maternally inherited novel mutation in exon 9, which caused a substitution of a serine with a leucine at amino acid position 372 (p.S372L, c.1115C>T). The mothers clinical evaluation demonstrated frequent ventricular extrasystoles and an atrial septal aneurysm. Physical examination and radiographs of the hands showed no apparent skeletal defects in either child or mother. Molecular evaluation of the p.S372L mutation demonstrated a gain‐of‐function phenotype. We also review the literature on the co‐occurrence of TOF and HOS, highlighting its relevance. This is the first systematic screening for TBX5 mutations in TOF patients which detected mutations in two of 94 (2.1%) patients.

Syndromic non-compaction of the left ventricle: Associated chromosomal anomalies

Non‐compaction of the left ventricle (NCLV) is a cardiomyopathy characterized by prominent left ventricular trabeculae and deep intertrabecular recesses. Associated extracardiac anomalies occur in 14–66% of patients of different series, while chromosomal anomalies were reported in sporadic cases. We investigated the prevalence of chromosomal imbalances in 25 syndromic patients with NCLV, using standard cytogenetic, subtelomeric fluorescent in situ hybridization, and array‐comparative genomic hybridization (CGH) analyses. Standard chromosome analysis disclosed an abnormality in three (12%) patients, including a 45,X/46,XX mosaic, a 45,X/46,X,i(Y)(p11) mosaic, and a de novo Robertsonian 13;14 translocation in a child affected by hypomelanosis of Ito. Cryptic chromosome anomalies were found in six (24%) cases, including 1p36 deletion in two patients, 7p14.3p14.1 deletion, 18p subtelomeric deletion, 22q11.2 deletion associated with velo‐cardio‐facial syndrome, and distal 22q11.2 deletion, each in one case. These results recommend accurate clinical evaluation of patients with NCLV, and suggest that chromosome anomalies occur in about one third of syndromic NCLV individuals, without metabolic/neuromuscular disorder. Array‐CGH analysis should be included in the diagnostic protocol of these patients, because different submicroscopic imbalances are causally associated with this disorder and can pinpoint candidate genes for this cardiomyopathy.

Exome sequencing identifies a novel mutation in PIK3R1 as the cause of SHORT syndrome

BackgroundSHORT syndrome is a rare autosomal dominant condition whose name is the acronym of short stature, hyperextensibility of joints, ocular depression, Rieger anomaly and teething delay (MIM 269880). Additionally, the patients usually present a low birth weight and height, lipodystrophy, delayed bone age, hernias, low body mass index and a progeroid appearance.Case presentationIn this study, we used whole-exome sequencing approaches in two patients with clinical features of SHORT syndrome. We report the finding of a novel mutation in PIK3R1 (c.1929_1933delTGGCA; p.Asp643Aspfs*8), as well as a recurrent mutation c.1945C > T (p.Arg649Trp) in this gene.ConclusionsWe found a novel frameshift mutation in PIK3R1 (c.1929_1933delTGGCA; p.Asp643Aspfs*8) which consists of a deletion right before the site of substrate recognition. As a consequence, the protein lacks the position that interacts with the phosphotyrosine residue of the substrate, resulting in the development of SHORT syndrome.