Congenital heart defects in the recurrent 2q13 deletion syndrome.

The recurrent 2q13 deletion syndrome is a rare genetic disorder associated with developmental delay, cardiac and urogenital malformations, and minor facial anomalies. Congenital heart defects (CHDs) are the most frequent malformations associated with del2q13. Experimental studies in zebrafish suggest that two genes mapping within the 2q13 critical region (FBLN7 and TMEM87B) could confer susceptibility to congenital heart defects in affected individuals. We reviewed the cardiac characteristics in four patients with 2q13 deletion admitted to our hospitals, and in published patients. Two of our patients had congenital heart defects, consisting in partial anomalous pulmonary venous connection, ostium secundum atrial septal defect ostium secundum, and small muscular ventricular septal defect in one of them, and aortic valve insufficiency with partial fusion of two commissures (incomplete bicuspid aortic valve) and mitral valve insufficiency due to trivial mitral valve prolapse in the other. The anatomic types of CHD in del2q13 syndrome are highly variable and distributed widely, including laterality defects, complex atrioventricular septal defect, septal anomalies, and cardiomyopathies. Cardiac evaluation should be part of the clinical workup at diagnosis of 2q13 deletion.

Atrioventricular canal defect and genetic syndromes: The unifying role of sonic hedgehog.

The atrioventricular canal defect (AVCD) is a congenital heart defect (CHD) frequently associated with extracardiac anomalies (75%). Previous observations from a personal series of patients with AVCD and "polydactyly syndromes" showed that the distinct morphology and combination of AVCD features in some of these syndromes is reminiscent of the cardiac phenotype found in heterotaxy, a malformation complex previously associated with functional cilia abnormalities and aberrant Hedgehog (Hh) signaling. Hh signaling coordinates multiple aspects of left-right lateralization and cardiovascular growth. Being active at the venous pole the secondary heart field (SHF) is essential for normal development of dorsal mesenchymal protrusion and AVCD formation and septation. Experimental data show that perturbations of different components of the Hh pathway can lead to developmental errors presenting with partially overlapping manifestations and AVCD as a common denominator. We review the potential role of Hh signaling in the pathogenesis of AVCD in different genetic disorders. AVCD can be viewed as part of a "developmental field," according to the concept that malformations can be due to defects in signal transduction cascades or pathways, as morphogenetic units which may be altered by Mendelian mutations, aneuploidies, and environmental causes.

Intrafamiliar clinical variability of circumferential skin creases Kunze type caused by a novel heterozygous mutation of N-terminal TUBB gene.

Circumferential skin creases Kunze type (CSC-KT; OMIM 156610, 616734) is a rare disorder characterized by folding of excess skin, which leads to ringed creases, known as Michelin Tire Baby Syndrome (MTBS). CSC-KT patients also exhibit facial dysmorphism, growth retardation, intellectual disability (ID) and multiple congenital malformations. Recently, 2 heterozygous mutations in TUBB gene and 4 mutations (both homozygous and heterozygous) in MAPRE2 gene were identified in 3 and 4 CSC-KT patients, respectively. In the 3 TUBB gene-related CSC-KT patients, all mutations fall in the N-terminal gene domain and were de novo. Mutations in the C-terminal of TUBB gene have been associated to microcephaly and structural brain malformation, in the absence of CSC-KT features. We report a 9-year-old boy with a diagnosis of CSC-KT based on MTBS, facial dysmorphism, microcephaly, severe ID, cortical atrophy and corpus callosum hypoplasia. Sanger sequencing identified a novel heterozygous c.218T>C (p.Met73Thr) mutation in the N-terminal of TUBB gene, that was inherited from the mother affected by isolated MTBS. This is the first report of inherited TUBB gene-related CSC-KT resulting from a novel heterozygous mutation in the N-terminal domain. Present data support the role of TUBB mutations in CSC-KT and definitely includes CSC-KT syndrome within the tubulinopathies.

Biallelic mutations in DYNC2LI1 are a rare cause of Ellis-van Creveld syndrome.

Ellis-van Creveld syndrome (EvC) is a chondral and ectodermal dysplasia caused by biallelic mutations in the EVC, EVC2 and WDR35 genes. A proportion of cases with clinical diagnosis of EvC, however, do not carry mutations in these genes. To identify the genetic cause of EvC in a cohort of mutation-negative patients, exome sequencing was undertaken in a family with 3 affected members, and mutation scanning of a panel of clinically and functionally relevant genes was performed in 24 additional subjects with features fitting/overlapping EvC. Compound heterozygosity for the c.2T>C (p.Met1?) and c.662C>T (p.Thr221Ile) variants in DYNC2LI1, which encodes a component of the intraflagellar transport-related dynein-2 complex previously found mutated in other short-rib thoracic dysplasias, was identified in the 3 affected members of the first family. Targeted resequencing detected compound heterozygosity for the same missense variant and a truncating change (p.Val141*) in 2 siblings with EvC from a second family, while a newborn with a more severe phenotype carried 2 DYNC2LI1 truncating variants. Our findings indicate that DYNC2LI1 mutations are associated with a wider clinical spectrum than previously appreciated, including EvC, with the severity of the phenotype likely depending on the extent of defective DYNC2LI1 function.

Expanding the clinical and molecular spectrum of PRMT7 mutations: 3 additional patients and review.

Protein arginine methyltransferase 7 (PRMT7) is a member of a family of enzymes that catalyze the transfer of methyl groups from S-adenosyl-l-methionine to nitrogen atoms on arginine residues. Arginine methylation is involved in multiple biological processes, such as signal transduction, mRNA splicing, transcriptional control, DNA repair, and protein translocation. Currently, 7 patients have been described harboring compound heterozygous or homozygous variants in the PRMT7 gene, causing a novel intellectual disability syndrome, known as SBIDDS syndrome (Short Stature, Brachydactyly, Intellectual Developmental Disability, and Seizures). We report on 3 additional patients from 2 consanguineous families with severe/moderate intellectual disability, short stature, brachydactyly and dysmorphisms. Exome sequencing revealed 2 novel homozygous mutations in PRMT7. Our findings expand the clinical and molecular spectrum of homozygous PRMT7 mutations, associated to the SBIDDS syndrome, showing a possible correlation between the type of mutation and the severity of the phenotype.

Evaluation of Clinical Manifestations in Patients with Severe Lymphedema with and without CCBE1 Mutations.

The lymphedema-lymphangiectasia-intellectual disability (Hennekam) syndrome (HS) is characterised by a widespread congenital lymph vessel dysplasia manifesting as congenital lymphedema of the limbs and intestinal lymphangiectasia, accompanied by unusual facial morphology, variable intellectual disabilities and infrequently malformations. The syndrome is heterogeneous as mutations in the gene CCBE1 have been found responsible for the syndrome in only a subset of patients. We investigated whether it would be possible to predict the presence of a CCBE1 mutation based on phenotype by collecting clinical data of patients diagnosed with HS, with or without a CCBE1 mutation. We report here the results of 13 CCBE1 positive patients, 16 CCBE1 negative patients, who were clinically found to have classical HS, and 8 patients in whom the diagnosis was considered possible, but not certain, and in whom no CCBE1 mutation was identified. We found no statistically significant phenotypic differences between the 2 groups with the clinical HS phenotype, although the degree of lymphatic dysplasia tended to be more pronounced in the mutation positive group. We also screened 158 patients with less widespread and less pronounced forms of lymphatic dysplasia for CCBE1 mutations, and no mutation was detected in this group. Our results suggest that (1) CCBE1 mutations are present only in patients with a likely clinical diagnosis of HS, and not in patients with less marked forms of lymphatic dysplasia, and (2) that there are no major phenotypic differences between HS patients with or without CCBE1 mutations.

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.

Genetic prediction of common diseases. Still no help for the clinical diabetologist!

Genome-wide association studies (GWAS) have identified several loci associated with many common, multifactorial diseases which have been recently used to market genetic testing directly to the consumers. We here addressed the clinical utility of such GWAS-derived genetic information in predicting type 2 diabetes mellitus (T2DM) and coronary artery disease (CAD) in diabetic patients. In addition, the development of new statistical approaches, novel technologies of genome sequencing and ethical, legal and social aspects related to genetic testing have been also addressed. Available data clearly show that, similarly to what reported for most common diseases, genetic testing offered today by commercial companies cannot be used as predicting tools for T2DM and CAD. Further studies taking into account the complex interaction between genes as well as between genetic and non-genetic factors, including age, obesity and glycemic control which seem to modify genetic effects on the risk of T2DM and CAD, might mitigate such negative conclusions. Also, addressing the role of relatively rare variants by next generation sequencing may help identify novel and strong genetic markers with an important role in genetic prediction. Finally, statistical tools concentrated on reclassifying patients might be a useful application of genetic information for predicting many common diseases. By now, prediction of such diseases, including those of interest for the clinical diabetologist, have to be pursued by using traditional clinical markers which perform well and are not costly.

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.

New mutations in ZFPM2/FOG2 gene in tetralogy of Fallot and double outlet right ventricle.

Conotruncal defects (CTDs) represent 15-20% of all congenital heart defects. Mutations in a number of genes have been associated with CTD in humans and animal models. We investigated the occurrence and the prevalence of GATA4, NKX2.5, ZFPM2/FOG2, GDF1, and ISLET1 gene mutations in a large cohort of individuals with CTD, including tetralogy of Fallot with or without pulmonary atresia (TOF, 178 patients), double outlet right ventricle (DORV, 13 patients), and truncus arteriosus (11 patients). Denaturing high-performance liquid chromatography (DHPLC) analysis followed by bidirectional sequencing disclosed no putative pathogenic mutation in GATA4, ISLET1, and GDF1 genes. Two novel (Ile227Val, Met544Ile) and one previously reported (Glu30Gly) possibly pathogenic missense variants were identified in the ZFPM2/FOG2 gene in 3 sporadic patients of 202 (1.5%) with CTD, including 1 of 178 (0.6%) with TOF and 2 of 13 (15.4%) with DORV. Mutation analysis also detected one known missense change (Arg25Cys) in NKX2.5 gene in two (1.1%) sporadic patients with TOF. These sequence alterations were found to be absent in 500 population-matched controls. In conclusion, the present results (i) indicate and confirm that mutations in the GATA4, GDF1, and ISLET1 genes are not major determinants in the pathogenesis of TOF, (ii) provide supportive evidence of an association between ZFPM2/FOG2 gene and TOF/DORV, and (iii) provide additional examples of the possible contribution of the Arg25Cys change in the NKX2.5 to a small number of TOF cases.

TRIB3 R84 variant affects glucose homeostasis by altering the interplay between insulin sensitivity and secretion.

AIMS/HYPOTHESIS: The results of studies on the genetics of complex traits need to be replicated and to reach robust statistical significance before they can be considered as established. We here tried to replicate the previously reported association between the TRIB3 Q84R polymorphism (rs2295490) and glucose homeostasis. METHODS: Three samples of Europeans with fasting glucose <7.0 mmol/l were studied. In sample 1 (n=791), the association between TRIB3 Q84R and impaired glucose regulation (IGR; defined as impaired fasting glucose and/or impaired glucose tolerance and/or type 2 diabetes by OGTT) and insulin sensitivity (ISI), and its interplay with early-phase insulin secretion (i.e. disposition index [DI]) were analysed. Sample 2 (n=374) and sample 3 (n=394) were used to replicate the association with IGR and insulin sensitivity (by glucose clamp), respectively. Genotyping was performed by TaqMan allele discrimination. RESULTS: R84 carriers were at higher risk of IGR: OR for the additive model 1.54, p=0.004, and 1.63, p=0.027, in samples 1 and 2, respectively. In sample 1, both ISI (p=0.005) and DI (p=0.043) were progressively lower from QQ to QR and RR individuals. A 'triangulation approach' indicated that the association with IGR was mostly mediated by DI rather than by ISI changes (i.e. being the expected ORs 1.51 and 1.25, respectively). In sample 3, glucose disposal was 38.8+/-17.7, 33.8+/-14.4, and 31.6+/-13.3 micromol min(-1)kg(-1), p=0.022, in QQ, QR and RR individuals, respectively. CONCLUSIONS/INTERPRETATION: Our data confirm that the TRIB3 R84 variant affects glucose homeostasis and suggest this effect is due to an alteration of the interplay between insulin sensitivity and secretion.

A novel homozygous splice site mutation in the HPGD gene causes mild primary hypertrophic osteoarthropathy.

OBJECTIVES: Homozygous mutations in HPGD gene, encoding 15-hydroxyprostaglandin dehydrogenase, have recently been associated with primary hypertrophic osteoarthropathy (PHO). So far, only 7 HPGD alterations are known. In order to expand this mutational spectrum and better delineate the HPGD-related phenotype, we report the clinical and molecular characterisation of a 13-year-old boy and compare his features to known mutated patients. METHODS: The HPGD gene exons 1-7 and exon-intron junctions were analysed by direct sequencing. Previously published HPGD-mutated patients were systematically reviewed based on the original clinical description. RESULTS: A novel homozygous c.217+1G>A mutation affecting the obligatory donor splice site of HPGD exon 2 was identified in our proband who showed a mild form of PHO. Review of HPGD-mutated patients outlined all patients manifested digital clubbing, periostosis and acro-osteolysis. Hyperhidrosis (92%), arthralgia (65%) and eczema (33%) were variably associated features. Pachydermia (54%) was mild and mostly limited to palms and sole; cutis vertigis gyrata, blepharoptosis and severe skin thickening were never observed. Besides digital clubbing, PHO infants often presented patent ductus arteriosus (PDA) (32%) and delayed cranial sutures closure (55%). CONCLUSIONS: The present findings broaden the allelic spectrum of HPGD gene to include a novel c.217+1G>A mutation. Mutated patients display a homogeneous phenotype mainly consisting in digital clubbing, periostosis, acro-osteolysis, hyperhidrosis and mild pachydermia. Earliest manifestations include delayed closure of the cranial sutures and PDA. In conclusion, the information reported herein would facilitate the diagnosis of PHO due to HPGD mutations.

The Parkinson-associated protein PINK1 interacts with Beclin1 and promotes autophagy.

Mutations in the PINK1 gene cause autosomal recessive Parkinson's disease. The PINK1 gene encodes a protein kinase that is mitochondrially cleaved to generate two mature isoforms. In addition to its protective role against mitochondrial dysfunction and apoptosis, PINK1 is also known to regulate mitochondrial dynamics acting upstream of the PD-related protein Parkin. Recent data showed that mitochondrial Parkin promotes the autophagic degradation of dysfunctional mitochondria, and that stable PINK1 silencing may have an indirect role in mitophagy activation. Here we report a new interaction between PINK1 and Beclin1, a key pro-autophagic protein already implicated in the pathogenesis of Alzheimer's and Huntington's diseases. Both PINK1 N- and C-terminal are required for the interaction, suggesting that full-length PINK1, and not its cleaved isoforms, interacts with Beclin1. We also demonstrate that PINK1 significantly enhances basal and starvation-induced autophagy, which is reduced by knocking down Beclin1 expression or by inhibiting the Beclin1 partner Vps34. A mutant, PINK1(W437X), interaction of which with Beclin1 is largely impaired, lacks the ability to enhance autophagy, whereas this is not observed for PINK1(G309D), a mutant with defective kinase activity but unaltered ability to bind Beclin1. These findings identify a new function of PINK1 and further strengthen the link between autophagy and proteins implicated in the neurodegenerative process.

Effect of a CYP2D6 polymorphism on the efficacy of donepezil in patients with Alzheimer disease.

OBJECTIVE: To evaluate the influence of the single nucleotide polymorphism rs1080985 in the cytochrome P450 2D6 (CYP2D6) gene on the efficacy of donepezil in patients with mild to moderate Alzheimer disease (AD). METHODS: This was a multicenter, prospective cohort study of 127 white patients with AD according to the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association Work Group criteria. Patients were treated with donepezil 5-10 mg/daily for 6 months. Cognitive and functional statuses were evaluated at baseline and at 6-month follow-up. Response to therapy was defined according to the National Institute for Health and Clinical Excellence criteria. Compliance and drug-related adverse events were also evaluated. The analyses identifying the CYP2D6 and APOE polymorphisms were performed in blinded fashion. RESULTS: At 6-month follow-up, 69 of 115 patients (60%) were responders and 46 patients (40%) were nonresponders to donepezil treatment. A significantly higher frequency of patients with the G allele of rs1080985 was found in nonresponders than in responders (58.7% vs 34.8%, p = 0.013). Logistic regression analysis adjusted for age, sex, Mini-Mental State Examination score at baseline, and APOE demonstrated that patients with the G allele had a significantly higher risk of poor response to donepezil treatment (odds ratio 3.431, 95% confidence interval 1.490-7.901). CONCLUSIONS: The single nucleotide polymorphism rs1080985 in the CYP2D6 gene may influence the clinical efficacy of donepezil in patients with mild to moderate Alzheimer disease (AD). The analysis of CYP2D6 genotypes may be useful in identifying subgroups of patients with AD who have different clinical responses to donepezil.

IRS1 G972R polymorphism and type 2 diabetes: a paradigm for the difficult ascertainment of the contribution to disease susceptibility of 'low-frequency-low-risk' variants.

AIMS/HYPOTHESIS: The aim of the study was to determine the association between IRS1 G972R polymorphism and type 2 diabetes; published data concerning this association have been conflicting. To obtain further insight into this topic, we performed a meta-analysis of all available case-control studies. METHODS: We performed a meta-analysis of 32 studies (12,076 cases and 11,285 controls). RESULTS: The relatively infrequent R972 variant was not significantly associated with type 2 diabetes (OR 1.09, 95% CI 0.96-1.23, p = 0.184 under a dominant model). Some evidence of heterogeneity was observed across studies (p = 0.1). In the 14 studies (9,713 individuals) in which the mean age at type 2 diabetes diagnosis was available, this variable explained 52% of the heterogeneity (p = 0.03). When these studies were subdivided into tertiles of mean age at diagnosis, the OR for diabetes was 1.48 (95% CI 1.17-1.87), 1.22 (95% CI 0.97-1.53) and 0.88 (95% CI 0.68-1.13) in the youngest, intermediate and oldest tertile, respectively (p = 0.0022 for trend of ORs). CONCLUSIONS/INTERPRETATION: Our findings illustrate the difficulties of ascertaining the contribution of 'low-frequency-low-risk' variants to type 2 diabetes susceptibility. In the specific context of the R972 variant, approximately 200,000 study individuals would be needed to have 80% power to identify a 9% increase in diabetes risk at a genome-wide significance level. Under these circumstances, a strategy aimed at improving outcome definition and decreasing its heterogeneity may critically enhance our ability to detect genetic effects, thereby decreasing the required sample size. Our data suggest that focusing on early-onset diabetes, which is characterised by a stronger genetic background, may be part of such a strategy.

Joubert syndrome with bilateral polymicrogyria: clinical and neuropathological findings in two brothers.

Joubert syndrome (JS) is characterized by hypotonia, ataxia, developmental delay, and a typical neuroimaging finding, the so-called "molar tooth sign" (MTS). The association of MTS and polymicrogyria (PMG) has been reported as a distinct JS-related disorder (JSRD). So far, five patients have been reported with this phenotype, only two of them being siblings. We report on one additional family, describing a living child with JS and PMG, and the corresponding neuropathological picture in the aborted brother. No mutations were detected in the AHI1 gene, the only so far associated with the JS + PMG phenotype. Moreover, linkage analysis allowed excluding all known gene loci, suggesting further genetic heterogeneity.