Alagille syndrome: Experience of a tertiary care center in North India

Alagille syndrome (AGS) is an autosomal dominant disorder of chronic cholestasis characterized by paucity of interlobular bile ducts. The condition has been described only as isolated case reports in India. We describe clinical profile and outcome of nine subjects (six infants and three older children) with AGS. Cholestasis and characteristic facies were present in all, followed by congenital heart disease, vertebral anomalies, and posterior embryotoxon in seven, five, and four cases, respectively. Pruritus was the commonest symptom which was refractory to medical treatment in one third of cases. Two cases developed decompensated liver disease on follow up. High index of suspicion for this multisystemic condition is essential for correct diagnosis and management.     

PRKAG2基因R302Q突变致同胞兄弟不同临床表现的研究

目的本研究报道了均携带R302Q突变却具有完全不同临床表现的同胞兄弟二人病例,分析R302Q突变引起PRKAG2心脏综合征的异质性。方法收集临床资料并进行基因测序检测其突变,结合其他家系和实验研究结果进行分析。结果心脏超声示先证者心肌肥厚,其胞弟心超未见明显异常。先证者心电图呈现比较典型的PRKAG2心脏综合征心电图改变如Ⅱ度房室传导阻滞,而胞弟则有偶尔腿部肌肉酸痛和肌型肌酸激酶同功酶(CK-MM)升高表现。结论本研究中兄弟二人截然不同的临床表现显示,即使在同一家系中,R302Q突变引起PRKAG2心脏综合征也具有显著的异质性。     

Increasing the mutation rate for Jagged1 mutations in patients with Alagille syndrome

Alagille syndrome (AGS) is caused by heterozygous mutations in JAG1, and mutations have been previously reported in about 70% of patients who meet clinical diagnostic criteria. We studied a cohort of 247 clinically well-defined patients, and using an aggressive and sequential screening approach we identified JAG1 mutations in 94% of individuals. Mutations were found in 232 out of 247 patients studied and 83 of the mutations were novel. This increase in the mutation rate was accomplished by combining rigorous clinical phenotyping, with a combination of mutation detection techniques, including fluorescence in situ hybridization (FISH), genomic and cDNA sequencing, and quantitative PCR. This higher rate of mutation identification has implications for clinical practice, facilitating genetic counseling, prenatal diagnosis, and evaluation of living-related liver transplant donors. Our results suggest that more aggressive screening may similarly increase the rate of mutation detection in other dominant and recessive disorders.     

Alagille syndrome. The widening spectrum of arteriohepatic dysplasia

Alagille syndrome was described more than 35 years ago as a genetic entity characterized by five major features: chronic cholestasis resulting from paucity of interlobular bile ducts, peripheral pulmonary stenosis, butterflylike vertebral arch defect, posterior embryotoxon, and peculiar facies. Recently, JAGGED1 has been identified as a responsible gene by demonstration of mutations in AGS patients. Studies of the JAGGED1 expression pattern demonstrate that minor features and almost all the elements in the long list of manifestations described in AGS patients are not coincidental. This finding suggests that the definition of AGS may be reconsidered in the light of JAGGED1 mutations.     

Diagnostic challenges of Marfan syndrome in an XYY young man

Tall stature is a common feature of both Marfan syndrome and XYY syndrome. Differential diagnosis between these entities has important prognostic implications. We report the case of a 21-year-old young man with a previously known diagnosis of XYY syndrome, in whom the identification of a fibrilin-1 mutation was determinant to establish an appropriate diagnosis, medical follow-up, and genetic counselling.     

心脏核磁共振成像技术在肥厚型心肌病中的应用现状及最新进展

Hypertrophic cardiomyopathy(HCM)is the most common genetic cardiomyopathy and the leading cause of sudden death in young people and a major cause of heart failure symptoms at any age.Due to its genetic etiology,there is substantial heterogeneity in the phenotypic expression and clinical course of patients with HCM.Traditionally,two-dimensional echocardiography has been the easiest and reliable technique for establishing a diagnosis of HCM.However,cardiovascular magnetic resonance(CMR)has emerged as a novel,3-dimensional tomographic imaging technique,which provides high spatial and temporal resolution images of the heart (not limited by thoracic or pulmonary parenchyma),in any plane and without ionizing radiation.As a result,CMR is particularly well suited to provide detailed characterization of the HCM phenotype,including a precise assessment of the location and distribution of LV wall thickening(as well as other myocardial structures such as the right ventricle and papillary muscles).In this regard,CMR has been demonstrated to provide a diagnosis of HCM in cases where the echocardiogam was non-diagnostic.Furthermore,CMR provides an accurate assessment of total LV mass which is a more robust marker of hypertrophy,with potential implications for risk stratification.In addition,with the intravenous administration of gadolinium,first-pass perfusion sequences can identify myocardial perfusion abnormalities,while late gadolinium enhancement sequences can identify areas of myocardial fibrosis/scarring.Although the clinical implications of late gadolinium enhancement in HCM are still uncertain this information may,in the near-future,have important implications with regard to identifying HCM patients at high risk of sudden death and progressive heart failure,including evolution into the end-stage phase of HCM.Therefore,at present,CMR provides important information impacting on diagnosis and clinical management strategies in patients with HCM and will likely have an expanding role in the evaluation of patients with this complex disease.     

Genetic background of congenital conotruncal heart defects--a study of 45 families

INTRODUCTION: The latest achievements in molecular diagnosis create new possibilities for evaluation of congenital abnormalities. AIM: To present our preliminary experience with genetic diagnosis of congenital combined conotruncal heart defects. METHODS: The analysis comprised 35 families with more than one member suffering from conotruncal heart defects (Group I) and 10 families (Group II) having a child with the clinical features of CATCH 22 syndrome. All family pedigrees were performed. Each patient was investigated by echocardiography to assess the diagnosis of the cardiac defect. Anamnestic information with regard to developmental milestones, learning abilities in childhood and psychiatric disorders were recorded. All individuals were qualified for further genetic molecular diagnostic procedures such as FISH analysis for microdeletion of chromosome 22q11 using probe N25 DiGeorge Region with 22qter control Direct CP 5141-DC. RESULTS: Based on the pedigree analysis in Group I we suggest that complex heart defects are transmitted as a recessive variant. None of the members of these families has the clinical features of CATCH 22 syndrome. In Group II we did not find familial predisposition for the appearance of congenital heart defects. None of the evaluated members of the families from Group I had microdeletion of chromosome 22q11 based on FISH analysis so we decided to isolate DNA for further molecular diagnosis. In group II in 6 (60%) individuals with typical features for CATCH 22 syndrome FISH analysis confirmed microdeletion of chromosome 22q11. CONCLUSIONS: 1. The huge progress in molecular genetics creates new possibilities in the diagnosis of congenital heart defects. 2. The identification of families with high risk of recurrence of conotruncal heart defects enables genetic counselling and highly specialised medical care at the proper time.     

Fetal echocardiography and clinical genetics--a close correlation

Improving techniques in fetal echocardiography have important implications in the field of clinical genetics. 1) Fetal echocardiography in pregnancies with families with increased recurrence risks for congenital heart disease (CHD): In 473 pregnancies with increased recurrence risks for CHD second-trimester fetal echocardiography was performed. In 11 cases (2.3%) cardiac malformations were present that could be diagnosed in five cases prenatally (hypoplastic left heart, complete atrioventricular canal defect with hypoplastic left ventricle, preductal coarctation of aorta, tetralogy of Fallot, complete atrioventricular canal defect). In six cases the prenatal diagnosis could not be performed (total anomalous pulmonary venous connection [one case], secundum atrial septal defect [two cases], ventricular septal defect [three cases]). The recurrence risk in families with one previously affected child was 1.4% (5/364), and 17.6% (3/17) in families with two previously affected children. In two out of 44 cases with one affected parent a CHD could be diagnosed, in both cases one previous child was already affected. 2) Congenital heart defect as a common symptom in malformation syndromes: CHD is common as a symptom in malformation syndromes. The demonstration of a fetal CHD can lead to diagnosis of a complex malformation syndrome and it is integral in prenatal diagnosis in cases with increased recurrence risks for a complex malformation syndrome. The sonographic diagnosis of a CHD may signal associated chromosomal disorders. Between January 1986 and December 1988 in 433 cases with prenatally diagnosed congenital malformation and/or severe fetal growth retardation a prenatal chromosome analysis was performed. Within this group 77 fetuses demonstrated a CHD and 28 (36%) out of these revealed a chromosomal disorder. The genetic basis of CHD, the most common complex syndromes with CHD, and the principles of genetic counseling in families with CHD are summarized.     

Unruptured Sinus of Valsalva Aneurysm in a Neonate with Hypoplastic Left Heart Syndrome: Echocardiographic Diagnosis and Features

An unruptured sinus of Valsalva aneurysm is usually asymptomatic, and a rare, often incidental echocardiographic diagnosis. Its presentation in the neonatal period is extremely rare. We describe this finding in a neonate with hypoplastic left heart syndrome, which has not been previously reported in the literature. This constellation of findings may have important clinical implications in regards to medical management and surgical options.     

Activator of G protein signaling 3 is a guanine dissociation inhibitor for Galpha i subunits

Activator of G protein signaling 3 (AGS3) is a newly identified protein shown to act at the level of the G protein itself. AGS3 belongs to the GoLoco family of proteins, sharing the 19-aa GoLoco motif that is a Galpha(i/o) binding motif. AGS3 interacts only with members of the Galpha(i/o) subfamily. By surface plasmon resonance, we found that AGS3 binds exclusively to the GDP-bound form of Galpha(i3). In GTPgammaS binding assays, AGS3 behaves as a guanine dissociation inhibitor (GDI), inhibiting the rate of exchange of GDP for GTP by Galpha(i3). AGS3 interacts with both Galpha(i3) and Galpha(o) subunits, but has GDI activity only on Galpha(i3), not on Galpha(o). The fourth GoLoco motif of AGS3 is a major contributor to this activity. AGS3 stabilizes Galpha(i3) in its GDP-bound form, as it inhibits the increase in tryptophan fluorescence of the Galpha(i3)-GDP subunit stimulated by AlF(4)(-). AGS3 is widely expressed as it is detected by immunoblotting in brain, testis, liver, kidney, heart, pancreas, and in PC-12 cells. Several different sizes of the protein are detected. By Northern blotting, AGS3 shows 2.3-kb and 3.5-kb mRNAs in heart and brain, respectively, suggesting tissue-specific alternative splicing. Taken together, our results demonstrate that AGS3 is a GDI. To the best of our knowledge, no other GDI has been described for heterotrimeric G proteins. Inhibition of the Galpha subunit and stimulation of heterotrimeric G protein signaling, presumably by stimulating Gbetagamma, extend the possibilities for modulating signal transduction through heterotrimeric G proteins.     

Genetics of Cardiac Electrical Disease

Few tragedies compare to the sudden death of a family member. Sadly, this may represent the first sign of a familial vulnerability to such events. One common cause is an inherited cardiac arrhythmia syndrome. Sufferers are prone to premature sudden cardiac death due to altered ion channel function in the heart. Typical causes include Brugada syndrome, long QT syndrome, short QT syndrome, catecholaminergic polymorphic ventricular tachycardia, and the newly recognized early repolarization syndrome. Our knowledge of the genetic underpinnings of each of these disorders has increased markedly in recent years. Genetic screening is now a routine part of clinical care and promises more accurate diagnosis and efficient family screening. This review summarizes the diagnosis and management of each of the listed syndromes in the context of currently available genetic testing.     

New associations of primary ciliary dyskinesia syndrome

Ten of 32 patients with primary ciliary dyskinesia syndrome (PCDS) also had other conditions. Five esophageal problems, 4 congenital heart disease, 2 scoliosis, and 4 miscellaneous and probably coincidental conditions were discovered. Additionally, a patient in this series, who has a normal heart, had a brother who died after surgery for complex congenital heart disease. In retrospect, he too probably had PCDS. The association of severe esophageal and cardiac disease with primary ciliary dyskinesia has not been described before. The diagnosis of PCDS may carry more implications than previously recognized. Pediatr Pulmonol. 1993; 16:9–12. © Wiley-Liss, Inc.     

Alagille syndrome and Wilson disease in siblings: a diagnostic conundrum

The authors describe two siblings, each with a different, rare genetic condition that affects liver function. The index case, the 18-year-old asymptomatic brother of a young man recently diagnosed with Wilson disease, presented for Wilson disease screening and was also found to have abnormal liver function suggestive of cholestasis. However, ceruloplasmin level, 24 h urine copper concentration and liver synthetic function were normal. Further hepatic investigations and genetic mutation analysis were performed, ultimately leading to a diagnosis of Alagille syndrome. He was treated with ursodiol, which resulted in normalization of his liver function tests. Subsequently, he was found to be a carrier for a mutation in the Wilson disease gene, ATP7B. In the present report, the potential implications of being a heterozygote for Wilson disease in the context of Alagille syndrome are discussed. Also stressed is that care must be exercised by the clinician when diagnosing family members who may present with two different disorders closely mimicking one another.     

Sudden death and ion channel disease: pathophysiology and implications for management

The underlying aetiology of sudden arrhythmic death syndrome is predominantly inherited cardiac disease, and 'channelopathies' (cardiac ion channel disease) are the most common detectable cause of death. This heterogeneous group includes Brugada syndrome, long QT syndrome and catecholaminergic polymorphic ventricular tachycardia. Common features include variable penetrance, sudden death due to ventricular arrhythmias, and the absence of structural heart disease. The understanding of cardiac ion channel disease has been revolutionised by genetics. At present, genotype contributes to risk stratification in Brugada syndrome, long QT syndrome and catecholaminergic polymorphic ventricular tachycardia, and the future promises management tailored to the genetic diagnosis.     

Brugada Syndrome: A Heterogeneous Disease with a Common ECG Phenotype?

Our understanding of Brugada syndrome (BrS) has evolved since the syndrome was first described in 1992. BrS is considered to be a primary inherited channelopathy often involving the inward sodium current and the diagnosis has traditionally required the exclusion of overt structural heart disease. In view of recently published observations about BrS, we propose that the term BrS may actually encompass a heterogeneous group of disorders with a variety of genetic and clinical phenotypes. This disease has classically been described as a primary electrical disorder involving the sodium channel leading to the characteristic electrocardiogram (ECG) changes of BrS. We challenge the current understanding and propose that patients with structurally normal hearts, family history of sudden cardiac death, with associated genetic abnormalities only account for a subset of patients with the “Brugada pattern” ECG. There may also be some patients with a diagnosis of BrS who may also have features which overlap with arrhythmogenic right ventricular cardiomyopathy. In these patients there may be an underlying structural abnormality. In this context, it is possible that catheter ablation may abolish the “Brugada pattern” ECG changes as well as abolishing the risk of life threatening arrhythmias in these patients. Given the recent developments in the field, we propose a novel comprehensive multimodality model for risk stratification and assessment of patients with BrS. Identification of variations of diseases may facilitate more specific risk stratification models and management paradigms in patients with Brugada ECG pattern.     

Inherited polyposis syndromes: molecular mechanisms, clinicopathology, and genetic testing.

The inherited polyposis syndromes are a group of conditions in which multiple gastrointestinal polyps occur in the lumen of the gastrointestinal tract, most exhibit an increased risk of colon cancer. Benign and malignant extraintestinal tumors might also be observed. Recent elucidation of the underlying gene mutations has contributed to our understanding of the cell biology and molecular mechanisms associated with gastrointestinal tumorigenesis. Developments have also allowed genetic testing to become an integral component in accurate diagnosis, categorization, and management of inherited polyposis syndromes. In this review, we will focus on familial adenomatous polyposis, mutY human homologue-associated polyposis, Peutz-Jeghers syndrome, juvenile polyposis, and Cowden syndrome. It is essential that both physician and patient understand the benefits and limitations of genetic testing before submission of samples to the laboratory. There are many issues accompanying molecular diagnosis of cancer syndromes, and genetic counseling is an essential prelude to genetic testing.     

The Current and Emerging Role of Cardiovascular Magnetic Resonance Imaging in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiomyopathy with substantial heterogeneity in phenotypic expression and clinical course. Traditionally, two-dimensional echocardiography has been the easiest and most reliable technique for establishing a diagnosis of HCM. However, cardiovascular magnetic resonance (CMR) has emerged as a novel, three-dimensional tomographic imaging technique, which provides high spatial and temporal resolution images of the heart in any plane and without ionizing radiation. As a result, CMR is particularly well suited to provide detailed characterization of the HCM phenotype, including precise assessment of the location and distribution of left ventricular (LV) wall thickening. In this regard, CMR can identify hypertrophy (particularly in the anterolateral free wall and apex), not well appreciated (or underestimated) by two-dimensional echocardiography, with important implications for diagnosis. CMR can also provide detailed characterization of other myocardial structures such as the papillary muscles, which may impact on preoperative management strategies for patients who are candidates for surgical myectomy. Furthermore, CMR enables an accurate assessment of total LV mass, a robust marker of the overall extent of hypertrophy, which may have implications for risk stratification. In addition, a subgroup of HCM patients have normal LV mass (with focal hypertrophy), suggesting that a limited extent of hypertrophy is consistent with a diagnosis of HCM. Finally, following the intravenous administration of gadolinium, first-pass perfusion sequences can identify myocardial perfusion abnormalities, while late gadolinium enhancement (LGE) sequences can characterize areas of myocardial fibrosis/scarring. LGE is associated with systolic dysfunction and likelihood for ventricular tachyarrhythmias on ambulatory Holter monitoring in patients with HCM. However, the precise clinical implications of myocardial perfusion abnormalities and LGE in HCM are still uncertain; this information may have important implications with regard to identifying HCM patients at risk of sudden death and adverse LV remodeling associated with systolic dysfunction. Therefore, at present, CMR provides important information impacting on diagnosis and clinical management strategies in patients with HCM and will likely have an expanding role in the evaluation of patients with this complex disease.     

Cardiomyopathies and Genetic Testing in Heart Failure: Role in Defining Phenotype-Targeted Approaches and Management

Cardiomyopathies represent an important cause of heart failure, often affecting young individuals, and have important implications for relatives. Genetic testing for cardiomyopathies is an established care pathway in contemporary cardiology practice. The primary cardiomyopathies where genetic testing is indicated are hypertrophic, dilated, arrhythmogenic, and restrictive cardiomyopathies, with left ventricular noncompaction as a variant phenotype. Early identification and initiation of therapies in patients with inherited cardiomyopathies allow for targeting asymptomatic and presymptomatic patients in stages A and B of the American College of Cardiology/American Heart Association classification of heart failure. The current approach for genetic testing uses gene panel–based testing with the ability to extend to whole-exome and whole-genome sequencing in rare instances. The central components of genetic testing include defining the genetic basis of the diagnosis, providing prognostic information, and the ability to screen and risk-stratify relatives. Genetic testing for cardiomyopathies should be coordinated by a multidisciplinary team including adult and pediatric cardiologists, genetic counsellors, and geneticists, with access to expertise in cardiac imaging and electrophysiology. A pragmatic approach for addressing genetic variants of uncertain significance is important. In this review, we highlight the indications for genetic testing in the various cardiomyopathies, the value of early diagnosis and treatment, family screening, and the care process involved in genetic counselling and testing.