Left-ventricular non-compaction in a patient with monosomy 1p36

1p36 Deletion Syndrome and Left Ventricular Non-compaction Cardiomyopathy-Two Cases Report

1p36 deletion is the most common terminal deletion syndrome in humans. Herein, we report two cases, a 5-month-old female and a 14.5-year-old female, both with 1p36 deletion and left ventricular non-compaction cardiomyopathy. They presented with severely depressed left ventricle function and underwent heart transplantation with excellent outcomes. Given the incidence of heart defects and cardiomyopathy in 1p36 deletion syndrome, it should be recommended that children with this genetic condition have screening for cardiac disease. These cases add to the current literature by demonstrating the potential therapeutic options for non-compaction in 1p36 deletion syndrome and showed the favorable outcomes.

Electroclinical features of epilepsy associated with 1p36 deletion syndrome: A review

1p36 terminal deletion is a recently recognized syndrome with multiple congenital anomalies and intellectual disability. It occurs approximately in 1 out of 5000 to 10,000 live births and is the most common subtelomeric microdeletion observed in human. Medical problems commonly caused by terminal deletions of 1p36 include developmental delay, intellectual disability, seizures, vision problems, hearing loss, short stature, brain anomalies, congenital heart defects, cardiomyopathy, renal anomalies and distinctive facial features. Although the syndrome is considered clinically recognizable, there is significant phenotypic variation among affected individuals. Genotype-phenotype correlation in this syndrome is complicated, because of the similar clinical evidence seen in patients with different deletion sizes. We review 34 scientific articles from 1996 to 2016 that described 315 patients with 1p36 delection syndrome. The aim of this review is to find a correlation between size of the 1p36-deleted segments and the neurological clinical phenotypes with the analysis of electro-clinical patterns associated with chromosomal aberrations, that is a major tool in the identification of epilepsy susceptibility genes. Our finding suggest that developmental delay and early epilepsy are frequent findings in 1p36 deletion syndrome that can contribute to a poor clinical outcome for this reason this syndrome should be searched for in patients presenting with infantile spasms associated with a hypsarrhythmic EEG, particulary if they are combined with dismorphic features, severe hypotonia and developmental delay.

Microarray analysis of 50 patients reveals the critical chromosomal regions responsible for 1p36 deletion syndrome-related complications

OBJECTIVE

Monosomy 1p36 syndrome is the most commonly observed subtelomeric deletion syndrome. Patients with this syndrome typically have common clinical features, such as intellectual disability, epilepsy, and characteristic craniofacial features.

METHOD

In cooperation with academic societies, we analyzed the genomic copy number aberrations using chromosomal microarray testing. Finally, the genotype-phenotype correlation among them was examined.

RESULTS

We obtained clinical information of 86 patients who had been diagnosed with chromosomal deletions in the 1p36 region. Among them, blood samples were obtained from 50 patients (15 males and 35 females). The precise deletion regions were successfully genotyped. There were variable deletion patterns: pure terminal deletions in 38 patients (76%), including three cases of mosaicism; unbalanced translocations in seven (14%); and interstitial deletions in five (10%). Craniofacial/skeletal features, neurodevelopmental impairments, and cardiac anomalies were commonly observed in patients, with correlation to deletion sizes.

CONCLUSION

The genotype-phenotype correlation analysis narrowed the region responsible for distinctive craniofacial features and intellectual disability into 1.8-2.1 and 1.8-2.2 Mb region, respectively. Patients with deletions larger than 6.2 Mb showed no ambulation, indicating that severe neurodevelopmental prognosis may be modified by haploinsufficiencies of KCNAB2 and CHD5, located at 6.2 Mb away from the telomere. Although the genotype-phenotype correlation for the cardiac abnormalities is unclear, PRDM16, PRKCZ, and RERE may be related to this complication. Our study also revealed that female patients who acquired ambulatory ability were likely to be at risk for obesity.

Monoamniotic monochorionic twins discordant for noncompaction cardiomyopathy

Occasionally "identical twins" are phenotypically different, raising the question of zygosity and the issue of genetic versus environmental influences during development. We recently noted monochorionic-monoamniotic twins, one of which had an isolated cardiac abnormality, noncompaction cardiomyopathy, a condition characterized by cardiac ventricular hypertrabeculation. We examined the prenatal course and subsequent pathologic correlation since ventricular morphogenesis may depend on early muscular contraction and blood flow. The monochorionic-monoamniotic female twin pair was initially identified since one fetus presented with increased nuchal translucency. Complete heart block was later identified in the fetus with nuchal translucency who did not survive after delivery. In contrast, the unaffected twin had normal cardiac studies both prenatally and postnatally. Pathologic analysis of the affected twin demonstrated noncompaction of the left ventricle with dysplasia of the aortic and pulmonary valves. Dissection of the cardiac conduction system disclosed atrioventricular bundle fibrosis. Maternal lupus studies, amniocentesis with karyotype, and studies for 22q11.2 were normal. To test for zygosity, we performed multiple STR marker analysis and found that all markers were shared even using nonblood tissues from the affected twin. These studies demonstrate that monozygotic twins that are monochorionic monoamniotic can be discordant for cardiac noncompaction. The results suggest further investigation into the potential roles of pathologic fibrosis, contractility, and blood flow in cardiac ventricle development.

Cardiomyopathy in neurological disorders

According to the American Heart Association, cardiomyopathies are classified as primary (solely or predominantly confined to heart muscle), secondary (those showing pathological myocardial involvement as part of a neuromuscular disorder) and those in which cardiomyopathy is the first/predominant manifestation of a neuromuscular disorder. Cardiomyopathies may be further classified as hypertrophic cardiomyopathy, dilated cardiomyopathy, restrictive cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, or unclassified cardiomyopathy (noncompaction, Takotsubo-cardiomyopathy). This review focuses on secondary cardiomyopathies and those in which cardiomyopathy is the predominant manifestation of a myopathy. Any of them may cause neurological disease, and any of them may be a manifestation of a neurological disorder. Neurological disease most frequently caused by cardiomyopathies is ischemic stroke, followed by transitory ischemic attack, syncope, or vertigo. Neurological disease, which most frequently manifests with cardiomyopathies are the neuromuscular disorders. Most commonly associated with cardiomyopathies are muscular dystrophies, myofibrillar myopathies, congenital myopathies and metabolic myopathies. Management of neurological disease caused by cardiomyopathies is not at variance from the same neurological disorders due to other causes. Management of secondary cardiomyopathies is not different from that of cardiomyopathies due to other causes either. Patients with neuromuscular disorders require early cardiologic investigations and close follow-ups, patients with cardiomyopathies require neurological investigation and avoidance of muscle toxic medication if a neuromuscular disorder is diagnosed. Which patients with cardiomyopathy profit most from primary stroke prevention is unsolved and requires further investigations.

Noncompaction of the ventricular myocardium and hydrops fetalis in cobalamin C disease

Cobalamin C disease (cblC), a form of combined methylmalonic acidemia and hyperhomocysteinemia caused by mutations in the MMACHC gene, may be the most common inborn error of intracellular cobalamin metabolism. The clinical manifestations of cblC disease are diverse and range from intrauterine growth retardation to adult onset neurological disease. The occurrence of structural heart defects appears to be increased in cblC patients and may be related to the function of the MMACHC enzyme during cardiac embryogenesis, a concept supported by the observation that Mmachc is expressed in the bulbis cordis of the developing mouse heart. Here we report an infant who presented with hydrops fetalis, ventricular dysfunction, and echocardiographic evidence of LVNC, a rare congenital cardiomyopathy. Metabolic evaluations, complementation studies, and mutation analysis confirmed the diagnosis of cblC disease. These findings highlight an intrauterine cardiac phenotype that can be displayed in cblC disease in association with nonimmune hydrops.

Left ventricular hypertrabeculation/noncompaction with epilepsy, other heart defects, minor facial anomalies and new copy number variants

Background

Left ventricular hypertrabeculation/noncompaction (LVHT) is a cardiac abnormality of unknown etiology which has been described in children as well as in adults with and without chromosomal aberrations. LVHT has been reported in association with various cardiac and extracardiac abnormalities like epilepsy and facial dysmorphism.

Case presentation

A unique combination of LVHT, atrial septal defect, pulmonary valve stenosis, aortic stenosis, epilepsy and minor facial anomalies is presented in a 5.5 years old girl. Microarray-based genomic hybridization (array-CGH) detected six previously not described copy number variants (CNVs) inherited from a clinically unaffected father and minimally affected mother, thus, most likely, not clinically significant but rare benign variants.

Conclusions

Despite this complex phenotype de novo microdeletions or microduplications were not detected by array CGH. Further investigations, such as whole exome sequencing, could reveal point mutations and small indels as the possible cause.

New Genetic Insights into Congenital Heart Disease

There has been remarkable progress in understanding the genetic basis of cardiovascular malformations. Chromosome microarray analysis has provided a new tool to understand the genetic basis of syndromic cardiovascular malformations resulting from microdeletion or microduplication of genetic material, allowing the delineation of new syndromes. Improvements in sequencing technology have led to increasingly comprehensive testing for aortopathy, cardiomyopathy, single gene syndromic disorders, and Mendelian-inherited congenital heart disease. Understanding the genetic etiology for these disorders has improved their clinical recognition and management and led to new guidelines for treatment and family-based diagnosis and surveillance. These new discoveries have also expanded our understanding of the contribution of genetic variation, susceptibility alleles, and epigenetics to isolated congenital heart disease. This review summarizes the current understanding of the genetic basis of syndromic and non-syndromic congenital heart disease and highlights new diagnostic and management recommendations.

Copy number variants and infantile spasms: evidence for abnormalities in ventral forebrain development and pathways of synaptic function

Infantile spasms (ISS) are an epilepsy disorder frequently associated with severe developmental outcome and have diverse genetic etiologies. We ascertained 11 subjects with ISS and novel copy number variants (CNVs) and combined these with a new cohort with deletion 1p36 and ISS, and additional published patients with ISS and other chromosomal abnormalities. Using bioinformatics tools, we analyzed the gene content of these CNVs for enrichment in pathways of pathogenesis. Several important findings emerged. First, the gene content was enriched for the gene regulatory network involved in ventral forebrain development. Second, genes in pathways of synaptic function were overrepresented, significantly those involved in synaptic vesicle transport. Evidence also suggested roles for GABAergic synapses and the postsynaptic density. Third, we confirm the association of ISS with duplication of 14q12 and maternally inherited duplication of 15q11q13, and report the association with duplication of 21q21. We also present a patient with ISS and deletion 7q11.3 not involving MAGI2. Finally, we provide evidence that ISS in deletion 1p36 may be associated with deletion of KLHL17 and expand the epilepsy phenotype in that syndrome to include early infantile epileptic encephalopathy. Several of the identified pathways share functional links, and abnormalities of forebrain synaptic growth and function may form a common biologic mechanism underlying both ISS and autism. This study demonstrates a novel approach to the study of gene content in subjects with ISS and copy number variation, and contributes further evidence to support specific pathways of pathogenesis.

Recurrent interstitial 1p36 deletions: Evidence for germline mosaicism and complex rearrangement breakpoints

Deletions of chromosome 1p36 are one of the most frequently encountered subtelomeric alterations. Clinical features of monosomy 1p36 include neurocognitive impairment, hearing loss, seizures, cardiac defects, and characteristic facial features. The majority of cases have occurred sporadically, implying that genomic instability plays a role in the prevalence of the syndrome. Here, we report two siblings with mild phenotypic features of the deletion syndrome, including developmental delay, hearing loss, and left ventricular non-compaction (LVNC). Microarray analysis using bacterial artificial chromosome and oligonucleotide microarrays indicated the deletions were identical, suggesting germline mosaicism. Parental phenotypes were normal, and analysis by fluorescence in situ hybridization (FISH) did not show mosaicism. These small interstitial deletions were not detectable by conventional subtelomeric FISH analysis. To investigate the mechanism of deletion further, the breakpoints were cloned and sequenced, demonstrating the presence of a complex rearrangement. Sequence analysis of genes in the deletion interval did not reveal any mutations on the intact homologue that may have contributed to the LVNC seen in both children. This is the first report of apparent germline mosaicism for this disorder. Thus, our findings have important implications for diagnostic approaches and for recurrence risk counseling in families with a child with monosomy 1p36. In addition, our results further refine the minimal critical region for LVNC and hearing loss.

Left ventricular non-compaction on MRI in a patient with 22q11.2 distal deletion

We report on a 22-year-old male carrying a presumptive clinical diagnosis of Dubowitz-like phenotype who has been followed-up by cardiology for bicuspid aortic valve with ascending aorta and aortic root dilatation. Cardiac magnetic resonance imaging (CMRI) confirmed these findings, along with an incidental finding of left ventricular non-compaction (LVNC). Genetic workup revealed the diagnosis of 22q11.2 distal deletion encompassing the BCR gene. This is the first time LVNC has been reported in a patient with 22q11.2 distal deletion.

Epilepsy and chromosomal abnormalities

Background

Many chromosomal abnormalities are associated with Central Nervous System (CNS) malformations and other neurological alterations, among which seizures and epilepsy. Some of these show a peculiar epileptic and EEG pattern. We describe some epileptic syndromes frequently reported in chromosomal disorders.

Methods

Detailed clinical assessment, electrophysiological studies, survey of the literature.

Results

In some of these congenital syndromes the clinical presentation and EEG anomalies seems to be quite typical, in others the manifestations appear aspecific and no strictly linked with the chromosomal imbalance. The onset of seizures is often during the neonatal period of the infancy.

Conclusions

A better characterization of the electro clinical patterns associated with specific chromosomal aberrations could give us a valuable key in the identification of epilepsy susceptibility of some chromosomal loci, using the new advances in molecular cytogenetics techniques - such as fluorescent in situ hybridization (FISH), subtelomeric analysis and CGH (comparative genomic hybridization) microarray. However further studies are needed to understand the mechanism of epilepsy associated with chromosomal abnormalities.

Cardiogenetics, neurogenetics, and pathogenetics of left ventricular hypertrabeculation/noncompaction

BACKGROUND

Left ventricular hypertrabeculation (LVHT), also known as noncompaction or spongy myocardium, is a cardiac abnormality of unknown etiology and pathogenesis frequently associated with genetic cardiac and noncardiac disorders, particularly genetic neuromuscular disease. This study aimed to review the current knowledge about the genetic or pathogenetic background of LVHT.

METHODS

A literature review of all human studies dealing with the association of LVHT with genetic cardiac and noncardiac disorders, particularly neuromuscular disorders, was conducted.

RESULTS

Most frequently, LVHT is associated with mitochondrial disorders (mtDNA, nDNA mutations), Barth syndrome (G4.5, TAZ mutations), hypertrophic cardiomyopathy (MYH7, ACTC mutations), zaspopathy (ZASP/LDB3 mutations), myotonic dystrophy 1 (DMPK mutations), and dystrobrevinopathy (DTNA mutations). More rarely, LVHT is associated with mutations in the DMD, SCNA5, MYBPC3, FNLA1, PTPN11, LMNA, ZNF9, AMPD1, PMP22, TNNT2, fibrillin2, SHP2, MMACHC, LMX1B, HCCS, or NR0B1 genes. Additionally, LVHT occurs with a number of chromosomal disorders, polymorphisms, and not yet identified genes, as well in a familial context. The broad heterogeneity of LVHT's genetic background suggests that the uniform morphology of LVHT not only is attributable to embryonic noncompaction but also may result from induction of hypertrabeculation as a compensatory reaction of an impaired myocardium.

CONCLUSIONS

Most frequently, LVHT is associated with mutations in genes causing muscle or cardiac disease, or with chromosomal disorders. These associations require comprehensive cardiac, neurologic, and cytogenetic investigations.

Left-ventricular non-compaction (LVNC): a clinical feature more often observed in terminal deletion 1p36 than previously expected

Deletion of 1p36 (OMIM 607872) is estimated to be the most common distal terminal deletion syndrome. We describe a previously unreported, typically affected two-month-old girl with this microdeletion syndrome, who additionally suffers from left-ventricular non-compaction (LVNC). Recently, this congenital heart defect, characterized by prominent left-ventricular trabeculae and deep intertrabecular recesses, was reported in 12 further patients (excluding those reported only in abstract form) with terminal deletion of 1p36, leading to the conclusion that this cardiomyopathy is common in patients with this chromosomal aberration. We hypothesize that a gene in 1p36 might be responsible for LVNC.

Noncompaction of the left ventricle: primary cardiomyopathy with an elusive genetic etiology

PURPOSE OF REVIEW

Noncompaction of the left ventricle is a descriptive anatomical term and recently recognized primary cardiomyopathy. Cardiac imaging now allows for prompt detection. The specific etiology remains poorly understood, however, and the major genetic determinants are unknown. This review describes recent data showing the genetic heterogeneity and overlap with other cardiomyopathies. Understanding the genetics may depend on clarifying the distinctive diagnostic features and investigating the contribution of all known cardiomyopathy-causing genes with overlapping morphology.

RECENT FINDINGS

Adding to the known genes (TAZ, DTNA, LDB3 and LMNA), recent work has identified SCN5A, MYH7 and MYBPC3 as associated loci. LDB3 may also be a genetic modifier. Case reports and linkage studies suggest additional loci at 1p36, 1q43 and 11p15. Aside from Barth syndrome, other genetic and metabolic syndromes with noncompaction have been described. Despite this, large studies have failed to identify the etiology in the majority of patients.

SUMMARY

Despite advances in detection, comprehensive clinical, pathological, genetic, and family studies are necessary to define the phenotypic overlap with other cardiomyopathies. Without a more precise understanding of its etiology, the answers to the questions regarding the clinical relevance and management of patients with noncompaction of the left ventricle will remain elusive.