Barth syndrome is associated with a cognitive phenotype

OBJECTIVE: Barth syndrome is a rare, X-linked recessive disorder that affects only boys. The cardinal characteristics include growth retardation, cardioskeletal myopathy, chronic or cyclic neutropenia, and 3-methylglutaconic aciduria. A preliminary study of five young boys with Barth syndrome suggested a distinct cognitive phenotype. METHODS: The present study was designed to explore whether additional evidence for a cognitive phenotype emerged from a larger sample. A psychoeducational assessment battery was administered to 15 boys with Barth syndrome. Data from these boys were compared to data from 15 typically developing boys individually matched on age and grade in school to each of the 15 boys with Barth syndrome. RESULTS: Although boys with Barth syndrome had age-appropriate performance on all measures of reading-related skills, their performance on mathematics and visual spatial tasks was significantly lower than that of boys in the comparison group. Moreover, specific aspects of visual short-term memory also differed from available norms. CONCLUSION: Our findings support the validity of the preliminary findings and reflect a higher incidence of cognitive difficulties in boys with Barth syndrome relative to boys in the comparison group. Coupled with the fatigue regularly experienced by boys with Barth syndrome, our findings indicate that educational support should be implemented during the early school-age years for children with Barth syndrome.     

Cardiolipin deficiency in X-linked cardioskeletal myopathy and neutropenia (Barth syndrome,MIM 302060): a study in cultured skin fibroblasts

We determined cardiolipin concentrations in cultured skin fibroblasts of 5 patients with X-linked cardioskeletal myopathy and neutropenia (Barth syndrome, MIM 302060) and in two groups of control patients. High-performance liquid chromatography-electrospray mass spectrometry was used to quantify total cardiolipin and subclasses of cardiolipin molecular species in cultured skin fibroblasts. Total cardiolipin and cardiolipin subclasses were decreased in patients with Barth syndrome as compared with normal control patients and disease control patients. Patients with Barth syndrome have a specific decrease of various cardiolipin molecular species, foremost tetralineoyl-cardiolipin. Therefore the analysis of cardiolipin in fibroblasts offers a specific biochemical approach to detect this disorder.     

Barth Syndrome: An X-linked Cardiomyopathy with a Novel Mutation

The authors report a 6 yr old boy with Barth syndrome who presented with cardiomyopathy, neutropenia and hypotonia. Urine gas chromatography showed high level of 3-methylglutaconic acid. The DNA of both the patient and the mother showed a heterozygous 3 bp deletion in exon 8 of the tafazzin gene. This abnormality involves the deletion of the bases TGA starting at cDNA nucleotide 891 (c891_893delTGA), resulting in the absence of glutamic acid at codon 202 from a highly conserved area of the tafazzin protein, consistent with the diagnosis of Barth syndrome. This is the first case report of Barth syndrome in Arab population emphasizing the importance of detailed investigations in cases of hereditary cardiomyopathy.     

Differing clinical courses and outcomes in two siblings with Barth syndrome and left ventricular noncompaction

Barth syndrome is an X-linked disorder usually diagnosed in infancy. It is characterized by hypotonia, dilated cardiomyopathy, neutropenia, growth retardation, and 3-methylglutaconic aciduria. The syndrome is typically caused by mutations in the TAZ (G4.5) gene, which encodes a novel protein family called the tafazzins. We report the case of two brothers with Barth syndrome and left ventricular noncompaction (LVNC) caused by a splice donor mutation in TAZ. Both had impaired sucking ability at the age of 2 months. The elder brother was diagnosed with LVNC at the age of 4 months; by that time he had developed severe heart failure with metabolic decompensation. He died at 12 months of age due to intractable heart failure despite pharmacological therapy with diuretics, an angiotensin-converting enzyme inhibitor, and a beta-blocker. However, the younger brother, who was diagnosed as having Barth syndrome and LVNC with heart failure at the age of 2 months, received early medical treatment and demonstrated normal echocardiographic findings. Conclusion: The clinical courses of Barth syndrome observed in our cases show the phonotypic variability of this syndrome and suggest that early therapy may be beneficial for maintaining cardiac function.     

Genetic analysis of the G4.5 gene in families with suspected Barth syndrome.

Mutations have recently been identified in the G4.5 gene (Xq28), encoding the tafazzin protein, in patients with Barth syndrome. We performed mutational analysis in 5 families with suspected Barth syndrome. In 4 families a male child had all the cardinal features of this syndrome, and mutations of G4.5 were found in each case. A mutation was also found in a fifth family with an extensive history of early infant death from heart disease. The recognition of 5 unrelated families in 1 hospital during a 7-year period suggests that this disease may be underdiagnosed.     

Non-Epstein-Barr virus-associated T-cell lymphoma following cardiac transplantation for Barth syndrome

Barth syndrome is a metabolic disease characterized by infantile cardiomyopathy, neutropenia and organic aciduria. We report disease evolution in one of the first affected boys to undergo successful cardiac transplantation. CONCLUSION: Although cardiac status stabilized, he developed disabling skeletal myopathy, protracted lymphopenia and--5 y after transplant--fatal Epstein Barr (EBV)-negative T-cell non-Hodgkin's lymphoma.     

Successful mechanical circulatory support for 251 days in a child with intermittent severe neutropenia due to Barth syndrome

Barth syndrome is an X‐linked recessive disorder that is characterized by cardiomyopathy, variable neutropenia, skeletal myopathy, growth delay, and organic aciduria. The cardiac involvement typically results in a high risk of severe heart failure in infancy or early childhood. While Berlin Heart EXCOR is widely accepted as ventricular assistance in pediatric patients with end‐stage cardiac failure, infections remain a frequent and potentially severe complication. Therefore, the extended use of the device in the setting of intermittent or severe neutropenia is challenging. We present the case of a three‐yr child with Barth syndrome who was bridged successfully to transplant with a Berlin Heart EXCOR assist device for eight months (251 days) without major infectious complication, despite several episodes of severe neutropenia. This case demonstrates that prolonged mechanical circulatory support for a patient with neutropenia is feasible without important morbidity, with careful monitoring and a multidisciplinary approach. G‐CSF provides an excellent support in managing neutropenia.     

Cardiomyopathy in a child with neutropenia and motor delay

A 17-month boy with history of neutropenia and gross motor regression was found to have cardiomyopathy upon admission. He was diagnosed with Barth syndrome: dilated cardiomyopathy, neutropenia, skeletal myopathy, decreased stature, and 3-methylglutaconic aciduria, confirmed by tafazzin gene deletion. This diagnosis should be considered in boys with unexplained neutropenia.     

Barth syndrome without 3-methylglutaconic aciduria

Barth syndrome involves cardiomyopathy, skeletal myopathy, neutropenia and 3-methylglutaconic (3-mgc) aciduria. 3-mgc aciduria has been observed in almost all reported cases and has served as a diagnostic criterion. CONCLUSION: A case of confirmed BTHS, but without 3-mgc aciduria, emphasizes the importance of extensive investigations in cases with suspected hereditary cardiomyopathy.     

Successful cardiac transplantation in Barth syndrome--single-centre experience of four patients

We describe four patients with Barth syndrome who have undergone successful orthotopic heart transplantation. Patients are one, seven, 12.5 and 14.7 yr post-transplantation. One episode of severe infection occurred. Renal dysfunction and coronary allograft vasculopathy do not appear accelerated over non-Barth patients. Despite withholding purine synthesis inhibitors, these patients have not demonstrated an increased rate of rejection.     

Ventricular Arrhythmia in the X-linked Cardiomyopathy Barth Syndrome

Barth syndrome is an X-linked disorder characterized by dilated cardiomyopathy, cyclic neutropenia, skeletal myopathy, abnormal mitochondria, and growth deficiency. The primary defect is a mutation in the TAZ gene on the X chromosome at Xq28, resulting in abnormal phospholipid biosynthesis and cardiolipin deficiency. To date, there has been no systematic evaluation of the cardiac phenotype. We report five cases of cardiac arrest and/or placement of an internal cardiac defibrillator with documented ventricular arrhythmia. We suggest that ventricular arrhythmia is part of the primary phenotype of the disorder and that patients should be screened accordingly.     

Barth syndrome diagnosed in the subclinical stage of heart failure based on the presence of lipid storage myopathy and isolated noncompaction of the ventricular myocardium

Barth syndrome (BTHS) is an X-linked disorder characterized by skeletal myopathy, neutropenia, growth delay, and cardiomyopathy. It is caused by mutations in the tafazzin gene (TAZ). Although early diagnosis is critical to prevent the progression of heart failure, this disease remains unrecognized when heart failure is not clinically significant. Here we report on a 13-year-old boy with no family history of BTHS who was diagnosed with the syndrome in the subclinical stage of heart failure. The clues to the diagnosis of BTHS in this patient were the findings of lipid storage myopathy in the skeletal muscle biopsy, elevated plasma brain natriuretic peptide, and the diagnosis of isolated noncompaction of the ventricular myocardium in echocardiography. Genetic studies of TAZ revealed a disease-causing mutation (p.Gly216Arg) in this patient. Physicians should be aware of the possibility of this disease and carry out genetic studies when it is considered.     

Left Ventricular Noncompaction Cardiomyopathy in Barth Syndrome: An Example of an Undulating Cardiac Phenotype Necessitating Mechanical Circulatory Support as a Bridge to Transplantation

Barth syndrome (BTHS) is associated with myocardial disease, frequently left ventricular noncompaction cardiomyopathy, which may necessitate cardiac transplantation or lead to death in some patients. We report a child with BTHS who had an ??undulating cardiac phenotype?? and ultimately developed decompensated heart failure requiring mechanical circulatory support with a ventricular assist device as a bridge to transplantation. His course was complicated by acute lung injury requiring placement of an in-line oxygenator to maintain end-organ function. Not only was his course complicated by cardiac and respiratory failure but his BTHS associated comorbidities complicated the management of his therapy using mechanical assist device support. He was successfully supported and subsequently was transplanted. Here we discuss the management of a child with BTHS using mechanical circulatory support and describe the use of an in-line oxygenator, Quadrox, with the Berlin Excor device.     

Isolated Left Ventricular Noncompaction in a Newborn With Pierre-Robin Sequence

Pierre-Robin sequence or syndrome (PRS) (OMIM #261800) is characterized by a small mandible (micrognathia), posterior displacement/retraction of the tongue (glossoptosis), and upper airway obstruction. It has an incidence varying from 1 in 8,500 to 1 in 30,000 births. Congenital heart defects (CHDs) occur in 20 % of the patients with PRS. Ventricular septal defect, patent ductus arteriosus, and atrial septal defects are the most common lesions. Noncompaction of the ventricular myocardium is a rare cardiomyopathy characterized by a pattern of prominent trabecular meshwork and deep intertrabecular recesses. It is thought to be caused by arrest of the normal endomyocardial morphogenesis. Isolated left ventricular noncompaction (LVNC) in patients with PRS has not been reported previously. This report describes a newborn with PRS and isolated LVNC. Previously, LVNC has been reported in association with mitochondrial disorders, Barth syndrome hypertrophic cardiomyopathy, zaspopathy, muscular dystrophy type 1, 1p36 deletion, Turner syndrome, Ohtahara syndrome, distal 5q deletion, mosaic trisomy 22, trisomy 13, DiGeorge syndrome, and 1q43 deletion with decreasing frequency. Karyotype analysis of the reported patient showed normal chromosomes (46, XX), and a fluorescent in situ hybridization study did not show chromosome 22q11.2 deletion. This is the first clinical report of a patient with isolated LVNC and PRS. Noncompaction of the ventricular myocardium is a rare and unique disorder with characteristic morphologic features that can be identified by echocardiography. Long-term follow-up evaluation for development of progressive LV dysfunction and cardiac arrhythmias is indicated for these patients.     

Clinicopathologic conference: Barth Syndrome

A case of Barth Syndrome is presented and discussed by both clinician and pathologist, in this traditional clinico-pathologic conference. The current understanding of etiology is included, including elevation of 3-methylglutaconic acid (3MGC).     

Acute metabolic decompensation and sudden death in Barth syndrome: report of a family and a literature review

Barth syndrome presents in infancy with hypotonia, dilated cardiomyopathy, and neutropenia. We report a patient whose family history included two males who had died suddenly at the age of 15 days and 2 years, respectively. The index case presented with acute metabolic decompensation at 13 days of age. Within 8 h of presenting with metabolic acidosis (pH 7.13), lactic acidemia (18.5 mmol/l), hyperammonemia (375 mug/dl), hypoglycemia (25 mg/dl), and coagulopathy, the patient developed respiratory failure and required intubation. The diagnosis was established by the presence of left ventricular noncompaction and molecular analysis (c.C153G or Y51X mutation of the TAZ gene). The gene product, taffazin, is a homologue of the glycerolipid transferases involved in the phospholipid metabolism as tetralinoleoyl-cardiolipin, a component of the mitochondrial inner membrane. In conclusion, mutations in taffazin impair mitochondrial respiratory chain complexes, which may results in the acute metabolic decompensation and sudden death; cardiac transplantation is the only possibility at the present time.     

CLINICOPATHOLOGIC CONFERENCE: BARTH SYNDROME

A case of Barth Syndrome is presented and discussed by both clinician and pathologist, in this traditional clinico-pathologic conference. The current understanding of etiology is included, including elevation of 3-methylglutaconic acid (3MGC).     

Cardiac manifestations of inherited metabolic disease in children

Inborn errors of metabolism (IEM) are responsible for around 5% of all cases of cardiomyopathy (CM) and for 15% of non‐idiopathic cases. Storage disorders such as Pompe disease (glycogen storage disease type II) typically cause hypertrophic CM, whereas the accumulation of toxic metabolites, as seen in the organic acidurias, is associated with dilated cardiomyopathy (DCM). Mixed pathology is also possible, particularly in late presentations. IEM such as Barth syndrome, a disorder of cardiolipin stability usually associated with DCM, have been associated with rarer types of CM such as endocardial fibroelastosis and left ventricular non‐compaction. Conduction disturbances can also occur, particularly in disorders of glycogen metabolism associated with PRKAG2 mutations. Cardiac screening of patients with metabolic diseases is important to guide treatment and stratify risk. Supportive cardiac treatment may be required, and although associated myocardial disease may improve or even resolve with correction of the underlying metabolic disturbance, progression to cardiac transplantation has been described. In this article we document all IEM known to be associated with cardiac disease in children, focusing on common and clinically important diagnoses. We also discuss the pathophysiology of the various types of CM, and present a recommended approach to screening in the pediatric population.     

Eponym

Barth syndrome (OMIM #302060) (BTHS) is an X-linked disorder of lipid metabolism characterized by skeletal myopathy, neutropenia, growth delay, and cardiomyopathy. It is caused by mutations in the tafazzin gene (TAZ), which lead to decreased production of an enzyme required to produce cardiolipin, a component of the inner mitochondrial membrane necessary for proper functioning of the electron transport chain. The most common initial presentation of BTHS is significant heart failure due to cardiomyopathy, which is the main cause of death in infancy or childhood. On the other hand, some patients have limited clinical features of BTHS. These patients may be overlooked or misdiagnosed with unclassified congenital myopathy, especially when heart failure is not clinically significant. However, these patients could also develop significant heart failure or life-threatening arrhythmias during or even after childhood. Heart failure in BTHS is often responsive to standard medical therapy, indicating early diagnosis is critical. Diagnostic clues of BTHS in the subclinical stage of heart failure include family histories, findings of lipid storage myopathy in the skeletal muscle biopsy, and elevated plasma brain natriuretic peptide levels. The genetic analysis of TAZ is the only confirmatory method for the diagnosis of BTHS. Conclusion: physicians should be aware of the possibility of this disease and carry out genetic studies when it is considered.