Delayed appearance of 3-methylglutaconic aciduria in neonates with early onset metabolic cardiomyopathies: A potential pitfall for the diagnosis.

Infantile onset cardiomyopathies are highly heterogeneous with several phenocopies compared with adult cardiomyopathies. Multidisciplinary management is essential in determining the underlying etiology in children's cardiomyopathy. Elevated urinary excretion of 3-methylglutaconic acid (3-MGA) is a useful tool in identifying the etiology in some metabolic cardiomyopathy. Here, we report the delayed appearance of 3-MGA-uria, between 6 and 18 months in three patients (out of 100 childhood onset cardiomyopathy) with neonatal onset cardiomyopathy, secondary to TMEM70 mutations and TAZ mutations (Barth syndrome), in whom extensive metabolic investigations, performed in the first weeks of life, did not display 3-MGA-uria. Serial retrospective evaluations showed full characteristic features of TMEM70 and TAZ mutations (Barth syndrome) in these three patients, including a clearly abnormal monolysocardiolipin/cardiolipin ratio in the two Barth syndrome patients. Serially repeated metabolic investigations finally discovered the 3-MGA-uria biomarker in all three patients between the age of 6 and 18 months. Our observation provides novel insights into the temporal appearance of 3-MGA-uria in TMEM70 and TAZ mutations (Barth syndrome) and focus the importance of multidisciplinary management and careful evaluation of family history and red flag signs for phenocopies in infantile onset cardiomyopathies.

Differences in morbidity and mortality in Down syndrome are related to the type of congenital heart defect.

Morbidity and mortality in Down syndrome (DS) are mainly related to congenital heart defects (CHDs). While CHDs with high prevalence in DS (typical CHDs), such as endocardial cushion defects, have been extensively described, little is known about the impact of less common CHDs (atypical CHDs), such as aortic coarctation and univentricular hearts. In our single-center study, we analyzed, in observational, retrospective manner, data regarding cardiac features, surgical management, and outcomes of a cohort of DS patients. Literature review was performed to investigate previously reported studies on atypical CHDs in DS. Patients with CHDs were subclassified as having typical or atypical CHDs. Statistical analysis was performed for comparison between the groups. The study population encompassed 859 DS patients, 72.2% with CHDs, of which 4.7% were atypical. Statistical analysis showed a significant excess in multiple surgeries, all-cause mortality and cardiac mortality in patients with atypical CHDs (p = .0067, p = .0038, p = .0001, respectively). According to the Kaplan-Meier method, survival at 10 and 40 years was significantly higher in typical CHDs (99 and 98% vs. 91 and 84%, log rank <0.05). Among atypical CHDs, it seems that particularly multiple complex defects in univentricular physiology associate with a worse outcome. This may be due to the surgical difficulty in managing univentricular hearts with multiple defects concurring to the clinical picture or to the severity of associated defects themselves. Further studies need to address this specific issue, also considering the higher pulmonary pressures, infective complications, and potential comorbidities in DS patients.

LTBP2-related "Marfan-like" phenotype in two Roma/Gypsy subjects with the LTBP2 homozygous p.R299X variant.

Recessive variants in LTBP2 are associated with eye-restricted phenotypes including (a) primary congenital glaucoma and (b) microspherophakia/megalocornea and ectopia lentis with/without secondary glaucoma. Nosology of LTBP2 pathology in humans is apparently in contrast with the consolidated evidence of a wide expression of this gene in the developing embryo. Accordingly, in previously published patients with LTBP2-related eye disease, additional extraocular findings have been occasionally reported and include, among others, high-arched palate, tall stature, and variable cardiac involvement. Anyway, no emphasis was put on such systemic manifestations. Here, we report two unrelated Roma/Gypsy patients first ascertained for a multisystem disorder mainly characterized by primary congenital glaucoma, complex congenital heart defect, tall stature, long fingers, skin striae and dystrophic scarring, and resembling Marfan syndrome. Heart involvement was severe with polyvalvular heart dysplasia in one, and transposition of great arteries, thoracic arterial tortuosity, polyvalvular heart dysplasia, and neo-aortic root dilatation in the other. Both patients were homozygous for the recurrent c.895C>T[p.(R299X)] variant, typically found in individuals of Roma/Gypsy descent with an eye-restricted phenotype. Our findings point out LTBP2 as responsible of a systemic phenotype coherent with the community of syndromes related to anomalies in genes involved in the TGFß-pathway. Among these disorders, LTBP2-related systemic disease emerges as a distinct condition with expanding prognostic implications and autosomal recessive inheritance.

A heterozygous, intragenic deletion of CNOT2 recapitulates the phenotype of 12q15 deletion syndrome.

Only a few individuals with 12q15 deletion have been described, presenting with a disorder characterized by learning disability, developmental delay, nasal speech, and hypothyroidism. The smallest region of overlap for this syndrome was included in a genomic segment spanning CNOT2, KCNMB4, and PTPRB genes. We report on an additional patient harboring a 12q15 microdeletion encompassing only part of CNOT2 gene, presenting with a spectrum of clinical features overlapping the 12q15 deletion syndrome phenotype. We propose CNOT2 as the phenocritical gene for 12q15 deletion syndrome and its haploinsufficiency being associated with an autosomal dominant disorder, presenting with developmental delay, hypotonia, feeding problems, learning difficulties, nasal speech, skeletal anomalies, and facial dysmorphisms.

SOS1 mutations in Noonan syndrome: Cardiomyopathies and not only congenital heart defects! Report of six patients including two novel variants and literature review.

Noonan syndrome (NS) is caused by mutations in more than 10 genes, mainly PTPN11, SOS1, RAF1, and RIT1. Congenital heart defects and cardiomyopathy (CMP) are associated with significant morbidity and mortality in NS. Although hypertrophic CMP has "classically" been reported in association to RAF1, RIT1, and PTPN11 variants, SOS1 appears to be poorly related to CMP. Patients with NS attending our Center from January 2013 to June 2018 were eligible for inclusion if they carried SOS1 variants and presented with-or developed-CMP. Literature review describing the co-existence of SOS1 mutation and CMP was also performed. We identified six patients with SOS1 variants and CMP (male to female ratio 2:1) including two novel variants. CMP spectrum encompassed: (a) dilated CMP, (b) nonobstructive hypertrophic CMPs, and (c) obstructive hypertrophic CMPs. Survival is 100%. Literature review included 16 SOS1 mutated in CMP. CMP, mainly hypertrophic, has been often reported in association to RAF1, RIT1, and PTPN11 variants. Differently from previous reports, due to the frequent association of SOS1 variants and CMP in our single center experience, we suggest potential underestimated proportion of SOS1 in pediatric CMPs.

Tim/Timeless, a member of the replication fork protection complex, operates with the Warsaw breakage syndrome DNA helicase DDX11 in the same fork recovery pathway.

We present evidence that Tim establishes a physical and functional interaction with DDX11, a super-family 2 iron-sulfur cluster DNA helicase genetically linked to the chromosomal instability disorder Warsaw breakage syndrome. Tim stimulates DDX11 unwinding activity on forked DNA substrates up to 10-fold and on bimolecular anti-parallel G-quadruplex DNA structures and three-stranded D-loop approximately 4-5-fold. Electrophoretic mobility shift assays revealed that Tim enhances DDX11 binding to DNA, suggesting that the observed stimulation derives from an improved ability of DDX11 to interact with the nucleic acid substrate. Surface plasmon resonance measurements indicate that DDX11 directly interacts with Tim. DNA fiber track assays with HeLa cells exposed to hydroxyurea demonstrated that Tim or DDX11 depletion significantly reduced replication fork progression compared to control cells; whereas no additive effect was observed by co-depletion of both proteins. Moreover, Tim and DDX11 are epistatic in promoting efficient resumption of stalled DNA replication forks in hydroxyurea-treated cells. This is consistent with the finding that association of the two endogenous proteins in the cell extract chromatin fraction is considerably increased following hydroxyurea exposure. Overall, our studies provide evidence that Tim and DDX11 physically and functionally interact and act in concert to preserve replication fork progression in perturbed conditions.

Remember Friedreich ataxia even in a toddler with apparently isolated dilated (not hypertrophic!) cardiomyopathy. Revisited.

Friedreich ataxia (FRDA) is the most common form of ataxia in late childhood. Neurological manifestations often precede cardiac involvement, presenting mainly as hypertrophic cardiomyopathy. We describe a toddler with apparently isolated severe heart failure, successfully managed with heart transplant (HT). Although well described in adolescents and adults, onset of FRDA is very uncommon in toddlers and neurological ataxic features are predominant. The presenting symptom of cardiomyopathy is very rare. Similar history is rarely reported in literature, that we described, including an aggressive cardiomyopathy in children younger than 5 years-old. RESULTS: Our patient was diagnosed with FRDA at a postoperative stage due to minimal neurological manifestations. Moreover, the novelty of this study lies in demonstrating a major DNA triplet repeat expansion in skeletal muscle compared to DNA from peripheral blood leukocytes. These results support the concept that triplet repeat expansion is variable among different tissues in FRDA, and in our case it was more expanded in the post mitotic muscular tissue than in blood cells. We believe on the importance of taking in consideration this rare condition even in a toddler with apparently isolated cardiomyopathy and especially when conventional investigations give negative results. We discuss potential trigger effect of HT as a precipitating factor in manifesting neurological symptoms. This observation corresponds to our experience and relates to three patients described so far (the third patient died suddenly). Early onset cardiomyopathy with FRDA should increase awareness of this rare condition and we highlight HT successful outcome. Further reports are needed to delineate this rare condition in youngsters.

Insights into the Cardiac Phenotype in 9p Deletion Syndrome: A Multicenter Italian Experience and Literature Review.

Chromosome 9p deletion syndrome is a rare autosomal dominant disorder presenting with a broad spectrum of clinical features, including congenital heart defects (CHDs). To date, studies focused on a deep characterization of cardiac phenotype and function associated with this condition are lacking. We conducted a multicentric prospective observational study on a cohort of 10 patients with a molecular diagnosis of 9p deletion syndrome, providing a complete cardiological assessment through conventional echocardiography and tissue Doppler imaging echo modality. As a result, we were able to demonstrate that patients with 9p deletion syndrome without major CHDs may display subclinical cardiac structural changes and left-ventricle systolic and diastolic dysfunction. Albeit needing validation in a larger cohort, our findings support the idea that a complete cardiac assessment should be performed in patients with 9p deletion syndrome and should be integrated in the context of a long-term follow-up.

Cardiomyopathies in Children and Systemic Disorders When Is It Useful to Look beyond the Heart?

Cardiomyopathy (CMP) is a rare disease in the pediatric population, with a high risk of morbidity and mortality. The genetic etiology of CMPs in children is extremely heterogenous. These two factors play a major role in the difficulties of establishing standard diagnostic and therapeutic protocols. Isolated CMP in children is a frequent finding, mainly caused by sarcomeric gene variants with a detection rate that can reach up to 50% of analyzed cohorts. Complex multisystemic forms of pediatric CMP are even more heterogenous. Few studies in literature take into consideration this topic as the main core since it represents a rarity (systemic CMP) within a rarity (pediatric population CMP). Identifying etiology in this cohort is essential for understanding prognosis, risk stratification, eligibility to heart transplantation and/or mechanical-assisted procedures, preventing multiorgan complications, and relatives' recurrence risk calculation. The previous points represent a cornerstone in patients' empowerment and personalized medical care approach. The aim of this work is to propose a new approach for an algorithm in the setting of the diagnostic framework of systemic pediatric CMP. On the other hand, during the literature review, we noticed a relatively common etiologic pattern in some forms of complex/multisystem CMP. In other words, certain syndromes such as Danon, Vici, Alström, Barth, and Myhre syndrome share a common pathway of directly or indirectly defective "autophagy" process, which appears to be a possible initiating/triggering factor for CMPs. This conjoint aspect could be important for possible prognostic/therapeutic implications in this category of patients. However, multicentric studies detailed functional and experimental models are needed prior to deriving conclusions.

1p36 Deletion Syndrome and the Aorta: A Report of Three New Patients and a Literature Review.

BACKGROUND: Monosomy 1p36 syndrome is now considered the most common terminal deletion syndrome, with an estimated incidence of 1 in 5000. Cardiac involvement is well described in the literature mainly in terms of congenital heart defects (CHDs) and cardiomyopathies (CMPs). Few data in the literature describe the potential progressive nature of aortic dilatation (root and ascending aorta) in 1p36 deletion syndrome. SKI harboured in the deleted region might play a predisposing factor for this aspect. METHODS: we reviewed the aortic aspect both in the literature and in our cohort, where major attention to the aortic abnormalities was given through dedicated echocardiographic measurements even in previously screened individuals. RESULTS: aortic involvement in 1p36 deletion syndrome was described in the literature three times within the CHD context. We observed three additional patients from our cohort (three out of nine patients) with aortic dilatation. All patients with dilated aorta had SKI haploinsufficiency within the deleted region. CONCLUSIONS: at long-term outcome and with a growing population of this rare disease, this association (1p36 deletion and aortic dilatation) might represent a major concern especially in terms of risk stratification and the potential need for specific management (conservative pharmacologic and eventually surgical) whenever indicated. The present study suggests the need for detailed multicentric studies and indication to periodic echocardiographic screening in addition to baseline tests, especially in individuals with deletions harbouring SKI.