Cardiac alpha-myosin (MYH6) is the predominant sarcomeric disease gene for familial atrial septal defects.

Secundum-type atrial septal defects (ASDII) account for approximately 10% of all congenital heart defects (CHD) and are associated with a familial risk. Mutations in transcription factors represent a genetic source for ASDII. Yet, little is known about the role of mutations in sarcomeric genes in ASDII etiology. To assess the role of sarcomeric genes in patients with inherited ASDII, we analyzed 13 sarcomeric genes (MYH7, MYBPC3, TNNT2, TCAP, TNNI3, MYH6, TPM1, MYL2, CSRP3, ACTC1, MYL3, TNNC1, and TTN kinase region) in 31 patients with familial ASDII using array-based resequencing. Genotyping of family relatives and control subjects as well as structural and homology analyses were used to evaluate the pathogenic impact of novel non-synonymous gene variants. Three novel missense mutations were found in the MYH6 gene encoding alpha-myosin heavy chain (R17H, C539R, and K543R). These mutations co-segregated with CHD in the families and were absent in 370 control alleles. Interestingly, all three MYH6 mutations are located in a highly conserved region of the alpha-myosin motor domain, which is involved in myosin-actin interaction. In addition, the cardiomyopathy related MYH6-A1004S and the MYBPC3-A833T mutations were also found in one and two unrelated subjects with ASDII, respectively. No mutations were found in the 11 other sarcomeric genes analyzed. The study indicates that sarcomeric gene mutations may represent a so far underestimated genetic source for familial recurrence of ASDII. In particular, perturbations in the MYH6 head domain seem to play a major role in the genetic origin of familial ASDII.

Efficiency of transcatheter closure of atrial septal defects in small and symptomatic children.

OBJECTIVES: We report the multicentric French experience with transcatheter closure in children weighing 15 kilograms or less, with the aim of assessing the efficacy of the procedure in this age group. PATIENTS: We included all children weighing 15 kilograms or less, and seen between January, 1997, and June, 2004, who had successful transcatheter closure of an interatrial communication within the oval fossa. RESULTS: Transcatheter closure was performed in 35 patients weighing 15 kilograms or less, of whom 14 were male and 21 female. The procedures were undertaken in 8 different centres, the patients having a median age of 3 years, with a range from zero to 6.2 years, and a mean weight of 13 kilograms, with a range from 3.6 to 15 kilograms. All the patients were symptomatic, with associated cardiac malformations present in 4 cases, and extracardiac anomalies in 4 patients, including Down's syndrome in 3, and Adams Oliver syndrome in the other case. In 1 patient, emergency cardiac surgery was needed 24 h after the procedure to correct a previously undiagnosed divided right atrium. No other complication occurred. After a median follow-up of 2 years, with a range from 0.5 to 5.2 years, all the patients are asymptomatic, except for one long-standing patient with bronchodysplasia. In 1 other patient, a small residual bidirectional shunt was detected by echocardiography. No patient presented significant arrhythmia. In the patients followed-up for more than 12 months, we found a significant gain in weight gain. CONCLUSION: Transcatheter closure of an interatrial communication within the oval fossa is efficient in children weighing 15 kilograms or less, and can be proposed as a first line of treatment in symptomatic patients. Children with retarded growth tend to have complete recovery within one year of closure.

A third case of cardiac neoplasm in a fetus with Beckwith-Wiedemann syndrome: epicardial angiofibroma.

OBJECTIVE: A personal observation of a 20-week-old fetus with Beckwith-Wiedemann syndrome (BWS) presenting epicardial angiofibroma prompted us to evaluate cardiac neoplasms in this genetic condition. METHOD: We performed an autopsy and a histological evaluation of the fetus, and searched the literature for cardiac anomalies in BWS. RESULTS: Although cardiac tumors are exceptional and although BWS is rare, we found two other cardiac neoplasms in infants with BWS, whereas no more than one was expected. CONCLUSION: Besides an excess of cardiac malformation, BWS seems to favor an excess of cardiac tumors, which may occur very early.

Pallister-Killian syndrome: difficulties of prenatal diagnosis.

The first prenatal diagnosis of Pallister-Killian syndrome (PKS) was reported by Gilgenkrantz et al. in1985. Since this report, about 60 prenatal cases have been reported but both sonographic and cytogenetic diagnoses remain difficult. Although ultrasound anomalies such as congenital diaphragmatic hernia, polyhydramnios and rhizomelic micromelia in association with fetal overgrowth are very suggestive of the syndrome, they are inconstant and they may even be absent. The mosaic distribution of the supernumerary isochromosome 12p greatly increases these difficulties. No prenatal cytogenetic technique is sensitive enough to ensure prenatal diagnosis and false-negative results have been described on fetal blood, chorionic villi and amniocentesis. We report here two prenatal cases of PKS which illustrate the great variability of the fetal phenotype. In reviewing the 63 reported cases, we attempt to determine ultrasound indicators of the syndrome and to define a cytogenetic strategy. In cases where ultrasound indicators are present, our proposal is first to perform chorionic villus or placental sampling and then amniocentesis when the first cytogenetic result is normal. Fetal blood sampling is the least indicated method because of the low frequency of the isochromosome in lymphocytes. In this cytogenetic strategy, fluorescent in situ hybridization (FISH) and especially interphase FISH on non-cultured cells increases the probability or identifying the isochromosome. A misdiagnosis remains possible when ultrasound is not contributory; the identification of new discriminating ultrasound indicators would be very helpful in this context.