Two cases of severe neonatal hypertrophic cardiomyopathy caused by compound heterozygous mutations in the MYBPC3 gene.

BACKGROUND: Idiopathic (primary) hypertrophic cardiomyopathy (HCM) is mainly caused by mutations in genes encoding sarcomeric proteins. One of the most commonly mutated HCM genes is the myosin binding protein C (MYBPC3) gene. Mutations in this gene lead mainly to truncation of the protein which gives rise to a relatively mild phenotype. Pure HCM in neonates is rare and most of the time childhood HCM occurs in association with another underlying condition. OBJECTIVE: To study the presence of mutations in the MYBPC3 gene in idiopathic childhood HCM. METHODS: MYBPC3 coding region and splice junction variation were analysed by denaturing high performance liquid chromatography (DHPLC) and sequencing in DNA isolated from two neonates with severe unexplained HCM, who died within the first weeks of life. RESULTS: Truncating mutations were found in both alleles of the MYBPC3 gene in both patients, suggesting there was no functional copy of the MYBPC3 protein. Patient 1 carried the maternally inherited c.2373_2374insG mutation and the paternally inherited splice-donor site mutation c.1624+1G-->A. Patient 2 carried the maternally inherited frameshift mutation c.3288delA (p.Glu1096fsX92) and the paternally inherited non-sense mutation c.2827C-->T (p.Arg943X). CONCLUSIONS: The findings indicate the need for mutation analysis of genes encoding sarcomeric proteins in childhood HCM and the possibility of compound heterozygosity.

Normal very-long-chain fatty acids in peroxisomal D-bifunctional protein deficiency: a diagnostic pitfall.

We present a relatively mild case of peroxisomal D-bifunctional protein deficiency with inconsistent screening results in plasma for peroxisomal disorders.

Possible bradycardic mode of death and successful pacemaker treatment in a large family with features of long QT syndrome type 3 and Brugada syndrome.

INTRODUCTION: We recently identified a novel mutation of SCN5A (1795insD) in a large family with features of both long QT syndrome type 3 and the Brugada syndrome. The purpose of this study was to detail the clinical features and efficacy of pacemaker therapy in preventing sudden death in this family. METHODS AND RESULTS: The study group consisted of 116 adult family members: 60 carriers (29 males) and 56 noncarriers (28 males) of the mutant gene. Investigations included 24-hour Holter monitoring, ergometry, and electrophysiologic studies. Mean, lowest, and highest heart rate were lower in the carriers, but heart rate variability was comparable. In carriers, disproportional QT prolongation was present during bradycardia. No complex ventricular ectopy was recorded, and there were fewer isolated premature beats (both ventricular and atrial) in carriers. All patients were asymptomatic, except for two individuals who experienced syncope; in one of these patients, asystolic episodes (up to 9 sec) were repeatedly recorded. Prolonged HV intervals were present in 5 of 6 patients. Thirty carriers received a prophylactic backup pacemaker. During median follow-up of 4.5 years (range 0.0 to 22.6), their survival rate was 100%. There were five sudden deaths among the remaining 30 carriers without a pacemaker (P = 0.019). CONCLUSION: This family with a high incidence of nocturnal sudden death is characterized by bradycardia-dependent QT prolongation, intrinsic sinus node dysfunction, and generalized conduction abnormalities. There is a striking absence of complex ventricular ectopy, and pacemaker implantation was effective in preventing sudden death. These findings raise the possibility of a bradycardic rather than tachycardic mode of death.

Maternal uniparental disomy for chromosome 14 in a boy with a normal karyotype.

We report on a boy with a maternal uniparental disomy for chromosome 14 (UPD(14)). At 7 years of age he was referred to us by the paediatrician because of symptoms of Prader-Willi syndrome (PWS). He showed short stature, obesity, mild developmental delay, cryptorchidism, and some mild dysmorphic features. The history further indicated intrauterine growth retardation at the end of the pregnancy. His mother was 44 years of age at the time of his birth. After birth he showed hypotonia with poor sucking, for which gavage feeding was needed. Motor development was delayed. After 1 year he became obese despite a normal appetite. Recurrent middle ear infections, a high pain threshold, and a great skill with jigsaw puzzles were reported. There were no behavioural problems or sleep disturbance. Chromosomal analysis was normal (46,XY). DNA analysis for Prader-Willi syndrome showed no abnormalities. Two years later he was re-examined because we thought his features fitted the PWS-like phenotype associated with maternal UPD(14). At that time precocious puberty was evident. DNA analysis showed maternal heterodisomy for chromosome 14. In all the previously described 11 cases with maternal UPD(14), a Robertsonian translocation involving chromosome 14 was detected cytogenetically before DNA analysis. This is the first report of diagnosis of maternal UPD(14) based on clinical features. This finding underlines the importance of DNA analysis for maternal UPD(14) in patients with a similar PWS-like phenotype even without previous identification of a Robertsonian translocation involving chromosome 14.

Perlman syndrome: four additional cases and review.

Perlman syndrome was first described in 1973 and comprises nephromegaly with renal dysplasia and Wilms tumor, macrosomia, cryptorchidism, and multiple facial anomalies. Polyhydramnios and hypoglycaemia are often found. Twelve children have been described from six different families. Five came from one family whose Yemenite Jewish parents were second cousins. Autosomal recessive inheritance has been suggested. Prognosis is severe with neonatal death in most children. We report on 4 new cases of Perlman syndrome from 3 families; all parents were non-consanguineous. Some of the observed manifestations have been described only once in this syndrome (cardiac defect, hepatic fibrosis with portoportal bridging, haemangioma) or never before (volvulus, intestinal atresia, and agenesis of the corpus callosum in 1 patient, a cleft palate in another). All children died within the first year. The 2 sibs were born prematurely with nephromegaly but without hamartomas or nephroblastomatosis. This is consistent with the hypothesis that dysplastic medullary parenchyma in preterm infants develops into nephroblastomatosis and hamartoma and eventually Wilms tumor.

[Syndromes 16. Osteogenesis imperfecta]. / Syndromen 16. Osteogenesis imperfecta.

Osteogenesis imperfecta consists of a group of hereditary connective tissue diseases with fragility of the bone as a general feature. Frequently occurring other characteristics are blue sclerae, opalescent teeth, hearing loss, disorders of the skeleton, and hyperextensibility of the joints. Obliteration and the unusual shape of the pulp chambers may interfere with dental treatment.

Prenatal and postnatal investigation of a case with Miller-Dieker syndrome due to a familial cryptic translocation t(17;20) (p13.3;q13.3) detected by fluorescence in situ hybridization.

We present here a case report of a fetus with a kidney anomaly and dilated occipital horns, detected initially by echoscopy at 29 weeks' amenorrhoea. After 31 weeks of gestation, the proband was born with clinical symptoms of Miller-Dieker syndrome. This was subsequently confirmed by fluorescence in situ hybridization (FISH), but not by conventional cytogenetic analysis. FISH using a cocktail of cosmids (c197-2, c197-4, c197-9) from the Miller-Dieker critical region showed a deletion of 17p13.3 in one homologue of chromosome 17. Additional FISH studies revealed a subtle 17p;20q translocation in the father, his sister, and the paternal grandmother. Hence, our patient is a carrier of an unbalanced 17;20 translocation resulting in a partial deletion of 17p and a partial trisomy 20q. Whenever kidney anomalies and dilated occipital horns are observed together with polyhydramnios during prenatal ultrasound examination, the possibility of Miller-Dieker syndrome should be suspected. In such cases, prenatal and/or postnatal chromosome studies should also include FISH analysis with the appropriate probes.

Refinement by linkage analysis in two large families of the candidate region of the third locus (SCA3) for autosomal dominant cerebellar ataxia type I.

The autosomal dominant cerebellar ataxias (ADCA) are clinically and genetically heterogeneous. To date, several loci (SCAI-V) have been identified for ADCA type I. We have studied two large families from the northern part of The Netherlands with ADCA type I with a broad intra-familial variation of symptoms. In both families significant linkage is shown of the disease to the markers of the SCA3 locus on chromosome 14. Through recombinations, the candidate region for SCA3 could be refined to a 13-cM range between D14S256 and D14S81. No recombinations were detected with the markers D14S291 and D14S280, which suggests that the SCA3 gene lies close to these loci. This finding will benefit the individuals at risk in these two families who are seeking predictive testing or prenatal diagnosis.