Novel phenotype associated with homozygous likely pathogenic variant in the POP1 gene.

The biallelic variants of the POP1 gene are associated with the anauxetic dysplasia (AAD OMIM 607095), a rare skeletal dysplasia, characterized by prenatal rhizomelic shortening of limbs and generalized joint hypermobility. Affected individuals usually have normal neurodevelopmental milestones. Here we present three cases from the same family with likely pathogenic homozygous POP1 variant and a completely novel phenotype: a girl with global developmental delay and autism, microcephaly, peculiar dysmorphic features and multiple congenital anomalies. Two subsequent pregnancies were terminated due to multiple congenital malformations. Fetal DNA samples revealed the same homozygous variant in the POP1 gene. Expression of the RMRP was reduced in the proband compared with control and slightly reduced in both heterozygous parents, carriers for this variant. To our knowledge, this is the first report of this new phenotype, associated with a novel likely pathogenic variant in POP1. Our findings expand the phenotypic spectrum of POP1-related disorders.

Adeno-associated virus serotype 9 antibody titers in patients with SMA pre-screened for treatment with onasemnogene abeparvovec -routine care evidence.

Spinal muscular atrophy (SMA) is characterized by progressive weakness of skeletal and respiratory muscles. This study aimed to evaluate the prevalence of pre-existing anti adeno-associated virus serotype 9 antibody (AAV9-Ab) titers among infantile-onset SMA diagnosed infants pre-screened for treatment with AAV9-based onasemnogene abeparvovec, and to explore whether clinical and/or demographic characteristics are correlated with AAV9 Ab test results. This is a retrospective multicenter study of children diagnosed with 5q SMA younger than two years of age. The obtained data included demographic data, SMA type, SMN2 gene copy number, onset date, and results of AAV9-Ab test and of SMA prior treatments. Thirty-four patients were enrolled; six patients had positive results of AAV9-Ab (titer > 1:50) in the initial screening, 15 patients were re-tested for AAV9-Abs, of whom, three patients had seroreverted [1.5-4.5 months] between the two AAV9-Abs tests. One patient had seroconverted (5.5 months after the first AAV9-Abs test). The remaining 11 patients presented matching titer results in the two tests. No demographic/clinical factors were correlated to high AAV9-Abs titers (P > 0.05).We recommend AAV9-Ab re-tests to be performed until the age of 8 months, or, if 1.5 months or more have passed after the initial AAV9-Abs test.

Samaritan myopathy, an ultimately benign congenital myopathy, is caused by a RYR1 mutation.

Congenital myopathies describe a group of inherited muscle disorders with neonatal or infantile onset typically associated with muscle weakness, respiratory involvement and delayed motor milestones. We previously reported a novel congenital myopathy in an inbred Samaritan family. All patients displayed severe neonatal hypotonia and respiratory distress, and unlike other congenital myopathies, a constantly improving health status. As clinical and pathological data did not point to preferential candidate genes, we performed exome sequencing complemented by linkage analysis to identify the mutation causing the benign Samaritan congenital myopathy. We identified the homozygous p.Tyr1088Cys mutation in RYR1, encoding the skeletal muscle ryanodine receptor. This sarcoplasmic reticulum calcium channel is a key regulator of excitation-contraction coupling (ECC). Western blot and immunohistofluorescence revealed a significant decrease of the RYR1 protein level and an abnormal organization of skeletal muscle triad markers as caveolin-3, dysferlin and amphiphysin 2. RYR1 mutations are associated with different myopathies and malignant hyperthermia susceptibility. The index patient had mild hyperthermia following anesthesia, indicating that the inbred Samaritan population might be a risk group for this disorder. Our results suggest an aberrant ECC as the primary cause of this disease, and broaden the clinical consequences of RYR1 defects.

Genetic counseling and testing for FSHD (facioscapulohumeral muscular dystrophy) in the Israeli population.

Facioscapulohumeral muscular dystrophy (FSHD), is a dominantly inherited, late onset, progressive disease. At present, no treatment or prevention of symptoms are available. There is considerable clinical variability, even within families. The gene whose defect causes FSHD has not been identified, but molecular diagnosis can be made by analyzing D4Z4 repeat length on chromosome 4q35. The results can support or rule out the clinical diagnosis of FSHD, but there are also "gray zone", non-conclusive results. During the years 2000-6, 66 individuals (including 7 asymptomatic individuals), were tested in our institute for D4Z4 repeat number. In 77% of the cases the results were conclusive: two thirds of them supported a diagnosis of FSHD while in a third this diagnosis was ruled out. In 23% the results were in the gray zone. Cognitive involvement was rare, occurring only when the D4Z4 repeat size was very small (<15 kb). Maximal utilization of the existing molecular test for FSHD demands detailed clinical and family pedigree information. We recommend that comprehensive genetic counseling always be given before and after molecular testing for FSHD, in addition to the neurological follow-up. Presymptomatic testing should only be offered when complete molecular evaluation can be offered, including 4qA and 4qB variant analysis.

A benign congenital myopathy in an inbred Samaritan family.

We describe a novel form of myopathy in a mother and her two daughters from an inbred Samaritan family. The patients displayed severe neonatal hypotonia, lethargy and dysmorphic features. Motor milestones were delayed; however, the hypotonia and muscle weakness gradually improved during the first 2 years of life and independent walking was achieved by 18 months. The mother at the age of 23 years shows myopathic facies and minimal proximal weakness. Her intelligence is normal. Her muscle biopsy revealed central nuclei and disruption of the intermyofibrillary network with moth eaten and spiral fibers. Mutations in SMN, MTM1 and the myotonic dystrophy genes were excluded. We suggest this is a new benign form of congenital myopathy. Inheritance is probably autosomal recessive.

[Ketogenic diet as antiepileptic therapy: a description of the clinical experience and the multidisciplinary approach at the metabolic-neurogenetic clinic at the Wolfson Medical Center].

UNLABELLED: The ketogenic diet, built on a menu that includes a high fat content and low protein and carbohydrate percentages, constitutes an alternative therapy for children with refractory epilepsy. This study describes our clinical experience with the diet, its efficacy, and the adverse effects associated with this treatment modality, which is mainly indicated in patients who do not respond to conventional antiepileptic drugs (AEDs). We place particular emphasis on our multidisciplinary approach, which includes physicians, nurses, social workers, and dieticians. A chart review was performed on all pediatric patients who received the diet in our clinic between 1998 and 2003. We recorded the patients' demographic data, the age at epilepsy onset, the age of the patient at the time the diet was started, the characteristics of the epilepsy, the seizure frequency, the AEDs prior to and during the diet, the patient and family compliance, and the adverse effects. RESULTS: Ten patients were treated. The youngest patient was 8 months old and the oldest was 19 years old at the onset of the diet. Eight children suffered from a well-defined epileptic syndrome. All children had frequent seizures and received between 2 and 9 AEDs prior to the diet. The duration of the diet ranged between 6 weeks and two and a half years. Seven patients experienced over 50% seizure reduction while on the diet. However, total seizure control was not attained in any patient. Adverse effects were minimal. All the patients complied with this rigid diet in a good or excellent manner. Furthermore, we also observed an improvement in the degree of alertness, learning skills, and developmental milestones in most of the children. The diet failed to provide satisfactory seizure control or improvement in the well-being of 3 patients. In conclusion, the ketogenic diet is an effective therapeutic alternative for children with refractory epilepsy, irrespective of the patient's age, gender or disease duration. We attribute our therapeutic success with the diet to the multidisciplinary approach carried out in our clinic.

A new autosomal recessive syndrome with Zellweger-like manifestations.

A son and daughter of consanguineous Ashkenazi Jewish parents presented with phenotypic features that are typically seen in Zellweger syndrome: high forehead, broad nasal bridge, epicanthal fold, upslanting palpebral fissures, and micrognathia. In addition to the physical anomalies, they also have severe psychomotor retardation and hypotonia. However, results of peroxisomal studies including very long chain fatty acids and plasmalogen functions, were normal. There was partial deficiency of respiratory chain complexes. We suggest that this is a new autosomal recessive syndrome that could be due to a nuclear-encoded mitochondrial defect.