Ruth Shomrat

Prevalence of glucocerebrosidase mutations in the Israeli Ashkenazi Jewish population.

Gaucher disease is the most prevalent inherited disease among Ashkenazi Jews. It is very heterogeneous due to a large number of mutations within the glucocerebrosidase gene, whose impaired activity is the cause for this disease. Aiming at determining Gaucher carrier frequency among the Ashkenazi Jewish population in Israel, 1,208 individuals were molecularly diagnosed for six mutations known to occur among Ashkenazi Jewish Gaucher patients, using the newly developed Pronto™ Gaucher kit. The following mutations were tested: N370S, 84GG, IVS2+1, D409H, L444P, and V394L. Molecular testing of these mutations also allows identification of the recTL allele. The results indicated that Gaucher carrier frequency is 1:17 within the tested population. The prevalence of N370S carriers is 1:17.5. This implies that ˜1:1225 Ashkenazi Jews will be homozygous for the N370S mutation. Actually, in our study of 1,208 individuals one was found to be homozygous for the N370S mutation. The actual number of known Ashkenazi Jewish Gaucher patients with this genotype is much lower than that expected according to the frequency of the N370S mutation, suggesting a low penetrance of this mutation. Results of loading experiments in cells homozygous for the N370S mutation, as well as cells homozygous for the L444P and the D409H mutations, exemplified this phenomenon. Hum Mutat 12:240–244, 1998.

Rett Syndrome: Clinical Manifestations in Males With MECP2 Mutations

Rett syndrome is a neurodevelopmental disorder characterized by cognitive and adaptive regression with autistic features, loss of acquired skills, and stereotypic hand movements that almost exclusively affects females. It is an X-linked dominant disorder, with presumed lethality in males. Nonetheless, there are a few descriptions of males suspected of having Rett syndrome. With the recent discovery that the MECP2 gene is responsible for most cases of Rett syndrome, it is possible to molecularly assess cases of affected males by direct sequencing analysis. We describe an Israeli family consisting of a female having classic Rett syndrome and a male sibling with severe neonatal encephalopathy. Molecular analysis revealed that both sister and brother have the same MECP2 gene mutation; however, their mother does not. This case, as well as other published studies of males with MECP2 mutations, reveals that the clinical manifestations in viable males vary from neonates with severe encephalopathy to adults with mental retardation and demonstrate genotype-phenotype correlations. (J Child Neurol 2002;17:20-24).

Clinical and genetic heterogeneity of congenital adrenal hypoplasia due to NR0B1 gene mutations.

Introduction  X‐linked adrenal hypoplasia congenita (AHC) is a rare disorder caused by mutations or complete deletion of the NR0B1 gene that encodes the DAX‐1 protein, an orphan member of the nuclear receptor superfamily. AHC is characterized by adrenal insufficiency in infancy and early childhood. Later, hypogonadotropic hypogonadism (HH) manifests as pubertal failure.

Fetal muscle biopsy as a diagnostic tool in Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a relentless progressive disorder, leading to severe disability during childhood and death in adolescence or early adulthood. In most families, prenatal diagnosis is readily achieved by molecular detection of DNA deletions using chorionic villi or amniocytes, or by linkage analysis. In some cases, however, molecular methods fail to provide a definitive diagnosis and in such cases in utero fetal muscle biopsy may serve as a diagnostic option. We describe three families in whom fetal muscle biopsy was performed, focusing on the prenatal diagnostic dilemmas, the indications and timing for in utero fetal muscle biopsy, and the difficulties encountered. Copyright

Predictive value of TP53 fluorescence in situ hybridization in cytogenetic subgroups of acute myeloid leukemia

Acute myeloid leukemia (AML) with a complex karyotype (CK) has frequent alterations in TP53 and a very poor prognosis. We examined whether a prompt and simple fluorescence in situ hybridization (FISH) analysis for 17p13 deletion at diagnosis has a predictive value for response to therapy and overall survival in subgroups of AML. In 15 patients with a normal karyotype the TP53 FISH analysis was normal, whereas in 16 patients with CK 75% had only one copy of the TP53 allele. The deletion was also detected in 33% of six patients with monosomy or partial monosomy of chromosome 5, 7, 9, or 12. This loss of TP53 correlated significantly with a poor response to chemotherapy, and the median survival time of these patients was shorter. TP53 FISH analysis carried out at diagnosis has a predictive value with respect to chemotherapy response and can therefore facilitate a rapid decision on treatment strategies.

SMA type 2 unrelated to chromosome 5q13.

We describe two brothers with clinical and histological findings of type 2 spinal muscular atrophy (SMA) associated with small head circumference (<2%) and normal cognitive development. No survival motor neuron (SMN) or neuronal apoptosis-inhibitory protein (NAIP) deletions were detected in these sibs, and they were discordant for the haplotypes determined by DNA markers flanking the 5q13 SMA locus. These findings support the presence of a distinct anterior horn disease unrelated to 5q13. This entity may have either autosomal recessive or X-linked inheritance.