Expression study of survival motor neuron gene in human fetal tissues

In order to investigate the spinal muscular atrophy (SMA) disease processes, the expression of the survival motor neuron gene (SMN) has been analyzed in human fetal tissues using RT-PCR and in situ hybridization. These studies allowed the detection of SMN RNA in all the examined tissues, with no significant variation between different developmental stages. In particular, SMN mRNA was detected in spinal cord (dorsal and ventral portions), skeletal muscle, lung, heart, kidney, liver, and spleen. Moreover, RT-PCR studies demonstrated that the expression pattern of SMN isoforms was similar to that observed in adult tissues. The present data confirm a housekeeping role for the SMN protein and may have implications on the search for early therapeutic strategies.

A possible role of NAIP gene deletions in sex-related spinal muscular atrophy phenotype variation

Childhood SMAs are common neuromuscular disorders, due to the occurrence of large genomic deletions encompassing the SMN gene and often extending to involve the NAIP gene. Although NAIP deletions are more frequently observed in patients affected by the acute form of the disease, it is not possible to establish an unambiguous correlation between deletion size and clinical severity. We have investigated the effects of gender on the association between NAIP gene deletion and disease severity. NAIP deletions were screened in 197 Italian SMA patients lacking SMN; the results obtained were correlated with disease severity in male and female samples separately. No significant relationship between deletion size and clinical phenotype was observed among male subjects, whereas in females the absence of NAIP was strongly associated with a severe phenotype (p <0.0001). These results provide a possible molecular explanation for the sex-dependent phenotype variation observed in SMA patients.

Influence des ions sur le pouvoir hydratant de l'ure e: e tude sur peau de porc ex vivo

This study deals with the influence of ions (NaCl and MgSO4) in a W/O emulsion containing 10% urea. Moisturization kinetics are assessed by corneometry on pig skin ex vivo. The formula's influence on urea penetration is measured by infrared spectrometry with an ATR device and the stripping method. Corneometry and spectroscopy were chosen to record simultaneously the hydratation levels and urea localization into superficial cell layers. Urea crystallization after evaporation of emulsions and aqueous solutions is described. Results show that urea does not hydrate nor penetrate when applied to the skin through an aqueous gel. In a W/O emulsion, sodium chloride increases the ability of urea to moisturize without improving penetration. In vitro urea crystallization is disturbed by sodium chloride or magnesium sulphate for solutions and emulsions. This stabilization by ions is correlated with good moisturization values. The stabilization of urea in the solute state provided by ions increases its water epidermal binding capacity without enhancing penetration.

Discordant clinical outcome in type III spinal muscular atrophy sibships showing the same deletion pattern

Three type III spinal muscular atrophy (SMA) families are described in which the same deletion pattern for SMN gene and flanking loci is apparent in both affected and unaffected siblings. Deletions extending to include the NAIP gene are reported in one sibship. All three individuals in which SMN and/or NAIP deletions were detected showed the same haplotypes for SMA linked microsatellite markers as their affected sibs. The three index cases had a SMA III with early onset (1.5-2 yr) and became chairbound at the age 4, 5 and 20 yr. The three haploidentical sibs were given a clinical severity score. One of them showed no sign of the disease at the age of 4 yr and was considered "unaffected"; a 35-yr-old female, who had no symptoms but showed tongue fasciculations and hand tremor was considered "asymptomatic"; a 34-yr-old female, who had mild muscular weakness since the age of 24, was rated "mild". These observations demonstrate the presence of a continuum of clinical variability within SMA III families. These data suggest that, in these three families at least, the SMA phenotype is caused or influenced by another gene(s) additional to SMN.

Deletion analysis of the simple tandem repeat loci physically linked to the spinal muscular atrophy locus

Multicopy dinucleotide repeats have been characterized in the spinal muscular atrophy (SMA) region on chromosome 5q13, which reveal deletions in some SMA patients. 119 Italian and Spanish SMA families have been analysed using the C272 and C212 markers. Seventy percent of these families were informative. We found 9.4% de novo deletions in SMA I and 1.5% in SMA II families. A single inherited deletion segregating in a Spanish pedigree was detected in three affected brothers. A SMA II patient showed deletion only of C272. The data presented in this study are relevant to the molecular diagnosis of SMA families in Italy and Spain and provide additional insights toward the understanding of the molecular pathology of SMA.

Survival motor neuron gene transcript analysis in muscles from spinal muscular atrophy patients

We have identified and characterized four different mRNA isoforms of the survival motor neuron (SMN) gene from skeletal muscle of 9 SMA patients and 15 unaffected controls. These isoforms appear to be generated by combinatorial splicing of both exons 5 and 7 of the SMN telomeric and centromeric gene copies. The full-size and the truncated SMN-1b isoforms of the telomeric SMN copy are significantly reduced in muscle of SMA patients, irrespective of the disease types. Our results suggest that multiple RNA splicing is operative in the two SMN-related genes and that SMN-related polypeptides may be active in the muscle.

Neonatal spinal muscular atrophy with diaphragmatic paralysis is unlinked to 5q11.2-q13

Two sibs affected by the severe neonatal form of spinal muscular atrophy (SMA) with diaphragmatic paralysis are described. The two sibs were discordant for the haplotypes determined by DNA markers flanking the SMA locus. This supports non-linkage of SMA to chromosome 5 in this family and indicates that the uncommon SMA type I variant associated with early onset respiratory failure maps outside the 5q11.2-q13.3 region.

Identification of multiple transcribed sequences from the spinal muscular atrophy region of human chromosome 5

We report the isolation and characterization of novel expressed sequences from the spinal muscular atrophy (SMA) region on human chromosome 5q13. Based on the sequence homology studies these cDNAs were grouped in four classes, one of which shows extensive homologies with the beta-glucuronidase (BG) gene, differing in exon arrangement. The other cDNAs do not show any strong homology with known DNA sequences.

First-trimester prenatal diagnosis of spinal muscular atrophy using microsatellite markers

Twenty-five pregnancies at risk for spinal muscular atrophy I (SMA I) have been monitored by first-trimester prenatal diagnosis. Microsatellite markers were used in all cases to amplify polymorphic regions at the D5S125, D5S435, D5S39, D5S127, and D5S112 loci. All families, including 12 SMA I pedigrees with a decreased index child, were fully informative for DNA analysis. Three fetuses were predicted to be affected and 22 fetuses were predicted to be unaffected. Twenty-two newborns were unaffected by clinical examination at birth. These results support the accuracy of SMA I prenatal diagnosis based on linkage analysis.

A tool for the molecular analysis of an early lethal disease: slide-PCR in spinal muscular atrophy patients

DNA was recovered from sections of muscle biopsies of 20 spinal muscular atrophy (SMA) patients fixed on microscopic slides and stored from one to 20 years at room temperature. Microsatellite DNA markers tightly linked to the SMA locus were amplified using the polymerase chain reaction (PCR) to obtain specific amplified products. The procedure was successful in all cases, and allowed prenatal diagnosis in one at-risk pregnancy. In our hands this procedure is quick, sensitive and reproducible.