Improving detection and genetic counseling in carriers of spinal muscular atrophy with two copies of the SMN1 gene.

Spinal muscular atrophy (SMA) is an autosomal recessive disease caused by mutations in the survival motor neuron1 gene (SMN1). Global carrier frequency is around 1 in 50 and carrier detection is crucial to define couples at risk to have SMA offspring. Most SMA carriers have one SMN1 copy and are currently detected using quantitative methods. A few, however, have two SMN1 genes in cis (2/0 carriers), complicating carrier diagnosis in SMA. We analyzed our experience in detecting 2/0 carriers from a cohort of 1562 individuals, including SMA parents, SMA relatives, and unrelated individuals of the general population. Interestingly, in three couples who had an SMA child, both the parents had two SMN1 copies. Families of this type have not been previously reported. Our results emphasize the importance of performing a detailed carrier study in SMA parents with two SMN1 copies. Expanding the analysis to other key family members might confirm potential 2/0 carriers. Finally, when a partner of a known carrier presents two SMN1 copies, the study of both parents will provide a more accurate diagnosis, thus optimizing genetic counseling.

The c.859G>C variant in the SMN2 gene is associated with types II and III SMA and originates from a common ancestor.

Homozygous mutations of the telomeric SMN1 gene lead to degeneration of motor neurons causing spinal muscular atrophy (SMA). A highly similar centromeric gene (SMN2) can only partially compensate for SMN1 deficiency. The c.859G>C variant in SMN2 has been recently reported as a positive disease modifier. We identified the variant in 10 unrelated chronic SMA patients with a wide spectrum of phenotypes ranging from type II patients who can only sit to adult walkers. Haplotype analysis strongly suggests that the variant originated from a common ancestor. Our results confirm that the c.859G>C variant is a milder SMN2 allele and predict a direct correlation between SMN activity and phenotypic severity.

Chemopreventive efficacy of curcumin and piperine during 7,12-dimethylbenz[a]anthracene-induced hamster buccal pouch carcinogenesis.

INTRODUCTION: Oral carcinoma accounts for 40-50 percent of all cancers in India. Tobacco chewing, smoking and alcohol consumption are the major risk factors associated with the high incidence of oral cancer in India. Our aim was to investigate the chemopreventive potential of curcumin and piperine during 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch carcinogenesis. METHODS: Oral squamous cell carcinoma was developed in the buccal pouch of Syrian golden hamsters, by painting them with 0.5 percent DMBA in liquid paraffin, three times a week for 14 weeks. The tumour incidence, tumour volume and burden were determined in the buccal pouches. The status of phase II detoxification agents, lipid peroxidation and antioxidants were estimated by specific colorimetric methods. RESULTS: We observed 100 percent tumour formation in DMBA-alone painted hamsters. Disturbances in the status of lipid peroxidation, antioxidants and phase II detoxification agents were noticed in DMBA-alone painted hamsters. Oral administration of curcumin (80 mg/kg body weight) and piperine (50 mg/kg body weight) to DMBA-painted hamsters on alternate days to DMBA painting for 14 weeks completely prevented the formation of oral carcinoma. Also, curcumin and piperine restored the status of lipid peroxidation, antioxidants and detoxifying agents in DMBA-painted hamsters. CONCLUSION: The chemopreventive efficacy of curcumin and piperine is probably due to their antilipidperoxidative and antioxidant potential as well as their modulating effect on the carcinogen detoxification process.