الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
This is a cohort study included 14 families of 50 members who were subjected to molecular genetic testing PCR-RFLP analysis for DNA and Semi- Quantitative PCR of SMN1 exon 7 and albumin gene as reference gene. To sum up our work revealed that firstly, multiple sib affection (multiplex families) was noted in most of the cases. Relatives shared some genotypic features to the probands yet they have different phenotypes i.e. asymptomatic carriers. Clinically asymptomatic individuals with tested SMN percent should be followed for protracted intervals for evaluation of muscle status to early detect those with minimal affect. Those individuals should be subjected for more accurate testing using copy number. 2ndly, there was a link between the percent of SMN and clinical severity as manifested by mild clinical manifestation and later age of onset of group II which is associated with more than 10% SMN. This inverse relationship should be expressed clinically with caution, as there is no available statistical testing due to limited number of cases, which is considered as a limitation of generalization to that conclusion. Finally, since other investigation done for SMA diagnosis mostly be normal, molecular genetic testing is mandatory for diagnosis of SMA focusing on determining SMN1 and SMN2 copy number. Molecular genetic testing for SMN with stress on copy number remains the definitive diagnostic modality of SMA as the other diagnostic modalities e.g., EMG could be non-specific.