Genetics of sporadic ALS

Area of Science:

• Genetics
• Neurodegenerative Diseases
• Biochemistry

Background:

• Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder.
• The CuZn-superoxide dismutase (CuZn-SOD) gene is the only known gene implicated in ALS.
• Numerous mutations in the CuZn-SOD gene have been identified since 1993.

Purpose of the Study:

• To review the mutations associated with ALS in the CuZn-SOD gene.
• To investigate the prevalence and inheritance patterns of specific mutations like D90A and I113T.
• To explore the possibility of familial ALS in cases diagnosed as sporadic due to low disease penetrance.

Main Methods:

• Literature review of published studies on CuZn-SOD gene mutations in ALS.
• Analysis of mutation data, including inheritance patterns (recessive/dominant) and penetrance.
• Statistical and genealogical examination of sporadic ALS cases.

Main Results:

• Eighty-nine disease-associated mutations in the CuZn-SOD gene have been reported.
• Fourteen of these mutations were found in patients with apparently sporadic ALS.
• The D90A mutation is frequent, showing both recessive and dominant inheritance, while I113T exhibits dominant inheritance with variable penetrance.
• Evidence suggests many sporadic ALS cases might be familial with reduced penetrance.

Conclusions:

• The CuZn-SOD gene plays a critical role in ALS pathogenesis.
• Understanding mutation types and inheritance patterns is crucial for ALS diagnosis.
• The concept of familial ALS should be considered even in apparently sporadic cases, especially when low penetrance is suspected.