Available Assays

Clinical laboratories use several strategies to incorporate mutation studies into their screening programs. Some laboratories initially screen by enzyme analysis and follow with mutation studies for individuals with a result in the carrier or inconclusive ranges, while other laboratories use DNA studies alone for selected populations. DNA studies are performed used a variety of methods, including PCR amplification followed by allele-specific oligonucleotide (ASO) hybridization or restriction enzyme digestion, allele-specific amplification, TaqMan probe technologies, or ligation chain reaction amplification.

In Ashkenazi Jewish individuals, there are two common mutations in HEXA associated with infantile TSD and one associated with an adult-onset form of the disease. A 4 base pair insertion (TATC) in exon 11 accounts for approximately 80% of mutant alleles in this population, and a splice defect in intron 12 (IVS12+1G^C) accounts for another 15%. A missense mutation, G269S, leads to an adult-onset form of TSD and accounts for approximately 2% of carriers.

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