Methods and materials for detecting fragile x mutations

A method for assessing Fragile X alleles in a mammal, said method comprising

• (a) amplifying nucleic acid obtained from said mammal to obtain amplified nucleic acid, wherein said amplified nucleic acid comprises a sequence from a regulatory region for a Fragile X polypeptide-encoding sequence, wherein said sequence comprises a CGG location flanked by a 3′ non-CGG sequence and a 5′ non-CGG sequence;
• (b) detecting the size of said amplified nucleic acid using a Southern blot and a oligonucleotide probe, wherein said oligonucleotide probe hybridizes to a repeated CGG sequence of said amplified nucleic acid, wherein the presence of a size diagnostic of greater than 200 CGG repeats at said CGG location in said amplified product indicates that said mammal comprises a Fragile X full mutant allele, wherein the presence of a size diagnostic of 59 to 199 CGG repeats at said CGG location in said amplified product indicates that said mammal comprises a Fragile X pre-mutation allele, wherein the presence of a size diagnostic of 45 to 58 CGG repeats at said CGG location in said amplified product indicates that said mammal comprises a Fragile X intermediate mutant allele, and wherein the presence of a size diagnostic of less than 45 CGG repeats at said CGG location in said amplified product indicates that said mammal comprises a non-mutant Fragile X allele.