Last Updated: July 30, 2026 Introduction to Myotonic Dystrophy There are two major genetic forms of myotonic dystrophy, type 1 and type 2 (proximal myotonic myopathy). Both forms are the result of the acquisition of pathogenic expansion of nucleotide repeats. Type 1...
Last Updated: July 30, 2026 Introduction to Fragile XE Syndrome Fragile XE syndrome (previously referred to as fragile XE mental retardation) is an X-linked dominant disorder that is defined by patients who have the cytogenetic changes associated with fragile X...
Last Updated: July 30, 2026 Introduction to Fragile X Syndrome Fragile X syndrome is an X-linked dominant disorder representing the most common form of inherited intellectual impairment. Fragile X syndrome occurs with a frequency of approximately 1 in 4000 males and 1...
Last Updated: July 30, 2026 Introduction to Dentatorubral-Pallidoluysian Atrophy Dentatorubral-pallidoluysian atrophy (DRPLA) is a progressive neurodegenerative disease resulting from the expansion of a CAG trinucleotide repeat in the gene (ATN1) encoding the protein...
Last Updated: July 30, 2026 Introduction to the Spinocerebellar Ataxias The spinocerebellar ataxias (SCA) represent a group of autosomal dominant neurological disorders characterized by variable degrees of degeneration in the cerebellum, spinocerebellar tracts, and...
Last Updated: July 30, 2026 Introduction to Spinobulbar Muscular Atrophy Spinobulbar muscular atrophy (SBMA) is an adult onset, slowly progressive motor neuropathy that results from the expansion of a CAG trinucleotide repeat in exon 1 of the androgen receptor (AR)...
Last Updated: July 30, 2026 Introduction to Huntington Disease Huntington disease is inherited as an autosomal dominant disorder characterized by slowly progressive neurodegeneration associated with choreic movements (abnormal involuntary movements) and dementia. The...
Last Updated: July 30, 2026 Triplet Expansion Disorders The trinucleotide repeat disorders (also known as trinucleotide repeat expansion disorders or triplet repeat expansion disorders) represent a family of genetic disorders caused by an increase in the number of...
Last Updated: July 13, 2026 Introduction to Friedreich Ataxia Friedreich ataxia (FRDA) is an autosomal recessive disease named for Nicholas Friedreich who, in 1863, described a degenerative atrophy of the posterior columns of the spinal cord that resulted in a...