Last Updated: August 3, 2026 Introduction to Beckwith-Wiedemann Syndrome Beckwith-Wiedemann syndrome (BWS) is the most well characterized disorder affecting growth that results from defects in the process of genomic imprinting. The overall frequency of BWS is 1 in...
Last Updated December 16, 2025 Introduction to Prader-Willi Syndrome Prader-Willi syndrome (PWS) was first described in 1887 by John Langdon Down who also identified Down syndrome. The full spectrum of PWS was reported in 1956 by Andrea Prader, Alexis Labhart, and...
Last Updated: December 16, 2025 Introduction to Angelman Syndrome Angelman syndrome (AS) is named after the English physician Harry Angelman who first described the disorder in 1965. He observed three children with a similar constellation of symptoms and he referred...
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...