Related Experiment Video
Updated: Jul 18, 2026
06:33
Genetic Analysis of Hereditary Transthyretin Ala97Ser Related Amyloidosis
Published on: June 9, 2018
Allan-Herndon syndrome. I. Clinical studies
R E Stevenson1, H O Goodman, C E Schwartz
1Greenwood Genetic Center and Self Memorial Hospital, SC 29646.
American Journal of Human Genetics
|September 1, 1990
Summary
Allan-Herndon syndrome is an X-linked disorder causing severe mental retardation, muscle hypoplasia, and spastic paraplegia in males. This study reinvestigated the original family, confirming its distinct clinical features across seven generations.
Area of Science:
- Genetics and Neurology
- X-linked inheritance patterns
- Neurodevelopmental disorders
Background:
- Reinvestigation of a large family with X-linked mental retardation, first described by Allan, Herndon, and Dudley in 1944.
- Focus on a specific X-linked disorder affecting multiple generations.
Observation:
- Twenty-nine males across seven generations were affected.
- Clinical presentation includes severe mental retardation, dysarthria, ataxia, athetoid movements, muscle hypoplasia, and spastic paraplegia.
- Distinct facial features: elongated facies, normal head circumference, bitemporal narrowing, and large ears; joint contractures develop.
Findings:
- The condition, named Allan-Herndon syndrome, is characterized by a specific constellation of neurological and motor deficits.
- Normal statural growth, absence of macroorchidism, and unimpaired longevity were noted.
- High-resolution chromosome analysis, serum creatine kinase, and amino acid levels were within normal limits, aiding in differential diagnosis.
Implications:
- Allan-Herndon syndrome is distinguished from other X-linked intellectual disability disorders.
- Further research into the genetic basis and molecular mechanisms of Allan-Herndon syndrome is warranted.
- Understanding this syndrome contributes to the broader knowledge of X-linked neurological disorders and their clinical management.
Related Concept Videos
01:30Acute Coronary Syndrome III: Diagnostic Studies
Diagnosing acute coronary syndrome or ACS begins with a thorough patient history. Notable symptoms include central, crushing chest pain radiating to the left arm, neck, jaw, or back, along with shortness of breath, sweating (diaphoresis), nausea, vomiting, dizziness, and palpitations.It is crucial to note any history of cardiac illnesses and assess risk factors, including age, gender, smoking, hypertension, diabetes, hyperlipidemia, and a sedentary lifestyle.During physical examination, vital...
01:30Hypertension III: Clinical Manifestations and Diagnostic Studies
Hypertension is asymptomatic and also referred to as the "silent killer" until it progresses to a severe stage or causes target organ disease. Patients may experience symptoms stemming from the strain on blood vessels and tissues in various organs or the heart's increased workload.Physical exams might show no abnormalities other than high blood pressure. Signs of vascular damage, when present, correspond to the organs supplied by the affected vessels, leading to target organ damage. For...
01:21Aneurysm II: Clinical Manifestations and Diagnostic Studies
Thoracic, aortic arch and abdominal aneurysms are significant vascular conditions that can present with various clinical manifestations and lead to serious complications. Understanding these manifestations and the appropriate diagnostic studies is essential for effective management and treatment.Thoracic Aortic AneurysmsThoracic aortic aneurysms often remain asymptomatic until they reach a size that impinges on adjacent structures. They typically cause deep, diffuse chest pain that radiates to...
01:26Cushing Syndrome I: Introduction
Cushing syndrome refers to the collection of clinical manifestations that arise when tissues are exposed to excessive amounts of cortisol or cortisol-like medications over an extended period. Cortisol, a glucocorticoid produced by the adrenal cortex, regulates metabolism, immune responses, and the body’s adaptation to stress. When its concentration remains chronically elevated, these physiological pathways become dysregulated, resulting in the characteristic features of the syndrome.Exogenous...
01:19Cushing Syndrome II: Pathophysiology
Cortisol production is normally governed by the hypothalamic–pituitary–adrenal (HPA) axis, which maintains hormonal balance through tightly regulated feedback mechanisms. Disruption of this regulatory system is central to the development of Cushing syndrome, whether the excess cortisol originates from external medications or internal pathology. Persistent cortisol elevation alters metabolism, immune function, and endocrine signaling, producing the characteristic clinical features of the...
01:21Huntington Disease l: Introduction
Huntington disease or HD is a progressive, fatal neurodegenerative disorder inherited in an autosomal dominant pattern.PathophysiologyIt is caused by expansion of the CAG trinucleotide repeat in the HTT gene on chromosome 4 (4p16.3), producing an abnormal huntingtin protein with an expanded polyglutamine tract. This misfolded protein disrupts cellular function, leading to neuronal death. Normal alleles have ≤26 repeats, 27–35 are intermediate (risk of expansion), 36–39 show reduced penetrance,...