Related Experiment Videos
[Lynch syndrome I: a case report]
Vesna Zivković1, Vuka Katić, Jasmina Gligorijević
1Institut za patologiju, Medicinski fakultet Nis.
Medicinski Pregled
|September 19, 2008
Summary
Hereditary nonpolyposis colorectal cancer (HNPCC), or Lynch syndrome, is linked to DNA mismatch repair gene mutations. Early colonoscopic screening for at-risk families is recommended due to genetic testing limitations.
Area of Science:
- Oncology
- Genetics
- Gastroenterology
Background:
- Hereditary nonpolyposis colorectal cancer (HNPCC), also known as Lynch syndrome, accounts for 5-8% of colorectal cancers.
- Lynch syndrome I is an autosomal dominant disorder with early-onset colorectal cancer, proximal and multiple tumors, and microsatellite instability.
- The Amsterdam criteria are used for HNPCC identification.
Observation:
- A 40-year-old male presented with advanced rectal cancer (Dukes C).
- His family history revealed five members with colorectal cancer across two generations, diagnosed before age 45.
- One member had metachronous transverse cancer 12 years after surgery for cecal adenocarcinoma.
Findings:
- The patient met the Amsterdam criteria for Lynch syndrome I.
- HNPCC is primarily caused by mutations in mismatch repair (MMR) genes (MLH1, MSH2), leading to microsatellite instability in 90-95% of cases.
Implications:
- Family members meeting Amsterdam criteria require investigation for MMR gene mutations.
- Genetic testing is not widely available, necessitating colonoscopic screening for asymptomatic relatives over 25.
- Early detection and surveillance are crucial for managing Lynch syndrome.
Related Concept Videos
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...
02:41Lethal Alleles
Agouti: A Lethal Allele
Lucien Cuénot discovered lethal alleles in 1905 while studying the inheritance of coat color in mice. The agouti gene is responsible for the color of the coat in mice. This gene codes for an agouti-signaling protein, which is responsible for melanin distribution in mammals. The wild-type allele gives rise to gray-brown coat color in mice, while the mutant allele gives rise to yellow coat color. In addition to coat color, the agouti gene is associated with the yellow...
Lucien Cuénot discovered lethal alleles in 1905 while studying the inheritance of coat color in mice. The agouti gene is responsible for the color of the coat in mice. This gene codes for an agouti-signaling protein, which is responsible for melanin distribution in mammals. The wild-type allele gives rise to gray-brown coat color in mice, while the mutant allele gives rise to yellow coat color. In addition to coat color, the agouti gene is associated with the yellow...
01:43Sex Linked Disorders
Like autosomes, sex chromosomes contain a variety of genes necessary for normal body function. When a mutation in one of these genes results in biological deficits, the disorder is considered sex-linked.