Which of the following is not a single gene disorder?
Ans: C (MVP) Ref: Robbins Pathologic Basis of Disease, 8th edition, pg: 1304 Explanation:Single Gene DisorderDue to a single mutated gene.They usually follow Mendelian Principle of Inheritance.Autosomal Dominant and recessive.X linked dominant and recessive.Y linked.Mitochondrial inheritance."In 20% to 50% of cases, DCM is familial and caused by inherited genetic abnormalities. In the genetic forms of DCM, autosomal- dominant inheritance is the predominant pattern; X-linked, autosomal-recessive, and mitochondrial inheritance are less common. The genetic abnormalities identified as causes of familial DCM in humans most commonly affect genes that encode cytoskeietal proteins expressed by myocyte. " Ref: Robbins"Arrhythmogenic right ventricular cardiomyopathy (ARVC), or arrhythmogenic right ventricular dysplasia is an autosomal dominantly inherited disease of the cardiac muscle that causes right ventricular failure and various rhythm disturbances, particularly ventricular tachycardia or fibrillation that can lead to sudden death. primarily in young people Left-sided involvement with left-sided heart failure may also occur Morphologically, the right ventricular wall .is severely thinned because of loss of myocytes, with extensive fatty infiltration and fibrosis. The condition appears to have autosomal- dominant inheritance and variable penetrance The disease seems to be related to defective cell adhesion proteins in the desmosomes that link adjacent cardiac myocytes." Ref: Robbins"HOCM is caused by mutations in any one of several genes that encode sarcomeric proteins. In most cases the pattern of transmission is autosomal dominant with variable penetrance Remaining cases seem to be sporadic. More than 400 different mutations have been found in nine different genes in HCM, most being missense mutations. Mutations causing HOCM are found most commonly in the gene encoding b-myosin heavy chain (b-MHC), with the genes for cardiac TnT, a-tropomyosin. and myosin-binding protein C (MYBP- C) being the next most frequently mutated. Mutations in b-MHC, MYBP- C, and TnT account for 70% to 80% of all cases of HOCM." Ref: Robbins"The basis for the changes that weaken the valve leaflets and associated structures is unknown in most cases. Uncommonly, MVP Is associated with heritable disorders of connective tissue including Marfan syndrome, which is usually caused by mutations in fibril!in-1 (FBN-1)." Ref: RobbinsDiseasePredominant Inheritant PatternHOCMAutosomal DominantDCMAutosomal DominantArrhythmogenic right ventricular dysplasiaAutosomal Dominant
HOCM
DCM
MVP
Arrhythmogenic right ventricular dysplasia
Mendelian Disorders: Single-Gene Defects