This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Unknown
[{'content': 'True statement among regarding autosomal dominant disorder: \nSelect and explain. \nA. Present early in life, B. Complete penetrance common, C. New germ cell mutations in old fathers, D. Only one generation involved', 'role': 'user'}, {'content': 'Answer: C \nExplanation: (Refer: Robbins Pathologic Basis of Disease, 8thedition, pg no: 140-141)\nAutosomal dominant inheritance pattern\n\nSuccessive or multiple generations of family are affected.\nOne faulty copy of gene (i.e. mutant allele) in any autosomeand one copy of normal allele.\nDisease phenotype is seen in all such individuals.\nPatients having disease have 50% chance of passing on thedisease to the next generation.\nBoth males and females are affected equally.\nBoth males and females can transmit the condition to progeny\nThere is atleast one instance of male to male transmission.\nDisease manifests in heterozygous state, so at least oneparent of an index case is usually affected.\nWhen an affected person marries an unaffected one, every child has one chance in two of having the disease.\nClinical features can be modified by variations in penetranceand expressivity.\nSome individuals inherit the mutant gene but are phenotypicallynormal. This is referred to as incomplete penetrance\nPenetrance is expressed in mathematical terms. Thus, 50%penetrance indicates that 50% of those who carry the geneexpress the trait.\nIn practice, penetrance risk is less than 10%.\nIf a trait is seen in all individuals carrying the mutant gene but isexpressed differently among individuals, the phenomenon iscalled variable expressivity. For example, manifestations ofneurofibromatosis type 1 range from brownish spots on the skinto multiple skin tumors and skeletal deformities.\nIn many conditions the age at onset is delayed.\nSymptoms and signs may not appear until adulthood (as inHuntington disease).\nMany autosomal dominant diseases (e.g. achondroplasia) havebeen shown to be associated with increasing paternal age,\nPaternal age is an important determinant in new germ cellmutation, causing both autosomal dominant and X-linkedrecessive illnesses.\nTypes of mutation', 'role': 'assistant'}]