]> 2026-07-31T11:51:03+00:00 WBR0436 0 en Variable expression Incomplete penetrance Locus heterogeneity Locus heterogeneity is defined as mutations at different locations that result in the same phenotype. Heteroplasmy Heteroplasmy is the presence of more than one mitochondrial DNA type, resulting in variable expression of a mitochondrial inherited disease. Imprinting Imprinting is the situation when a phenotype is dependent on whether a particular gene is or is not methylated. For example, Prader-Willi and Angelman’s syndromes are both mutations of the same region in chromosome 15; but the disease is caused by a mutation derived paternally in Prader-Willi, whereas it is derived maternally in Angelman’s syndrome. Genetics A 2-month-old boy is brought the pediatrician’s office for a history of multiple fractures with minor trauma. Work-up reveals the patient has osteogenesis imperfecta. The pediatrician explains to the family that the disease is most commonly inherited in an autosomal dominant pattern. Genetic analysis of both parents reveals that the child’s mother has a genotype similar to that of her son, but is not affected by the disease. Which of the following genetic characteristics best explains this finding? B Reproductive 2020-10-28T00:33:46Z 2459150.5234491 WBR0436