A pair of unrelated 4-year-olds (Lester and Lucy) have mucopolysaccharidosis 1 (MPS1). Lester has severe dysmorphic features and many skeletal anomalies. Lucyhas onlymildly coarse features and slight developmental delay. What is the best explanation for these differences?
A)Skewed X inactivation allowed more paternal X expression for Lucy and more maternal X expression for Lester.
B)Lucy's mother had better prenatal care, including good diet, exercise, and vitamins, than Lester's mother.
C)It is likely that Lucy has been misdiagnosed and really has MPS2.
D)The disorder has wide variability in expression of severity.

Question

Quizplus · Accepted Answer

There are over 100 different mutations in the gene that can cause Hurler syndrome (MPSI). This is responsible for the wide variations in disease severity. MPS1 is an autosomal-recessive disease, and prenatal care does not appear to have an impact on disease severity. Because the gene is not on the X chromosome, skewed X inactivation is not a plausible explanation for the difference in severity. Clinical testing for MPS1 and MPS2 is accurate. Misdiagnosis is not likely.

A Pair of Unrelated 4-Year-Olds (Lester and Lucy) Have Mucopolysaccharidosis