Differences in laboratory reporting standards leading to a difficult prenatal diagnosis for a patient with suspected 4p duplication.

Not all obstetric care facilities offer sufficient genetic counseling in Japan. When necessary, patients are referred to tertiary perinatal care centers for genetic counseling and further testing. Because each facility typically has an exclusive contract with a laboratory, the additional testing required may be performed at a different laboratory. With no reporting standards for normal chromosomal variants, differences between laboratories impede result interpretation, and clinical errors may occur. We present a case of a patient diagnosed with 46,XX,?dup (4)(p12p12) variant over two pregnancies. During the first pregnancy, the variant was determined to be a de novo, leading the parents to terminate the pregnancy. During the second pregnancy, further analysis revealed no 4p duplication, and we diagnosed as a normal variant, 4cenh+, inherited from the mother. Differences in reporting standards for a normal variant made evaluation of this patient difficult. Medical staff should be aware of this issue, and reporting standards should be standardized.