Radiographic techniques are generally used only postnatally and also rely on prototypical physical characteristics. Nutrition has been shown to affect intelligence prenatally and postnatally. Furthermore, transmission can also occur postnatally or prenatally within parent-progeny relationships. However, it is more noticeably expressed postnatally. The gene has been show to play a role in the heart's conduction system, postnatally. Also, much better medical testing is available, both prenatally and postnatally. Turner syndrome can be diagnosed postnatally at any age. However, these mice are smaller than the wild type both neo and postnatally. Normally, Ccna2 is silenced postnatally in mammalian cardiac myocytes. Postnatally, the mammary ducts elongate into the mammary fat pad. Although present at birth, some only become obvious postnatally. KCC2 knockout animals, in which KCC2 is completely absent, die postnatally due to respiratory failure. Gabrb3 shows significantly reduced expression postnatally, when mice are deficient in MECP2. Postnatally, OPCs remain lineage-restricted and generally only differentiate into oligodendrocytes. Fertilization age is sometimes used postnatally (after birth) as well to estimate various risk factors.