A newborn with shortened palpebral fissures and microcephaly is most likely diagnosed with which condition?

The presence of shortened palpebral fissures and microcephaly is highly indicative of fetal alcohol syndrome (FAS). This condition occurs when a mother consumes alcohol during pregnancy, leading to a range of physical, behavioral, and cognitive problems in the offspring. The characteristic facial features associated with FAS include the shortened palpebral fissures, smooth philtrum, and thin upper lip, alongside potentially significant neurological effects like microcephaly, which is a reduction in head size that can reflect underlying brain development issues.

The other conditions listed do not specifically present with both of these features. For instance, Down syndrome may show variations in head shape and size, but it is not characterized by shortened palpebral fissures in the same manner as FAS. Growth retardation refers to inadequate growth typically in relation to weight or height, rather than specific dysmorphic features. Hydrocephalus primarily involves an enlargement of the head due to increased cerebrospinal fluid, which can sometimes be confused with microcephaly but does not characteristically include the same palpebral fissure changes seen in fetal alcohol syndrome. Thus, the combination of shortened palpebral fissures and microcephaly aligns closely with the diagnosis of fetal alcohol syndrome