Hypohidrotic ectodermal dysplasia (HED) is a very rare disease characterized by the virtual absence of eccrine glands, dry skin, scanty hair, and dental abnormalities. It is transmitted by an X-linked recessive gene or rarely an autosomal recessive gene. Therefore it is only males who fully express the condition. It is caused by mutations within the ED1 gene, which encodes a protein, ectodysplasin-A (EDA). Typically there is frontal bossing, saddle nose, pointed chin, a prominent supraorbital ridge with periorbital hyperpigmentation, and absence of teeth. Those affected show great intolerance to heat. In the current absence of effective treatment for many hereditary skin diseases, comprehensive, accurate prenatal or postnatal genetic counseling can provide information to parents at risk of having affected children. We report HED in a 6-year-old boy with an Ala349Thr (GCA --> ACA) missense mutation developed de novo. Both parents and a 16-week gestational age fetus were healthy. We thought direct sequencing analysis for the ED1 gene using peripheral blood or amniotic fluid was preferable for an accurate diagnosis of this disease, although there was some risk of not detecting the mutation. After the results of this study were communicated to the parents, the mother was freed of her guilty feelings of the past 6 years and has now delivered a healthy male infant.