American Medical Association Family Medical Guide - American Medical Association [667]
Symptoms
The overproduction of male sex hormones can cause newborn girls to have ambiguous genitalia. The clitoris enlarges to the size of a small penis, and the external lips of the vagina may fuse to look like a scrotum. Newborn boys may look normal at birth but, without treatment, they display very early signs of puberty, sometimes as young as 2 or 3 years of age. Their penis enlarges, their voice deepens, pubic hair appears, and their body becomes muscular.
A deficiency in aldosterone can cause a severe loss of salt from an infant’s body, resulting in dehydration, vomiting, and an abnormal heartbeat. This life-threatening condition occurs during the first few days or weeks after birth. If your child is vomiting and is severely dehydrated, take him or her to a hospital emergency department immediately for treatment. The signs of dehydration include pale, dry skin that looks loose; dry lips and tongue; a lack of tears; a decrease in urine output (fewer wet diapers in infants); and a sunken soft spot on the skull (if still present in a child). Other signs of dehydration include a rapid heartbeat, sunken eyes, lack of energy, and, in severe cases, behavior changes.
Diagnosis
Many states require a newborn screening test for the most common missing enzyme in congenital adrenal hyperplasia; for this reason, many affected children are diagnosed and treated early, before symptoms appear. In a child who has not been tested, a doctor can diagnose the disorder from the symptoms and the results of blood, urine, and hormone tests. He or she may also do an ultrasound scan of the child’s adrenal glands.
Treatment
Children who have congenital adrenal hyperplasia are given drugs to replace the deficient hormones, returning their hormone levels to normal and decreasing their body’s production of androgens. They continue taking the hormones for life. Baby girls with ambiguous genitalia need to have surgery to correct the appearance of their external reproductive organs. This reconstructive surgery is usually done between ages 1 and 3. With early treatment, a child will have normal sexual development and function, including normal fertility.
Tay-Sachs Disease
Tay-Sachs disease is a rare, devastating inborn error of metabolism caused by the lack of an enzyme called hexosaminidase A, which helps break down fats in brain and nerve cells. Without the enzyme, fats build up and destroy the central nervous system, causing paralysis and early death, usually by age 4 or 5. The disorder is most common among Ashkenazi Jews. Because the genetic defect is recessive, a child is affected only if both parents are carriers of the gene and the child inherits a copy of the gene from each parent.
All Ashkenazi Jewish couples are offered genetic testing to determine if they are carriers of the gene—nearly 1 in 29 Ashkenazi Jews is a carrier of the Tay-Sachs gene. If both parents are found to be carriers of the gene, they can have prenatal testing (see page 954) to determine if the fetus is affected. A genetic counselor can help them evaluate their risk of having a child with Tay-Sachs disease and can explain various family planning options they may want to consider.
Symptoms
Most newborns with Tay-Sachs disease appear normal at birth but begin losing muscle strength at about 3 to 6 months of age. They have difficulty turning over or sitting up, they stop smiling, they lose interest in their surroundings, and they have delayed mental and physical development. They may have seizures and severe constipation, and they gradually become blind, deaf, and paralyzed.
In a rare form of the disease, the symptoms don’t appear until ages 2 to 5, and the disease progresses more slowly, but usually causes death by age 15.
Diagnosis
Tay-Sachs disease can be diagnosed before birth using chorionic villus sampling, or CVS (see page 511), or amniocentesis (see page 510). After birth, the disease can be diagnosed by a blood test that measures the level of the enzyme hexosaminidase A.
Treatment
Tay-Sachs disease has no treatment.