What We Offer

Enhanced Genetic Screening (EGS) Program

The enhanced genetic screening (EGS) program is often used as the framework in which many of our services are provided, though our services are also offered separately. What to expect in the EGS program:

• •The genetic counselor or physician obtains and analyzes a couple's family history, personal history, ethnic groups, medications, and other information, to determine if there are any risk factors for genetic abnormalities above the average 3% population risk of having a baby with a birth defect.



• •To identify carrier status for genetic disorders, blood-screening tests are offered as appropriate to the couple's ethnic group or groups. For example, for patients of Ashkenazi Jewish descent, there has been a continually increasing panel of disorders including well-known conditions such as Tay-Sachs diseases and many others just as common but less well known. Patients of African heritage are tested for sickle-cell anemia. Patients of Mediterranean origin are at high risk particularly for β-thalassemia. Patients of Asian descent are at high risk for α-thalassemia. Many other carrier screens are possible but not routinely performed because of low incidence and high expense, but they can be used when suggested because of family history.


• •To clarify the risks for Down syndrome and other genetic abnormalities, screening via first-trimester ultrasound, including nuchal translucency measurements, is performed in conjunction with blood tests.


• •For those patients found to be at risk sufficient for patient's concern, we perform prenatal diagnostic tests as indicated. Chorionic villus sampling (CVS) in the first trimester, and amniocentesis in the second, are used to determine chromosomal status, such as in Down syndrome. DNA tests are used for disorders such as cystic fibrosis, Tay-Sachs, or sickle-cell anemia.

Genetic Counseling

Our geneticists/genetic counselors obtain detailed family histories, analyze inheritance patterns, identify at-risk individuals, and help prospective parents to understand their particular genetic risks, options, and likely outcomes in pregnancy. Working with Dr Evans, the counselors explain the often complex world of new genetic tests and help patients make important decisions about their pregnancies.

Carrier Frequencies of Common Genetic Disorders

Cystic Fibrosis is perhaps the best known Mendellian disorder in the European population. Its incidence and the component markers vary considerably by ethnic group.

The "Ashkenazi Jewish Panel"

Recent advances in genetics have led to the expansion of carrier screening for individuals of Ashkenazi Jewish ancestry. For decades screening was available only for Tay-Sachs disease. With advanced capabilities over the past decade, screening is now available for up to 17 conditions. The conditions include:

TAY SACHS DISEASE: The "classic" Ashkenazi Jewish disorder which is characterized by normal development until about 4 -6 months of age followed by progressive neurodegenerative findings including blindness, seizures, and unresponsiveness. Death is common by age 4.

CANAVAN'S DISEASE: Normal development up until age 2 – 4 months followed by progressive degeneration, seizures, and blindness. Lifespan can vary from early childhood into early teens.

CYSTIC FIBROSIS: Inability to transport chloride across cellular membranes leads to thick mucus in lungs and GI tract resulting in multiple infections. Lifespan has extended dramatically in the past 25 years to now average near 40.

FAMILIAL DYSAUTONOMIA: Abnormalities of autonomic and sensory nervous system affect control of body temperature, blood pressure, stress, and sensitivity to pain. Poor growth is common and lifespan is limited. SPINAL MUSCULAR ATROPHY: Degenerative nervous disorder with progressive downill course. Death is common by age 2.

FANCONI ANEMIA TYPE C: Short stature, bone marrow failure and a predisposition to leukemia and cancers. Shortened lifespan

GAUCHER DISEASE Type 1: Variable presentation including spleen enlargement, anemia, fatigue, bruising, and bone deterioration.

GLYCOGEN STORAGE DISEASE TYPE 1a: Metabolic disorder characterized by hypoglycemia (sudden drops in blood sugar levels), poor growth, enlarged liver, and anemia.

MAPLE SYRUP URINE DISEASE: Abnormality of protein metabolism. Untreated symptoms include poor feeding, lethargy, seizures, and coma.

BLOOM SYNDROME: Short stature, skin rash, chromosomal breakage, infections, and high incidence of leukemia.

DIHYDROLIPOAMIDE DEHYDROGENASE DEFICIENCY: Metabolic disorder resulting in blindness, seizures, enlarged liver, blindness, and short lifespan.

FAMILIAL HYPERINSULINISM: Low levels of blood sugar resulting in seizures, poor muscle tone, sleep disorders, and poor feeding.

MUCOLIPIDOSIS IV: Progressive neurological disorder leading to muscle weakness, impaired intellect, limited vision, and shortened lifespan.

NEMALINE MYOPATHY: Low muscle tone, poor breast feeding and problems breathing. Delayed development.

USHER SYNDROME 1F: Profound hearing loss and adolescent onset of retinitis pigmentosa with severely impaired vision.

USHER SYNDROME III: Progressive hearing and vision loss. Blindness by adulthood.

JOUBERT SYNDROME: Brain abnormality produces poor muscle tone, rapid breathing, abnormal eye movements, developmental delay, and poor gait.

Many of these disorders are very rare and many are just as common in other ethnic groups. As many of these tests are expensive and rare, the decision to screen for them has to be individualized. The carrier frequencies and detection rates of these conditions are listed in the following tables.

Fragile X Syndrome

Fragile X is a leading cause of male mental retardation occurring in about 1/4000 overall but some populations are higher. It is an X- linked dominant disorder which means that the full manifestations of the syndrome are seen in males who inherit the gene from their mothers. Its inheritance is also "imprinted" meaning that it matters from which parent the gene came - in this case the mother. The disease is related to the number of "repeats" of a tri-nucleotide of DNA base pairs - in this case the DNA nucleotides "CGG" at the end of the FMR1 gene on the X chromosome. Classically 200 such repeats are needed for the disease, and most normal women have about 30 repeats on each of their X chromosomes. As the number of repeats goes up, infertility increases as does the likelihood of expansion of the number of repeats up to problem levels. Women who carry the gene may have some minor manifestations, but these are commonly unnoticed. In recent years, however, there has been an emerging appreciation of partial effects of Fragile X even with less than the usually required number of repeats needed for the full diagnosis.

Spinal Muscular Atrophy

Spinal Muscular Atrophy (SMA), which in older literature was known as Werdnig-Hoffman Disease, is a rare cause of a lethal disorder with an incidence of about 1 in 4000. It is autosomal recessive meaning that both parents need to be carriers, and the age of the parents is irrelevant. Carrier testing for SMA has recently become available but is not yet universally accepted as routine.