Neu-Laxova Syndrome Health Article

Diagnosis

Many infants with NLS have been born into families with no previous history of the disorder and/or ones in which the parents are unrelated. Thus, an exact diagnosis of NLS during pregnancy may be very difficult, particularly for a couple with no apparent risk factors. Direct genetic testing for NLS will not be possible until the responsible gene has been identified. Some non-specific prenatal findings should, however, alert the physician that additional prenatal evaluation is warranted. These include IUGR and polyhydramnios. Both findings often lead to an obvious difference in the size of a pregnant woman's uterus and her estimated weeks of pregnancy. A woman whose fetus has severe IUGR and normal amniotic fluid often appears less pregnant than she actually is. In contrast, a woman with polyhydramnios often appears more pregnant, or larger. A detailed prenatal ultrasound test may be used to obtain pictures of abnormalities of the fetus as well as possible abnormalities of the placenta whenever there is an apparent discrepancy in a woman's size and her dates.

Two groups have separately reported diagnosis of NLS using ultrasound. However, in both cases, the diagnosis was formally established only after delivery. A number of the physical findings associated with NLS, particularly those involving the face, limbs, and brain, may be apparent following a detailed ultrasound later in pregnancy. In experienced hands and with the knowledge of a previous affected infant, some of these findings may be observed earlier.

In one of the published cases, a diagnosis of NLS was helped by the physical findings of an ultrasound exam at 32 weeks of pregnancy. The fetus was found to have many of the abnormalities associated with NLS. In the second report, ultrasound was used to assess fetal movement patterns at 34 weeks of pregnancy. Abnormal fetal movement is indicative of abnormal brain development. The authors were able to document a lack of normal fetal activity, such as breathing movements, sucking, swallowing, hiccups, and movements of the arms and legs in a fetus diagnosed with NLS after birth.

Accurate diagnosis of this condition is difficult before birth for those couples in which no NLS gene has been identified and no family history of NLS is known. While the combination of abnormal physical development and possibly abnormal fetal activity is highly indicative of a severe genetic condition, both would not be specific enough to pinpoint Neu-Laxova syndrome as the cause in all cases. Other genetic syndromes would be under consideration, pending a clinical examination after delivery.

For this reason, a careful physical evaluation after birth is critical in establishing a diagnosis of NLS. For those infants who are stillborn and for those who die after delivery, an autopsy is also helpful in documenting all of the associated internal abnormalities. A precise diagnosis facilitates accurate genetic counseling, including prognosis for an affected child and the risk of recurrence for future pregnancies.

Treatment and management

For those couples who have had a previous child with Neu-Laxova syndrome, serial prenatal ultrasound evaluations should be offered to monitor fetal growth, screen for physical abnormalities, and, assess fetal well-being later in pregnancy given the increased risk for stillbirth. Ultrasound diagnosis of any of the structural birth defects associated with NLS in these families should be considered evidence of the disorder. Since some of these findings may not become evident until later in pregnancy, termination of the pregnancy may not be an option for some couples. Plans for the remainder of the pregnancy as well as delivery can, however, be discussed. Given the serious prognosis associated with NLS, some parents may find a noninterventionist approach during labor and delivery, such as no fetal monitoring or Cesarean section delivery, acceptable. A clinical examination after birth is recommended.

Most infants with NLS have either been stillborn or died very shortly after delivery. However, there is one reported case of an affected Japanese infant who lived for 134 days. Humane medical care is therefore appropriate in survivors although the prognosis would still be extremely poor.

An autopsy is recommended on all affected infants after death to document and confirm all of the associated physical abnormalities. While this acts as a way to confirm the diagnosis, it is also a useful way to continue to add to the knowledge about the syndrome and its physical effects.

Prognosis

The number of infants described with Neu-Laxova syndrome is small. However, with the exception of the reported infant who lived 134 days, all affected children have either died before delivery or shortly thereafter. Neu-Laxova syndrome is a serious genetic condition whose anomalies prevent long-term survival.

BOOKS

Jones, K. L., ed. "Neu-Laxova syndrome." In Smith's Recognizable Pattern of Human Malformations. W. B. Saunders Company, Philadelphia, 1997.