Prenatal Screening for Tay-Sachs Disease by Louisiana Obstetricians: A Survey Study.

ABSTRACT

Background. Tay-Sachs disease has been reported to be more prevalent in the Cajun population of Louisiana.

Methods. Questionnaires were mailed to 744 obstetricians; 151 responded.

Results. Of the 151 responding physicians, 95 (63%) reported that they do not routinely screen their prenatal patients for Tay-Sachs disease. Of the 52 responding obstetricians in New Orleans, 29 (58%) offer screening; 8 of 23 obstetricians (32%) in Acadiana (southwest Louisiana) and 19 of 72 (27%) of the remaining Louisiana obstetricians routinely screen their patients. Of 46 obstetricians in practice less than 10 years, 22 (48%) offer screening; of 105 in practice longer, 35 (33%) offer screening. Of 100 obstetricians trained in Louisiana, 32 (32%) offer screening, compared with 25 of 51 (49%) of those trained elsewhere.

Conclusions. Most practicing obstetricians in Louisiana are not routinely offering Tay-Sachs screening to their prenatal patients. Screening may depend on location of practice, duration of practice, and place of training.

TAY-SAGHS DISEASE is the infantile form of cerebral sphingolipidosis, a progressive disorder marked by degeneration of brain parenchymal cells and the maculas. Eventually, this condition leads to dementia, blindness, paralysis, and death, usually by 2 to 3 years of age. It is inherited as an autosomal recessive trait. This condition arises from an error of lipid metabolism in which a defect in hexosaminidase A results in accumulation of ganglioside [GM.sub.2] in the brain. [1] Because Tay-Sachs disease is inherited in an autosomal recessive manner, certain ethnic groups are at higher risk for incidence of this condition. In Ashkenazi Jewish populations, the carrier rate may be as high as 1 in 30, as opposed to 1 in 300 in the general population. The carrier rate in French Canadian and Cajun populations has also been described as being as high as the Ashkenazi Jewish carrier rate. [2]

Preconception and prenatal testing can identify carriers of Tay-Sachs disease. Screening involves serum assay of hexosaminidase A.[3] In 1995, ACOG issued a committee opinion recommending screening for Tay-Sachs disease before pregnancy and prenatally if both members of a couple are Ashkenazi Jews or of French Canadian or Cajun descent.[4] Several authorities have followed in this recommendation.[5-8] Our study was designed to determine whether Louisiana obstetricians routinely offer screening for Tay-Sachs disease to their prenatal patients.

METHODS

A questionnaire survey (Appendix) was mailed to 744 obstetricians in the state of Louisiana in April 1999. This list of obstetricians was obtained from the Louisiana ACOG directory. A cover letter was prepared by the Woman's Foundation Inc, a nonprofit organization dedicated to women's health care education. The letter explained that the survey data would be used in a study to be submitted for publication. The survey itself asked if the physician offered screening, how screening was done, and how long screening had been done. It also asked if the physician had ever diagnosed Tay-Sachs disease prenatally, where the physician had completed training, and how long the physician had been in practice. Also included in the form was a blank for the physician to include a mailing address so that we could assess the location of the survey respondent.

RESULTS

Of 744 surveys mailed, 155 were returned. Four of the returned surveys were incomplete and were excluded, leaving a total of 151 surveys for use in the compilation of results. Only 37% of responding practitioners (95% confidence interval, 29%-44%) offer prenatal screening for Tay-Sachs disease (Table 1). According to these data, most obstetricians in Louisiana do not screen for Tay-Sachs disease (Student's paired t test, P= .0007).

Physicians practicing in the New Orleans area are more likely to offer screening than physicians practicing in other areas of the state (Student's paired t test, P= .004). Fifty-eight percent of physicians in New Orleans offer screening; 32% of physicians in Acadiana (the southwest Louisiana region with the largest Cajun population) routinely screen patients (Table 1).

Forty-eight percent of physicians in practice less than 10 years offer screening; 33% of physicians practicing more than 10 years offer screening (Table 2). Length of practice less than 20 years is associated with a more statistically significant likelihood of screening (Student's paired t test, P= .048). Thirty-two percent of physicians trained in Louisiana reported offering screening compared with 49% of physicians trained elsewhere (Table 3).

Of the 151 respondents, 4 (2.6%) reported having diagnosed Tay-Sachs disease prenatally. None of these patients were of French Canadian or Cajun descent; they were all Ashkenazi Jewish.

DISCUSSION

The majority of practicing obstetricians in Louisiana are not routinely offering screening for Tay-Sachs disease to their prenatal patients. Several factors seem to influence physicians' offering of screening.

A curious finding in this study is that in Acadiana (the region of south Louisiana traditionally associated with the largest Cajun population), relatively few obstetricians routinely screen for Tay-Sachs disease. Of the 32% of Acadiana physicians who reported routinely offering Tay-Sachs screening, none of them commented that they routinely offered screening to patients of Cajun or French Canadian descent. These physicians did report offering screening only to patients of Ashkenazi Jewish descent.

There are conflicting interpretations of these results. One interpretation suggests that obstetricians in Louisiana are not aware of the increased incidence of Tay-Sachs disease in Cajuns. Another interpretation suggests that there is no increased incidence of Tay-Sachs disease in Cajuns, and therefore practicing obstetricians in Louisiana do not believe that such screening is necessary or cost effective in the Cajun population.

There is no Tay-Sachs registry. This makes analysis of data more difficult, because there is no evidence of increased incidence of Tay-Sachs in our Cajun population in recent years. Even in discussions with pediatricians in our area, seeking anecdotal evidence of increased incidence of Tay-Sachs disease, there are no reported cases in recent years.

Supported in part by Woman's Foundation Inc, and Women's and Children's Hospital, Lafayette, La.

References

(1.) Robbins SL, Cotran R.S. Kurnar V: Pathologic Basis of Disease. Philadelphia, WB Saunders Go, 3rd Ed, 1984, pp 142-145

(2.) McDowell GA, Fabacher P, Shapiro F, et al: The presence of two different Tay-Sachs disease mutations in a Cajun population. Am J Hum Genet 1992; 51:1071-1077

(3.) Hogge JS, Hogge WA: Screening for genetic disorders; preconception genetic counseling. Clin Obstet Gynecol 1996; 39:758

(4.) ACOG Committee Opinion No. 162. Screening for Tay-Sachs disease. Washington DC, American College of Obstetricians and Gynecologists, 1995

(5.) Reece EA, Hobbins, JC, Mahoney MJ, et al: Medicine of the Fetus and Mother Philadelphia, JB Lippincott, 1992, pp 472-480

(6.) Cunniugham FG, McDonald PC, Gant N, et al: Prenatal diagnosis and invasive techniques to monitor the fetus. Williams Obstetrics. Stamford Conn, Appleton & Lange, 20th Ed, 1997, pp 919-920

(7.) Guidelines for Perinatal Care. Washington, DC, American Academy of Pediatrics and the American College of Obstetricians and Gynecologists, 1997, p 299

(8.) Niebyl JR, Simpson JL: Genetic counseling and prenatal diagnosis. Obstetrics; Normal and Problem Pregnancies. New York, Churchill-Livingstone, 1996, pp 222-223

TABLE 1

Survey Results According to Practice Location


                      Prenatal Screening for
                        Tay-Sachs Disease

                               Yes               No
                             (n = 56)         (n = 95)

Louisiana                      37%              63%
New Orleans (n = 52)           58%              42%
Acadiana (n = 23)              32%              68%
Other areas (n = 72)           27%              73%
TABLE 2

Survey Results Related to Length of Practice


                  Length of Time
                   in Practice

               [less than] 10 Years  [greater than] 10 Years
                     (n = 46)               (n = 105)

Do screen              48%                     33%
Do not screen          52%                     67%
TABLE 3

Survey Results Related to Training Location


               Training Location

                   Louisiana      Outside Louisiana
                   (n = 100)          (n = 51)

Do screen             32%                49%
Do not screen         68%                51%

KEY POINTS

* Tay-Sachs disease has been previously reported to be more prevalent in Loisiana's Cajun population.

* There is no evidence of abnormally high incidence, of TaySachs disease in Louisiana during the last decade.

* Most obstetricians in Louisiana do not routinely screen their prenatal patients for Tay-Sachs disease.