Prenatal diagnosis of mucopolysaccharidoses (MPS): the first Egyptian experience

Prenatal diagnosis of mucopolysaccharidoses (MPS) in pregnant females with previously affected child or more.

Prospective clinical study.

The present study included 14 pregnant females with previously affected child or more with one of the MPS types. These were 5 type I (Hurler), 3 type II (Hunter), 3 type III (Sanfilippo), 1 type IV (Morquio) and 2 type VI (Maroteaux-Lamy). Eleven patients came from Cairo metropolitan area (Cairo, Giza and Kaluobia governorates). Consanguinous marriage was present in 11 (78.6%) couples. Six families have no normal children and eight families have normal children, 5 have girls and 3 have boys. The gestational age at the time of their first visit was 13 weeks or less in 9 cases and more than 13 weeks in 5 cases. All the pregnant females were subjected to history taking, pedigree construction, clinical examination and ultrasound scan. Proper counseling was done and patients were scheduled for prenatal diagnosis. One case (type II) did not come in scheduled time.

Amniocentesis was done at the 15th week gestational age in 10 cases to withdraw 10 ml of amniotic fluid for the analysis of the glycosaminoglycans (GAG) by the two-dimensional electrophoresis (2-DEP). Chorionic villus sampling (CVS) was done at 11-12 weeks gestational age in 3 cases (type I, type III B and type IV A) to perform the specific enzyme assay fluorimetrically which was developed during the study.

10 cases were proved to be normal fetuses. Three were diagnosed as affected MPS fetuses. The first as MPS II by amniocentesis, the second as MPS type III by amniocentesis and the third as MPS III B by CVS.

Couples, with an affected MPS child, are eager to have a normal child. So, they are keen to do prenatal diagnosis. Prenatal diagnosis of MPS by the analysis of the glucosaminoglycans (GAG) using the two-dimensional electrophoresis of amniotic fluid is a sensitive and accurate method. However, prenatal diagnosis by the fluorimetric assay of the relevant enzyme in chorionic villi is recommended as CVS is done 3-4 weeks earlier than amniocentesis, so it will offer an earlier diagnosis which is more favourable medically and ethically. During the course of the study, we established the enzymatic diagnosis for types I, III B and IVA. Now the enzymatic diagnosis is available for all types of MPS. (Tab. 1, Ref. 15.)