Increased nuchal translucency in a case of long-chain 3-hydroxyacyl- coenzyme A dehydrogenase deficiency

Lysosomal storage disorder in non-immunological hydrops fetalis (NIHF): more common than assumed? Report of four cases with transient NIHF and a review of the literature

Background

Lysosomal storage disorders (LSD) are a rare cause of non immunological hydrops fetalis (NIHF) and congenital ascites. The reported incidence is about 1%. The incidence of idiopathic NIHF is estimated to be about 18%.

Patients and methods

We report four cases with transient hydrops fetalis resulting from LSD and performed a literature review on LSD with NIHF and congenital ascites in combination.

Results

At present, 12 different LSDs are described to be associated with NIHF or congenital ascites. Most patients had a family history of NIHF, where the preceding sibling had not been examined. A diagnostic approach to the fetus with NIHF due to suspected LSD either in utero or postnatal is suggested. Transient forms of NIHF and/or ascites in association with MPS IVA, MPS VII and NPC are described for the first time in this publication.

Conclusions

LSD should be considered in transient hydrops. Enzymatic studies in chorionic villous sample or amniotic cultured cells, once the most common conditions associated with fetal ascites or hydrops have been ruled out, are important. This paper emphasizes the fact that LSD is significantly higher than the estimated 1% in previous studies, which is important for genetic counseling as there is a high risk of recurrence and the availability of enzyme replacement therapy for an increasing number of LSD.

Lysosomal storage diseases in non-immune hydrops fetalis pregnancies

BACKGROUND

At least 20 inborn errors of metabolism may cause hydrops fetalis. Most of these are lysosomal storage diseases. The study proposes a diagnostic flowchart for prenatal diagnosis of non-immune hydrops fetalis.

METHODS

This study contains a series of 75 non-immune hydrops fetalis pregnancies. Mucopolysaccharides, oligosaccharides, neuraminic acid and 21 lysosomal enzymes were measured in amniotic fluid and cultured amniotic cells.

RESULTS

The study gives reference values for mucopolysaccharides and neuraminic acid at various stages of gestation. Four definite and two probable lysosomal diagnoses were found among the 75 investigated cases (=5.3-8%). Fetal death was found to cause false positive values for mucopolysaccharides in amniotic fluid. In the galactosialidosis case, two novel mutations were found in the cathepsin A gene.

CONCLUSIONS

Reference values for mucopolysaccharides and neuraminic acid depend on gestational age. In a relatively high percentage of the hydrops foetalis pregnancies, a lysosomal aetiology is found. This study provides a strategy to diagnose lysosomal diseases in hydrops fetalis pregnancies. Awareness of lysosomal storage diseases causing hydrops fetalis is useful as it gives an opportunity for risk evaluation, genetic counseling to parents and targeted prenatal diagnostics for ensuing pregnancies.

Increased nuchal translucency with normal karyotype

Increased fetal nuchal translucency (NT) thickness between 11 and 14 weeks' gestation is a common phenotypic expression of chromosomal abnormalities, including trisomy 21. However, even in the absence of aneuploidy, nuchal thickening is clinically relevant because it is associated with an increase in adverse perinatal outcome caused by a variety of fetal malformations, dysplasias, deformations, dysruptions, and genetic syndromes. Once the presence of aneuploidy is ruled out, the risk of perinatal outcome dose not statistically increase until the nuchal translucency measurement reaches 3.5 mm or more (>99th percentile). This increase in risk occurs in an exponential fashion as the NT measurement increases. However, if the fetus survives until midgestation, and if a targeted ultrasound at 20 to 22 weeks fails to reveal any abnormalities, the risk of an adverse perinatal outcome and postnatal developmental delay is not statistically increased.

First-trimester fetal nuchal translucency and inherited metabolic disorders

OBJECTIVES

To assess the association between inherited metabolic disorders and nuchal translucency (NT) measurements.

METHODS

The NT measurements obtained from 66 fetuses at high risk for metabolic diseases prior to chorionic villus sampling (CVS) were retrospectively analysed.

RESULTS

NT was found to be within the normal range in all of the 13 affected fetuses, which included three with Gaucher disease, two with glycogenosis type II, two with mucopolysaccharidosis type I and six others with Krabbe disease, metachromatic leukodystrophy, mucopolysaccharidosis type II, Niemann-Pick A disease, Pelizaeus-Merzbacher disease and sialidosis, respectively. An increased nuchal thickness was found only in one fetus affected with trisomy 21 but not affected with mucopolysaccharidosis type II.

CONCLUSION

NT appears to have a limited role in identifying affected fetuses in pregnancies at high risk for inherited metabolic disorders. NT may be normal in early pregnancy even for fetuses affected with conditions known to be associated with non-immune hydrops fetalis.

Outcome of pregnancy in chromosomally normal fetuses with increased nuchal translucency in the first trimester

OBJECTIVES

To study the outcome of chromosomally normal pregnancies with increased nuchal translucency at the 10-14-week scan.

DESIGN

Retrospective study of 1320 chromosomally normal singleton pregnancies with nuchal translucency of > or = 3.5 mm. In addition to fetal karyotyping these patients were managed with follow-up scans at 14-16 and 20-22 weeks, specialist fetal echocardiography and in selected cases by infection screening and further genetic testing.

RESULTS

In the 1320 pregnancies there were 68 (5.15%) spontaneous abortions or intrauterine deaths, 18 (1.36%) neonatal and infant deaths and 154 (11.67%) terminations of pregnancy. In the 1080 (81.82%) survivors, 60 (5.56%) had abnormalities requiring medical or surgical treatment or leading to mental handicap. The chance of a livebirth with no defects in the group with nuchal translucency of 3.5-4.4 mm was 86%, for those with translucency of 4.5-5.4 mm it was 77%, for those with translucency of 5.5-6.4 mm it was 67%, and for those with translucency of > or = 6.5 mm it was 31%.

CONCLUSIONS

Increased fetal nuchal translucency is associated with chromosomal abnormalities, many fetal defects and genetic syndromes. In the majority of cases a series of antenatal investigations, including fetal karyotyping, detailed scans, fetal echocardiography, as well as genetic testing and infection screening, that can be completed by 20 weeks of gestation would distinguish between the pregnancies destined to result in adverse outcome and those leading to the delivery of infants without major defects.