Early ultrasonographic diagnosis of diastrophic dysplasia at 12 weeks of gestation in a fetus without previous family history

Prenatal diagnosis of diastrophic dysplasia in the second trimester of pregnancy: Two- and three- dimensional ultrasonographic findings

To present a prenatal diagnosis of diastrophic dysplasia in the second trimester of pregnancy using two- (2D) and three-dimensional (3D) ultrasonography. The mother was primigravida and aged 12 years. She underwent the first 2D obstetric ultrasound examination at 27 weeks, showing bilaterally upper and lower limb micromelia, thumb and hallux in bilateral abduction, bilateral talipes equinovarus; hyperlordosis of the lumbar spine, cervical, lumbar, and sacral scoliosis; cervical hyperkyphosis with the misalignment of cervical vertebrae, and straight clavicles. 3D ultrasonography in conventional and HDlive rendering modes confirmed the changes observed in 2D ultrasonography and allowed improved understanding by the parents. At birth, the newborn presented transient respiratory distress and neonatal sepsis. At the time of writing, the child is aged 31 months and under follow-up by the pediatrics department. 3D ultrasound allowed the parents to understand the fetal malformations better, and they received adequate counseling.

N-acetylcysteine treatment ameliorates the skeletal phenotype of a mouse model of diastrophic dysplasia

Diastrophic dysplasia (DTD) is a recessive chondrodysplasia caused by mutations in SLC26A2, a cell membrane sulfate-chloride antiporter. Sulfate uptake impairment results in low cytosolic sulfate, leading to cartilage proteoglycan (PG) undersulfation. In this work, we used the dtd mouse model to study the role of N-acetyl-l-cysteine (NAC), a well-known drug with antioxidant properties, as an intracellular sulfate source for macromolecular sulfation. Because of the important pre-natal phase of skeletal development and growth, we administered 30 g/l NAC in the drinking water to pregnant mice to explore a possible transplacental effect on the fetuses. When cartilage PG sulfation was evaluated by high-performance liquid chromatography disaccharide analysis in dtd newborn mice, a marked increase in PG sulfation was observed in newborns from NAC-treated pregnancies when compared with the placebo group. Morphometric studies of the femur, tibia and ilium after skeletal staining with alcian blue and alizarin red indicated a partial rescue of abnormal bone morphology in dtd newborns from treated females, compared with pups from untreated females. The beneficial effect of increased macromolecular sulfation was confirmed by chondrocyte proliferation studies in cryosections of the tibial epiphysis by proliferating cell nuclear antigen immunohistochemistry: the percentage of proliferating cells, significantly reduced in the placebo group, reached normal values in dtd newborns from NAC-treated females. In conclusion, NAC is a useful source of sulfate for macromolecular sulfation in vivo when extracellular sulfate supply is reduced, confirming the potential of therapeutic approaches with thiol compounds to improve skeletal deformity and short stature in human DTD and related disorders.

First trimester three-dimensional ultrasonographic diagnosis of diastrophic dysplasia: a case report and review of the literature

Diastrophic dysplasia is a rare genetic disorder characterized by short limbs and deformities of several joints occurring in conjunction with xyphoscoliosis, distinctive abduction of the first metacarpals (hitchhiker thumbs). A 28-year-old pregnant patient was referred due to detection of increased nuchal translucency at the first-trimester scan. We describe a case of diastrophic dysplasia diagnosed by two- and three-dimensional ultrasound and termination of pregnancy at 13 weeks of gestation. This case is the first report in the literature in which 3D ultrasound was used in diagnosis of diastrophic dysplasia as early as the 13th week of pregnancy. We think that prenatal diagnosis of diastrophic dysplasia can be possible even at first trimester.

MTHFR 677TT genotype and disease risk: is there a modulating role for B-vitamins?

Methylenetetrahydrofolate reductase (MTHFR) is a critical folate-metabolising enzyme which requires riboflavin as its co-factor. A common polymorphism (677C→T) in the MTHFR gene results in reduced MTHFR activity in vivo which in turn leads to impaired folate metabolism and elevated homocysteine concentrations. Homozygosity for this polymorphism (TT genotype) is associated with an increased risk of a number of conditions including heart disease and stroke, but there is considerable variability in the extent of excess risk in various reports. The present review will explore the evidence which supports a role for this polymorphism as a risk factor for a number of adverse health outcomes, and the potential modulating roles for B-vitamins in alleviating disease risk. The evidence is convincing in the case which links this polymorphism with hypertension and hypertensive disorders of pregnancy, particularly preeclampsia. Furthermore, elevated blood pressure was found to be highly responsive to riboflavin intervention specifically in individuals with the MTHFR 677TT genotype. Future intervention studies targeted at these genetically predisposed individuals are required to further investigate this novel gene-nutrient interaction. This polymorphism has also been associated with an increased risk of neural tube defects (NTD) and other adverse pregnancy outcomes; however, the evidence in this area has been inconsistent. Preliminary evidence has suggested that there may be a much greater need for women with the MTHFR 677TT genotype to adhere to the specific recommendation of commencing folic acid prior to conception for the prevention of NTD, but this requires further investigation.

Diastrophic dysplasia: prenatal diagnosis and review of the literature

CONTEXT

Diastrophic dysplasia is a type of osteochondrodysplasia caused by homozygous mutation in the gene DTDST (diastrophic dysplasia sulfate transporter gene). Abnormalities occurring particularly in the skeletal and cartilaginous system are typical of the disease, which has an incidence of 1 in 100,000 live births.

CASE REPORT

The case of a pregnant woman, without any consanguineous relationship with her husband, whose fetus was diagnosed with skeletal dysplasia based on ultrasound findings and DNA tests, is described. An obstetric ultrasound scan produced in the 16th week of gestation revealed characteristics that guided the clinical diagnosis. Prominent among these characteristics were rhizomelia of the lower and upper limbs (shortening of the proximal portions) and mesomelia (shortening of the intermediate portions). Both upper limbs showed marked curvature, with the first finger of the upper limbs in abduction and clinodactyly of the fifth finger. Molecular analysis using the polymerase chain reaction (PCR) and gene sequencing detected mutations that had already been described in the literature for the gene DTDST, named c.862C > T and c.2147_2148insCT. Therefore, the fetus was a compound heterozygote, carrying two different mutations.

CONCLUSIONS

Prenatal diagnosis of this condition allowed a more realistic interpretation of the prognosis, and of the couple's reproductive future. This case report shows the contribution of molecular genetics towards the prenatal diagnosis, for which there are few descriptions in the literature.