Symmetrical terminal transverse limb defects: report of a twenty-week fetus

Vascular limb defects and maternal age

BACKGROUND

The prenatal diagnosis procedure chorionic villus sampling is associated with increased risk of vascular disruption limb defects. Some studies have suggested that these defects are more common among infants born to women 35 years and older while other studies have shown a correlation with younger mothers.

METHODS

All infants with vascular disruption defects were identified in the Active Malformations Surveillance Program at Brigham and Women's Hospital in the years 1972-1974, 1979-2011. We compared the rate of occurrence of infants with vascular limb defects among women in theses age groups: ≤19, 20 to 34, and ≥35 years to the rate of occurrence of infants with preaxial polydactyly, adjusting for race. Infants with an identifiable cause of their defects were excluded.

RESULTS

106 infants with vascular disruption defects and 67 with preaxial polydactyly were identified. Seventeen percent of the infants with vascular disruption defects and 25% of the infants with preaxial polydactyly were born to women 35 and older (p = 0.23). In contrast, 16% of the infants with vascular disruption defects were born to young mothers (≤19 years) compared with 6.0% of the mothers of infants with preaxial polydactyly (adjusted odds ratio vs. 35+ years = 5.3, 95% confidence interval 1.4-21, p = 0.017).

CONCLUSION

Women 35 years old or older did not have increased risk for having a child with vascular disruption defects, but these defects were more common among infants of young (≤19) mothers, compared with the preaxial polydactyly group.

Prenatal two- and three-dimensional ultrasound diagnosis of limb reduction defects associated with homozygous alpha-thalassemia

OBJECTIVES

We present the prenatal two-dimensional (2D-) and three-dimensional ultrasound (3D-US) diagnosis of limb reduction defects associated with homozygous alpha-thalassemia and a review of the literature.

METHODS

At 17 weeks' gestation, amniocentesis was performed for cytogenetic and molecular studies, and 2D- and 3D-US examinations were made for evaluation of the fetal malformations.

RESULTS

Amniocentesis revealed a 46,XY karyotype and molecular analysis of the amniocytes showed that the fetus was homozygous for the Southeast Asian deletion (--SEA/--SEA). 2D-US examination revealed bilateral ventriculomegaly, brachycephaly, pleural effusion, digital deficiency and hypoplasia of the right foot, and digital deficiency of the left foot. 3D-US confirmed the distal limb reduction defects.

CONCLUSIONS

When the fetus is at risk for homozygous alpha-thalassemia, 2D- and 3D-US examinations are useful for prenatal detection of the associated limb reduction defects. Prenatal identification of the possible association with limb reduction defects is important for parental counseling and decision-making when intrauterine fetal therapy is an option.

Vascular-type disruptive defects in fetuses with homozygous α-thalassemia: report of two cases and review of the literature

BACKGROUND

The thalassemias are an inherited group of heterogeneous anemias in which one or more of the globin chains in the hemoglobin tetramer are absent. Fetuses with homozygous alpha-thalassemia, which is particularly prevalent in people of Southeast Asian extraction, experience deficient alpha-globin chain synthesis and cannot produce hemoglobin F (the primary fetal hemoglobin after 8 weeks' gestation). Instead, they produce an anomalous hemoglobin, hemoglobin Bart's, with an unusually high affinity for oxygen, leading to profound anemia and tissue hypoxia.

METHODS AND RESULTS

Here we report on two fetuses with homozygous alpha-thalassemia who displayed structural defects of a vascular disruptive type. Both fetuses demonstrated limb anomalies, including terminal transverse limb deficiencies, and one fetus was found to have a brain malformation consisting of a neuronal migrational defect. The limb anomalies and suspected brain malformation were detected on prenatal ultrasound prior to confirmation of the diagnosis of alpha-thalassemia in one case; in the other case prenatal records were not available. While microcephaly, hydrocephalus, and retarded brain growth have been rarely reported in association with homozygous alpha-thalassemia, this is the first report of a true brain malformation in an affected fetus. Limb anomalies, on the other hand, appear to be more frequent. Recently, aggressive in utero and postnatal therapies for homozygous alpha-thalassemia have been attempted with some success.

CONCLUSIONS

Our cases and those from the medical literature suggest that couples need to be counseled about the risks of congenital anomalies of a vascular disruptive type in affected fetuses. Furthermore, data from the literature suggests that in utero therapy may not significantly decrease these risks as such anomalies may be present prior to the institution of therapy. In addition, in hydropic infants with vascular disruptive defects, especially in those of Southeast Asian origin, homozygous alpha-thalassemia should be suspected as a likely etiology.

Unilateral transverse arm defect with subterminal digital nubbins

We present a case of unilateral terminal transverse forearm deficiency with subterminal digit-like nubbins, identified in a fetus from a pregnancy terminated electively in the second trimester because the distal right arm and hand could not be seen by ultrasound and were presumed to be absent. Pathologic evaluation showed distal transverse shortening, tapering to a point in the mid-forearm. Five primitive digital nubbins were present, located just proximal to the tapered point. The arm vessels appeared normal histologically, and the amnion showed no evidence of intrauterine disruption. Histologic examination of the nubbins revealed osteocartilaginous tissue, never described previously within digital nubbins. This fetus has the rare phenotype of terminal transverse limb defects with residual nubbins, but differs in that the nubbins are not at the tip of the terminal transverse limb defect.

Maternal homozygosity for the common MTHFR mutation as a potential risk factor for offspring with limb defects

A common mutation, C677T, in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene leads to altered homocysteine metabolism, and has been associated with the occurrence of neural tube defects (NTD). Administration of folic acid decreases this risk. There is also evidence that periconceptional supplementation of mothers with folic acid can decrease the risk of limb defects in the offspring. Here we describe a child with a transverse terminal defect of one hand, whose mother is homozygous for the C677T MTHFR mutation. We suggest that homozygosity for the MTHFR mutation may be a risk factor for transverse terminal limb defect/s by an effect mediated through altered folate and homocysteine metabolism. Further studies of mothers of infants with limb reduction defects for the MTHFR mutation may be of help in establishing this association. A simple intervention in the form of folic acid supplementation would be protective, should an association be established.

Severe terminal transverse limb reduction defects in homozygous Southeast-Asian alpha-thalassaemia-1

A rare occurrence of a homozygous a-thalassaemia fetus with severe terminal transverse limb reduction defects involving all limbs is reported. When prenatal testing, either by DNA analysis or haemoglobin electrophoresis, indicating a fetus with homozygous alpha-thalassaemia, a complete sonographic survey of fetal limbs is mandatory, and terminal transverse limb reduction defects should be included in genetic counselling prior to in utero fetal therapy.

Limb defects and congenital anomalies of the genitalia in an infant with homozygous alpha-thalassemia

We describe an infant with homozygous alpha-thalassemia, genital abnormalities, and terminal transverse limb defects, whose limbs demonstrate evidence of loss of tissue and abnormal morphogenesis. We propose these defects were due to either severe fetal anemia or to vascular occlusion by abnormal erythrocytes, resulting in hypoxia of the developing distal limbs and genitalia.

Limb defects in homozygous alpha-thalassemia: report of three cases

Homozygosity for the South-Asian alpha-thalassemia (--SEA/) deletion is a serious hematological condition that results, in most cases, in intrauterine or postnatal death due to anemia and severe hypoxia of prenatal onset. A relationship between congenital abnormalities and intra-uterine hypoxia has been postulated. However, since homozygosity for the (--SEA/) deletion is most common in underdeveloped countries where detailed autopsies are lacking, the incidence of congenital abnormalities among these babies has not been well delineated. We report on three newborn infants, homozygous for the (--SEA/) deletion, who were born with limb defects. We postulate that this combination is the result of prenatal hypoxia which may affect other fetal body organs. This should be taken into consideration when prenatal treatment of affected fetuses, with intrauterine blood transfusion, is suggested.