Prenatal diagnosis of thanatophoric dysplasia at 24 weeks

Prenatal diagnosis of skeletal dysplasia due to FGFR3 gene mutations: a 9-year experience : prenatal diagnosis in FGFR3 gene

PURPOSE

Prenatal diagnosis with ultrasound findings compatible with skeletal dysplasia due to FGFR3 mutations over a 9 year period in pregnancies and abortuses.

METHODS

54 samples were studied. Aneuploidy studies were carried out on all samples. By sequencing analysis, we determined mutations for achondroplasia (ACH), hypochondroplasia (HCH), and type I and type II tanathophoric dysplasia (TD).

RESULTS

2 chorionic villi samples had a G380R mutation due to a mother with ACH; 4 amniotic fluid samples with TDs in which the foetuses had micromelia plus hypoplastic thoraces; 5 samples from abortuses with TDs. Neither ACH nor HCH occurred in sporadic cases.

CONCLUSIONS

Molecular studies in ongoing pregnancies are indicated in cases with an affected parent, a family history with positive molecular studies (maternal anxiety), and when the US finding demonstrates micromelia with a hypoplastic thorax. A protocol for tissues of abortuses should include an X-ray, pathologic anatomy, and genetic studies.

Skeletal anomalies

It is possible to identify many types of skeletal dysplasias and conditions involving limb deformities prenatally using ultrasound. It is likely that in the future, with the advancing technology and discoveries in molecular genetics, specific mutation analysis will become available for many of these conditions. This will make first trimester diagnosis an option in many cases. Because of the complex nature of many of these cases, it may be helpful to use a multidisciplinary approach involving a radiologist and a geneticist at times. In utero radiographs may help clarify a diagnosis. In lethal cases where a specific diagnosis has not been confirmed, it may be helpful postpartum to obtain an autopsy; photographs; complete body radiographs; karyotypic analysis; and specimens of bone, cartilage, and fetal blood for further analysis.

Prenatal diagnosis of skeletal dysplasia identified postnatally as hypochondroplasia

A short-limb skeletal dysplasia was diagnosed prenatally at 35 weeks of gestation. After birth the infant was found to have hypochondroplasia. The parents are of average stature, and the child's disorder presumably occurred as a fresh mutation. This appears to be the first reported case of hypochondroplasia diagnosed prenatally as a "non-specific skeletal dysplasia" in the absence of a family history. Evaluation after birth showed that the infant, whose parents are of normal stature, has hypochondroplasia.

The importance of early prenatal diagnosis of thanatophoric dysplasia with respect to obstetric management

A case is described in which prenatal diagnosis of thanatophoric dysplasia was made in the second trimester of pregnancy by ultrasonography and radiography. Early diagnosis allowed elective abortion to be carried out, thus avoiding possible complications later in the pregnancy.

An infant with thanatophoric dwarfism surviving 169 days

A female infant with thanatophoric dwarfism surviving 169 days is described. The genetics of the entity are briefly discussed.