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2004-09-07-01 Answer to the Case of the week # 130 © Camargo

Answer to case of the week # 130

November 04, 2004

Helio Camargo, MD,  Marcia Camargo, MD
Campinas, Brazil.

This is a routine ultrasound scan performed at 20 weeks of gestation for a 37-year-old woman G2P1. The relevant postnatal photographs of the fetus are shown along with the corresponding ultrasound images.
Face with normal nasal bones:

Short digits with polysyndactyly:

Lower limbs:


Path of the umbilical artery:

Cardiac outlet:

Azygous vein and aorta:

The above ultrasound images demonstrate a complex cardiac malformation, multiple skeletal malformations, and an absent spleen. The skeletal malformations included shortened femur and humerus, shortened and asymmetric tibia and fibula, abnormal angulation of the feet, polydactyly, unilateral clenched fist and dysplastic hands. The amniocentesis revealed a normal karyotype.

An echocardiogram showed situs ambiguous due to left atrial isomerism, ambiguous atrioventricular connection, discordant ventriculo-arterial connection, isolated ventricular inversion, single atrium, a bradycardia of 107 beats per minute due to sinonodal agenesis and ventricular myocardial hypertrophy.

The baby was delivered at 37.2 weeks of gestation. The newborn weighed 3210 gm, measured 44cm and had Apgar scores of 3 in the first minute and 9 in the fifth minute. The neonate was confirmed to have a complex malformation of the isomerism group, but four different echocardiograms showed conflicting specific results. One finding however, that was prenatally unsuspected was coarctation of the aorta. The initial step in the treatment was aimed at the correction of the coarctation. The baby died in the first postoperative day due to multiple organ failure.

In this case, the presence of skeletal malformations with polydactyly suggests the possibility of Bardet-Biedl syndrome type 8(1). This condition is typically characterized by mental retardation, retinal dystrophy, polydactyly, syndactyly, brachydactyly, obesity and hypogenitalism. Thus, most of its features are not bound to be diagnosed prenatally. Bardet-Biedl syndrome classically has an autosomal recessive inheritance pattern, genetically heterogeneous, with 8 loci mapped. In Bardet-Biedl syndrome type 8 there is homozygous mutation of gene TTC8 (2).

Elbedour(3), studied the echocardiograms of 22 patients with Bardet-Biedl syndrome and found cardiac involvement in 50% of the patients. Most of his findings though, were mild. Lorda-Sanchez(4) found situs inversus in one patient with Bardet-Biedl syndrome. The co-existent atrial isomerism, also known as levoisomerism, polysplenia syndrome, cardiosplenic syndrome or heterotaxy, is a situation which comprises complex cardiac malformations, splenic dysgenesis/ agenesis and a tendency for symmetrical array of organs which are usually asymmetrical.

A differential diagnosis of Smith-Lemli-Opitz syndrome (considered due to the presence of heterotaxy and postaxial polydactyly) was ruled out as this fetus did not have the associated features of microcephaly, syndactyly of 2nd-3rd toes, low birth weight and ambiguous genitalia. Short rib-polydactyly syndrome was ruled out since the ribs were normal.

1. PubMed ID : 9152295 Bardet-Biedl type 8 (OMIN 608132)
2. Katsanis N, et al. Triallelic inheritance in Bardet-Biedl syndrome, a mendelian recessive disorder. Science 293: 2256-9, 2001.
3. Elbedour K, Zucker N, Zalzstein E, Barki Y, Carmi R. Cardiac anomalies in the Bardet-Biedl syndrome: echocardiographic studies of 22 patients. Am J Med Genet 52(2): 164-9, 1994.

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