The Incidence of Chromosomal Aberrations in Prenatally Diagnosed Isolated Agenesis of the Corpus Callosum.

PURPOSE: To establish the prevalence of chromosomal aberrations in fetuses with an apparently isolated agenesis of the corpus callosum (ACC) on prenatal ultrasound. MATERIALS & METHODS: This was a retrospective study of complete isolated ACC at the time of ultrasound evaluation with respect to karyotype information. Within this group, a subgroup with non-malformation minor abnormalities, such as a single umbilical artery (SUA), polyhydramnios or fetal growth restriction (FGR), was investigated. RESULTS: Complete ACC was diagnosed in 343 cases. Of them, 143 (41.6 %) were isolated, with 16 fetuses showing additional minor findings. In 76.2 % (109/143) karyotyping was performed. Additional array CGH analysis was performed in 7.7 % (11/143). Chromosomal aberrations were found in 4.6 % (5/109) overall, in 3.1 % (3/98) of those without any additional sonographic findings (all represented mosaic trisomy 8) and in 18.2 % (2/11) of those with minor abnormalities. The prevalence of pathogenic submicroscopic copy number variant (CNV) was 9 % (1/11). CONCLUSION: Fetal karyotyping is recommended in ACC, as trisomy 8 mosaicism should be considered despite otherwise unremarkable ultrasound. The role of novel techniques such as array CGH and its implication has to be explored in prospective studies.

Prenatal diagnosis and molecular cytogenetic characterisation of a small de novo interstitial duplication 16q11.2-q13.

We describe the first prenatally detected case of a small de novo interstitial duplication of chromosome 16q. This chromosomal aberration is extremely rare. Amniocentesis was indicated by advanced maternal age only. Ultrasound examinations of the foetus showed no abnormalities. Conventional and molecular cytogenetic analyses on cultured amniocytes by comparative genomic hybridisation (CGH) and fluorescence in situ hybridisation (FISH) using partial chromosome paints and a locus-specific YAC clone revealed a de novo direct duplication of the chromosomal region 16q11.2-q13 leading to a partial trisomy 16q (46,XX,dup(16)(q11.2q13)). There are only five postnatal reports of comparable duplications involving this chromosomal region. These patients presented with little or no associated dysmorphic features but with significant neurodevelopmental delay and severe behavioural problems. After genetic counselling, the parents opted for termination of pregnancy. Post-mortem examination showed slight facial dysmorphic signs, minor dysgenesis of the ovaries and an atypical outflow of the arteria thyroidea ima.

Isolated cardiomegaly in the second trimester as an early sign of fetal hydrops due to intracranial arteriovenous malformation.

We report the case of a 27-year-old pregnant woman in whom isolated mild fetal cardiomegaly, diagnosed prenatally on sonographic examination at 22 weeks' menstrual age, was the first sign of development of an arteriovenous malformation of the vein of Galen. The arteriovenous malformation was visualized on sonographic examination at 29 weeks' menstrual age; prenatal MRI at 32 weeks confirmed the diagnosis. At 34 weeks' menstrual age, repeat sonographic examination demonstrated polyhydramnios, cardiomegaly, and generalized hydrops with ascites and pleural effusion. After vaginal delivery, the male neonate died of respiratory distress. We present the findings of prenatal gray-scale, color Doppler, and power Doppler sonography; MRI; and postmortem examination.