Minimally invasive fetal autopsy using ultrasound: a feasibility study

OBJECTIVES

To evaluate postmortem ultrasound (PM-US) for minimally invasive autopsy, and to demonstrate its feasibility, sensitivity and specificity, as compared with conventional autopsy, in detecting major congenital abnormalities.

METHODS

Over a 19-month study period from 1 March 2012 to 30 September 2013, we recruited from a referral hospital 88 consecutive fetuses, at 11-40 weeks' gestation, which had undergone termination, miscarriage or intrauterine fetal death. We performed PM-US using different transducers and compared the data with those from conventional autopsy. The latter was performed, according to the Societé Francaise de Foetopathologie (France) guidelines, by experienced perinatal pathologists who were blinded to the ultrasound data.

RESULTS

Complete virtual autopsy by ultrasound was possible in 95.5% of the cases. The sensitivity of PM-US for detecting brain abnormalities was 90.9% (95% CI, 58.7-99.8%) and the specificity was 87.3% (95% CI, 75.5-94.7%). In 20% of cases, a neuropathological examination was not possible due to severe maceration. The sensitivity for detection of thoracic abnormalities was 88.9% (95% CI, 65.3-98.6%) and the specificity was 92.8% (95% CI, 84.1-97.6%), and the sensitivity for detection of abdominal anomalies was 85.7% (95% CI, 57.2-98.2%) and the specificity was 94.6% (95% CI, 86.7-98.5%).

CONCLUSION

This pilot study confirms the feasibility of PM-US for virtual autopsy as early as 11 weeks' gestation. This new technique shows high sensitivity and specificity in detecting congenital structural abnormalities as compared with conventional autopsy. Copyright © 2014 ISUOG. Published by John Wiley & Sons Ltd.

Prenatally diagnosed periventricular nodular heterotopia: Further delineation of the imaging phenotype and outcome

OBJECTIVES

Periventricular nodular heterotopia (PNH) is a malformation of cortical development which presents with heterogeneous imaging, neurological phenotype and outcome. There is a paucity of comprehensive description detailing the prenatal diagnosis of PNH. The aim of this study is to report neuroimaging features and correlated outcomes in order to delineate the spectrum of prenatally diagnosed PNH.

METHODS

It was a retrospective study over 15 years in five tertiary centers. All fetuses with prenatally diagnosed PNH were collected. Fetal ultrasound and MRI were reviewed and genetic screening collected. Prenatal findings were analyzed in correlation to fetopathological analyses and post-natal follow up.

RESULTS

Thirty fetuses (22 females and 8 males) with PNH were identified. The two major ultrasound signs were ventriculomegaly associated with dysmorphic frontal horns (60%) and posterior fossa anomalies (73.3%). On MRI, two groups of PNH were identified: the contiguous and diffuse PNH (n = 15, 50%), often associated with megacisterna magna, and the non-diffuse, either anterior, posterior or unilateral PNH. FLNA mutations were found in 6/11 cases with diffuse PNH. Additional cortical malformations were exclusively observed in non diffuse PNH (9/15; 60%). Twenty-four pregnancies (80%) were terminated. Six children aged 6 months to 5 years are alive. Five have normal neurodevelopment (all had diffuse PNH) whereas one case with non diffuse PNH has developmental delay and epilepsy.

CONCLUSION

PNH is heterogeneous but patients with diffuse PNH are a common subgroup with specific findings on prenatal imaging and implications for prenatal counseling.

Refining the phenotypical and mutational spectrum of Taybi-Linder syndrome

Taybi-Linder syndrome (TALS, OMIM 210710) is a rare autosomal recessive disorder belonging to the group of microcephalic osteodysplastic primordial dwarfisms (MOPD). This syndrome is characterized by short stature, skeletal anomalies, severe microcephaly with brain malformations and facial dysmorphism, and is caused by mutations in RNU4ATAC. RNU4ATAC is transcribed into a non-coding small nuclear RNA which is a critical component of the minor spliceosome. We report here four foetuses and four unrelated patients with RNU4ATAC mutations. We provide antenatal descriptions of this rare syndrome including unusual features found in two twin foetuses with compound heterozygosity for two rare mutations who presented with mild intrauterine growth retardation and atypical dysmorphic facial features. We also carried out a literature review of the patients described up to now with RNU4ATAC mutations, affected either with TALS or Roifman syndrome, a recently described allelic disorder.

Neuropathological review of 138 cases genetically tested for X-linked hydrocephalus: evidence for closely related clinical entities of unknown molecular bases

L1 syndrome results from mutations in the L1CAM gene located at Xq28. It encompasses a wide spectrum of diseases, X-linked hydrocephalus being the most severe phenotype detected in utero, and whose pathophysiology is incompletely understood. The aim of this study was to report detailed neuropathological data from patients with mutations, to delineate the neuropathological criteria required for L1CAM gene screening in foetuses by characterizing the sensitivity, specificity and positive predictive value of the cardinal signs, and to discuss the main differential diagnoses in non-mutated foetuses in order to delineate closely related conditions without L1CAM mutations. Neuropathological data from 138 cases referred to our genetic laboratory for screening of the L1CAM gene were retrospectively reviewed. Fifty-seven cases had deleterious L1CAM mutations. Of these, 100 % had hydrocephalus, 88 % adducted thumbs, 98 % pyramidal tract agenesis/hypoplasia, 90 % stenosis of the aqueduct of Sylvius and 68 % agenesis/hypoplasia of the corpus callosum. Two foetuses had L1CAM mutations of unknown significance. Seventy-nine cases had no L1CAM mutations; these were subdivided into four groups: (1) hydrocephalus sometimes associated with corpus callosum agenesis (44 %); (2) atresia/forking of the aqueduct of Sylvius/rhombencephalosynapsis spectrum (27 %); (3) syndromic hydrocephalus (9 %), and (4) phenocopies with no mutations in the L1CAM gene (20 %) and in whom family history strongly suggested an autosomal recessive mode of transmission. These data underline the existence of closely related clinical entities whose molecular bases are currently unknown. The identification of the causative genes would greatly improve our knowledge of the defective pathways involved in these cerebral malformations.

[Hypoplasia adrenal congenita of anencephalic type: two cases with pituitary abnormalities and review of literature]

Hypoplasia adrenal congenita is an extremely uncommon disease of early onset. This condition can be lethal in the absence of treatment. Some forms are due to the congenital adrenal hypoplasia of anencephalic type whose origin is even unknown. Here, we present two cases of congenital adrenal hypoplasia of anencephalic type with pituitary abnormalities. The two male newborns died because adrenal insufficiency in the neonatal period. The adrenal glands were hypoplastic with a histological structure of anencephalic type Immunocytochemical study of the pituitary revealed an absence of the gonadotrophs. No mutation of DAX 1 and SF-1 was found.

[Genetic testing in the context of the revision of the French law on bioethics]

This article focuses on six questions raised by genetic testing in human: (1) the use of genetic tests, (2) information given to relatives of patients affected with genetic disorders, (3) prenatal and preimplantatory diagnosis for late onset genetic diseases and the use of pangenomic tests in prenatal diagnosis, (4) direct-to-consumer genetic testing, (5) population screening in the age of genomic medicine and (6) incidental findings when genetic testing are used.

Contribution of fetal MR imaging in the prenatal diagnosis of Zellweger syndrome

Zellweger syndrome (ZS), or cerebrohepatorenal syndrome, was the first described peroxisomal biogenesis disorder. It represents the most severe phenotype, and some of its multiple congenital anomalies can manifest prenatally. Fetal hypokinesia, renal hyperechogenicity, and cerebral ventricular enlargement are the most common reported fetal features. Single and/or late detectable manifestations account for most of the difficulties of prenatal diagnosis, as well as the limitations of ultrasonography itself. Prenatal diagnosis, however, can be achieved through (1) assays of concentrations of peroxisomal metabolites (very-long-chain fatty acids, bile acids, intermediates, plasmalogens), (2) activities of peroxisomal enzymes (dihydroacetone-phosphate acyltransferase), or (3) molecular screening techniques, if available. We report on the contribution of MR imaging to the diagnosis of ZS in 2 unrelated fetuses. MR imaging was performed in the third trimester because of cerebral ventricular enlargement diagnosed on routine sonography examinations. In both cases, MR imaging revealed ZS-characteristic abnormal cortical gyral patterns, impaired myelination, and cerebral periventricular pseudocysts. In addition, MR imaging revealed renal microcysts and hepatosplenomegaly in one case. The high level of resolution of MR imaging, which allows analysis of cerebral gyration and myelination, facilitates the prenatal diagnosis of complex polymalformative syndromes such as ZS.

A new lethal syndrome of exomphalos, short limbs, and macrogonadism

We report a new lethal multiple congenital abnormality (MCA) syndrome of exomphalos, short limbs, nuchal web, macrogonadism, and facial dysmorphism in seven fetuses (six males and one female) belonging to three unrelated families. X rays showed enlarged and irregular metaphyses with a heterogeneous pattern of mineralisation of the long bones. Pathological examination showed adrenal cytomegaly, hyperplasia of Leydig cells, ovarian stroma cells, and Langherans cells, and renal microcysts. We suggest that this condition is a new autosomal recessive MCA syndrome different from Beckwith-Wiedemann syndrome, especially as no infracytogenetic deletion or uniparental disomy of chromosome 11 was found.