Fetal Dysmorphology-Still an Essential Art. Analysis of the Limitations of Microarray in a Fetal Population and a Look Toward the Genome Sequencing Era

Fetal phenotypes of Mendelian disorders: A descriptive study from India

OBJECTIVE

Exome sequencing(ES) based diagnosis of Mendelian diseases in the fetus is limited by paucity of phenotypic information. This study reports the comprehensive phenotypes of some fetuses with Mendelian disorders.

METHODS

Next generation technology based sequencing of all coding regions of the genome(Exome sequencing) or targeted gene sequencing using Sanger or next generation platforms was performed in a cohort of deeply phenotyped, cytogenetically normal fetuses with morphological defects. Prenatal ultrasonographic phenotypes and Postmortem details including dysmorphology, histopathology, radiography were ascertained. Novel candidate genes, novel/ unusual findings and unusual genotypes in cases with confirmed Mendelian disorders are described.

RESULTS

Of the 102 fetuses sequenced, 45 (44%) achieved definitive diagnosis of a Mendelian disorder with 50 pathogenic/likely pathogenic variants. The majority (87%) were autosomal recessive, 69% families were consanguineous and 54% variants were novel. Dysmorphic syndromes, skeletal dysplasias and metabolic disorders were the commonest disease categories, ciliopathies and dystroglycanopathies commonest molecular categories. We describe the first fetal description of six monogenic diseases, and nine cases with novel histological findings. Nineteen cases had novel/ unusual findings.

CONCLUSION

This cohort demonstrates how deep fetal phenotypes of some Mendelian disorders can show novel/unusual findings which have important implications for prenatal diagnosis of these conditions. This article is protected by copyright. All rights reserved.

No. 365-Fetal and Perinatal Autopsy in Prenatally Diagnosed Fetal Abnormalities with Normal Chromosome Analysis

OBJECTIVE

To review the information on fetal and perinatal autopsies, the process of obtaining consent, and the alternative information-gathering options following a prenatal diagnosis of non-chromosomal anomalies in order to assist health care providers in providing postnatal counselling regarding diagnosis and potential recurrence risks.

OUTCOMES

To provide better counselling about fetal and perinatal autopsies for women and families who are dealing with a prenatally diagnosed non-chromosomal fetal anomaly.

EVIDENCE

Published literature was retrieved through searches of PubMed or Medline, CINAHL, and The Cochrane Library in 2010, 2011, and 2017, using appropriate key words (fetal autopsy postmortem, autopsy, perinatal postmortem examination, autopsy protocol, postmortem magnetic resonance imaging, autopsy consent, tissue retention, autopsy evaluation). Results were restricted to systematic reviews, randomized controlled trials/controlled clinical trials, and observational studies. Additional publications were identified from the bibliographies of these articles. There were no date or language restrictions. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology assessment-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

BENEFITS, HARMS, AND COSTS

This update educates readers about (1) the benefits of a fetal perinatal autopsy, (2) the consent process, and (3) the alternatives when the family declines autopsy. It also highlights the need for a standardized approach to fetal and perinatal autopsies, emphasizing pertinent additional sampling when indicated. The authors recognize that there is variability across Canada in access to the cited services and resources. As such, these recommendations were developed in an attempt to promote access and to provide a minimum standard for all provinces and territories across the country.

VALUES

The quality of evidence was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care (Table).

RECOMMENDATIONS

N° 365 -Autopsies fœtales et périnatales en cas d'anomalies fœtales diagnostiquées avant la naissance avec une analyse chromosomique normale

OBJECTIF

Examiner les données sur les autopsies fœtales et périnatales, le processus de consentement et les options de collecte de renseignements à la suite d'un diagnostic prénatal d'anomalies non chromosomiques afin d'aider les fournisseurs de soins à offrir du conseil postnatal au sujet du diagnostic et des éventuels risques de récurrence. RéSULTATS: Offrir de meilleurs conseils sur les autopsies fœtales et périnatales aux femmes et aux familles qui ont reçu un diagnostic prénatal d'anomalie fœtale non chromosomique. ÉVIDENCE: Nous avons examiné des études publiées récupérées au moyen de recherches dans PubMed, Medline, CINAHL et la Bibliothèque Cochrane en 2010, en 2011 et en 2017 à l'aide de mots-clés appropriés (« fetal autopsy postmortem », « autopsy », « perinatal postmortem examination », « autopsy protocol », « postmortem magnetic resonance imaging », « autopsy consent », « tissue retention » et « autopsy evaluation »). Nous n'avons tenu compte que des résultats provenant de revues systématiques, d'essais cliniques, randomisés ou non, et d'études observationnelles. D'autres publications ont été repérées dans les bibliographies de ces articles. Aucune restriction de date ou de langue n'a été employée. Nous avons également tenu compte de la littérature grise (non publiée) trouvée sur les sites Web d'organismes d'évaluation des technologies de la santé et d'autres organismes liés aux technologies de la santé, dans des collections de directives cliniques et dans des registres d'essais cliniques, et obtenue auprès d'associations nationales et internationales de médecins spécialistes. AVANTAGES, DéSAVANTAGES ET COUTS: La présente mise à jour renseigne les lecteurs sur : 1) les avantages de l'autopsie fœtale ou périnatale; 2) le processus de consentement; et 3) les autres options offertes aux familles qui refusent l'autopsie. Elle met également en évidence la nécessité d'adopter une démarche normalisée pour la réalisation des autopsies fœtales et périnatales, et met l'accent sur les prélèvements additionnels qui peuvent être pertinents. Les auteurs sont conscients que l'accès aux ressources et aux services mentionnés varie d'un endroit l'autre au Canada; les recommandations formulées ont donc pour but de promouvoir l'accès et de fournir une norme minimale aux provinces et aux territoires du pays.

VALEURS

La qualité des données a été évaluée au moyen des critères énoncés dans le rapport du Groupe d'étude canadien sur les soins de santé préventifs (tableau). RECOMMANDATIONS.

A Dysmorphology Based Systematic Approach Toward Perinatal Genetic Diagnosis in a Fetal Autopsy Series

BACKGROUND

This retrospective study assesses the contribution of genetic disorders in fetuses undergoing postmortem evaluation and the performance of a clinical dysmorphology based systematic approach toward genetic diagnosis.

MATERIALS AND METHODS

Ninety fetuses, including spontaneous losses and terminated pregnancies, underwent a postmortem evaluation including dysmorphological examination, radiological studies, and histopathological examination. Genetic testing including karyotyping, biochemical testing, Sanger sequencing, and exome sequencing were performed selectively.

RESULTS

A genetic etiology was concluded in 48 fetuses (55%). As a standalone test, dysmorphological examination was able to ascertain a definite genetic diagnosis in sixteen cases, histopathology in six; and karyotyping, biochemical testing and exome sequencing in two cases each (Total 28). Additionally, dysmorphology findings indicated possible genetic disorder in 20 cases.

CONCLUSION

Genetic etiologies contribute significantly to fetuses undergoing autopsy in this series. A systematic approach to postmortem fetal evaluation guided by dysmorphological examination provides high diagnostic yield toward perinatal genetic diagnosis.