Prenatal diagnosis of acrania/exencephaly/anencephaly sequence (AEAS): additional structural and genetic anomalies

The most common congenital malformations in dogs: Literature review and practical guide

Congenital malformations can affect almost 7% of canine newborns. The increase of commercial dog breeding and inbreeding used to maintain the striking characteristics of each breed, the appearance of malformations has become increasingly common, especially in brachycephalic dogs. The causes are diverse, and include genetic, nutritional, iatrogenic, and infectious factors, often making it difficult to establish a cause-consequence relationship. The high mortality associated with malformations comes not only from the fact that some are incompatible with life, but also because even if many undergo surgical treatment or correction, they require specific management, monitoring, and clinical treatment for an indefinite period of time. The most common malformations such as cleft lip and palate, hydrocephalus and anasarca have been studied for a long time, and it is currently known that brachycephalic dogs have a greater predisposition, however, for other less common conditions as gastroschisis and hypospadias, there is only a few case reports. The appearance of congenital defects in a litter leads to financial losses for the breeder, emotional losses for the owner and the veterinarian and harms the well-being of that individual. For this reason, the aim of this review article is to gather relevant information on the characteristics, diagnosis, and management of the main malformations in puppies. It is essential that the veterinarian is prepared to diagnose and treat these conditions, reducing negative impacts on animals and owners.

Exencephaly-Anencephaly Sequence Associated with Maxillary Brachygnathia, Spinal Defects, and Palatoschisis in a Male Domestic Cat

Anencephaly, a severe neural tube defect characterized by the absence of major parts of the brain and skull, is a rare congenital disorder that has been observed in various species, including cats. Considering the uncommon appearance of anencephaly, this paper aims to present anencephaly in a stillborn male kitten from an accidental inbreeding using various paraclinical methods. Histological examination of tissue samples from the cranial region, where parts of the skull were absent, revealed the presence of atypical nerve tissue with neurons and glial cells organized in clusters, surrounded by an extracellular matrix and with an abundance of blood vessels, which are large, dilated, and filled with blood, not characteristic of nerve tissue structure. In CT scans, the caudal part of the frontal bone, the fronto-temporal limits, and the parietal bone were observed to be missing. CT also revealed that the dorsal tubercle of the atlas, the dorsal neural arch, and the spinal process of the C2-C7 bones were missing. In conclusion, the kitten was affected by multiple congenital malformations, a combination of exencephaly-anencephaly, maxillary brachygnathism, closed cranial spina bifida at the level of cervical vertebrae, kyphoscoliosis, palatoschisis, and partial intestinal atresia. The importance of employing imaging techniques cannot be overstated when it comes to the accurate diagnosis of neural tube defects.

Pathogenic/likely pathogenic copy number variations and regions of homozygosity in fetal central nervous system malformations

OBJECTIVE

To explore pathogenic/likely pathogenic copy number variations (P/LP CNVs) and regions of homozygosity (ROHs) in fetal central nervous system (CNS) malformations.

METHODS

A cohort of 539 fetuses with CNS malformations diagnosed by ultrasound/MRI was retrospectively analyzed between January 2016 and December 2019. All fetuses were analyzed by chromosomal microarray analysis (CMA). Three cases with ROHs detected by CMA were subjected to whole-exome sequencing (WES). The fetuses were divided into two groups according to whether they had other structural abnormalities. The CNS phenotypes of the two groups were further classified as simple (one type) or complicated (≥ 2 types).

RESULTS

(1) A total of 35 cases with P/LP CNVs were found. The incidence of P/LP CNVs was higher in the extra-CNS group [18.00% (9/50)] than in the isolated group [5.32% (26/489)] (P < 0.01), while there was no significant difference between the simpletype and complicated-type groups. (2) In the simple-type group, the three most common P/LP CNV phenotypes were holoprosencephaly, Dandy-Walker syndrome, and exencephaly. There were no P/LP CNVs associated with anencephaly, microcephaly, arachnoid cysts, ependymal cysts, or intracranial hemorrhage. (3) Only four cases with ROHs were found, and there were no cases of uniparental disomy or autosomal diseases.

CONCLUSION

The P/LP CNV detection rates varied significantly among the different phenotypes of CNS malformations, although simple CNS abnormalities may also be associated with genetic abnormalities.