Microarray-Based Comparative Genomic Hybridization, Multiplex Ligation-Dependent Probe Amplification, and High-Resolution Karyotype for Differential Diagnosis Oculoauriculovertebral Spectrum: A Systematic Review

Comparison of different genetic testing modalities applied in paediatric patients with steroid-resistant nephrotic syndrome

BACKGROUND

Steroid-resistant nephrotic syndrome (SRNS) are monogenic in some cases, however, there are still no clear guidelines on genetic testing in the clinical practice of SRNS in children.

METHODS

Three hundred thirty-two children were diagnosed with SRNS, and all children underwent genetic testing, including gene panels and/or whole-exome/genome sequencing (WES/WGS), during treatment. We analysed the relationship between clinical manifestation and genotype, and compared different genetic testing methods' detection rates and prices.

RESULTS

In this study, 30.12% (100/332) of children diagnosed with SRNS had monogenic causes of the disease. With 33.7% (122/332) of children achieving complete remission, 88.5% (108/122) received steroids combined with tacrolimus (TAC). In detectability, WES increased by 8.69% (4/46) on gene panel testing, while WGS increased by 4.27% (5/117) on WES, and WES was approximately 1/7 of the price of WGS for every further 1% increase in pathogenicity.

CONCLUSIONS

We verified that steroids combined with TAC were the most effective option in paediatric SRNS. In detection efficiency, we found that WGS was the highest, followed by WES. The panel was the lowest, but the most cost-effective method when considering the economic-benefit ratio, and thus it should be recommended first in SRNS.

Craniofacial Microsomia, Associated Congenital Anomalies, and Risk Factors in 63 Cases from the Alberta Congenital Anomalies Surveillance System

OBJECTIVE

To report associated congenital anomalies with unexplained craniofacial microsomia (CFM) and the phenotypic overlap with other recurrent constellations of embryonic malformations (RCEM), and to assess prenatal and perinatal risk factors.

STUDY DESIGN

This is a retrospective cross-sectional study. Cases with CFM, delivered between January 1, 1997, and December 31, 2019, were abstracted from the population-based Alberta Congenital Anomalies Surveillance System. Livebirths, stillbirths, and early fetal losses were reviewed to include all types of pregnancy outcomes along the spectrum of this condition. Prenatal and perinatal risk factors were compared with the Alberta birth population to assess differences between the 2 groups.

RESULTS

There were 63 cases with CFM, yielding a frequency of 1 per 16 949. There was a high rate of cases (65%) with anomalies outside the craniofacial and vertebral regions. Congenital heart defects were the most common (33.3%). A single umbilical artery was found in 12.7% of cases. The twin/triplet rate of 12.7% was significantly higher than the Alberta rate of 3.3% (P < .0001). There was an overlap with a second RCEM condition in 9.5% of cases.

CONCLUSIONS

Although CFM is primarily a craniofacial condition, the majority of cases have congenital anomalies affecting other systems requiring additional assessments, including an echocardiogram, renal ultrasound examination, and a complete vertebral radiograph. The high rate of an associated single umbilical artery raises the possibility of a related etiological mechanism. Our findings support the proposed concept of RCEM conditions.

Fluorescence in situ hybridization (FISH) as an irreplaceable diagnostic tool for Williams-Beuren syndrome in developing countries: a literature review

OBJECTIVE

The aim of this study was to sum up and characterize all Williams-Beuren syndrome cases diagnosed by fluorescence in situ hybridization (FISH) since its implementation, as well as to discuss FISH as a cost-effective methodology in developing countries.

DATA SOURCE

From January 1986 to January 2022, articles were selected using the databases in PubMed (Medline) and SciELO. The following terms were used: Williams syndrome and In Situ Hybridization, Fluorescence. Inclusion criteria included Williams-Beuren syndrome cases diagnosed by FISH with a stratified phenotype of each patient. Only studies written in English, Spanish, and Portuguese were included. Studies with overlapping syndromes or genetic conditions were excluded.

DATA SYNTHESIS

After screening, 64 articles were included. A total of 205 individuals with Williams-Beuren syndrome diagnosed by FISH were included and further analyzed. Cardiovascular malformations were the most frequent finding (85.4%). Supravalvular aortic stenosis (62.4%) and pulmonary stenosis (30.7%) were the main cardiac alterations described.

CONCLUSIONS

Our literature review reinforces that cardiac features may be the key to early diagnosis in Williams-Beuren syndrome patients. In addition, FISH may be the best diagnostic tool for developing nations that have limited access to new technologic resources.

The Enigmatic Etiology of Oculo-Auriculo-Vertebral Spectrum (OAVS): An Exploratory Gene Variant Interaction Approach in Candidate Genes

The clinical diagnosis of oculo-auriculo-vertebral spectrum (OAVS) is established when microtia is present in association with hemifacial hypoplasia (HH) and/or ocular, vertebral, and/or renal malformations. Genetic and non-genetic factors have been associated with microtia/OAVS. Although the etiology remains unknown in most patients, some cases may have an autosomal dominant, autosomal recessive, or multifactorial inheritance. Among the possible genetic factors, gene−gene interactions may play important roles in the etiology of complex diseases, but the literature lacks related reports in OAVS patients. Therefore, we performed a gene−variant interaction analysis within five microtia/OAVS candidate genes (HOXA2, TCOF1, SALL1, EYA1 and TBX1) in 49 unrelated OAVS Mexican patients (25 familial and 24 sporadic cases). A statistically significant intergenic interaction (p-value < 0.001) was identified between variants p.(Pro1099Arg) TCOF1 (rs1136103) and p.(Leu858=) SALL1 (rs1965024). This intergenic interaction may suggest that the products of these genes could participate in pathways related to craniofacial alterations, such as the retinoic acid (RA) pathway. The absence of clearly pathogenic variants in any of the analyzed genes does not support a monogenic etiology for microtia/OAVS involving these genes in our patients. Our findings could suggest that in addition to high-throughput genomic approaches, future gene−gene interaction analyses could contribute to improving our understanding of the etiology of microtia/OAVS.

Genetics of craniofacial malformations

The field of craniofacial malformations is comprehensive and does not allow to discuss all craniofacial malformations which have been described as single entities. Many of the syndromes with craniofacial malformations are ultrarare. In this review we have chosen craniofacial malformation syndromes which are of relevance for the pediatrician, especially neonatologist: different types of craniosynostoses, oculo-auriculo-vertebral spectrum, Pierre Robin sequence and Treacher Collins syndrome. These syndromes will be described in detail. Diagnostic and therapeutic options will be discussed.

Case of oculo-auriculo-vertebral spectrum: rare clinical features

A 2-month-old boy presented to us with bilateral microtia, left lower motor neuron facial palsy, micrognathia, hemivertebra, bifid rib, bifid thumb and absent/hypoplastic right-sided depressor anguli oris. He had bilateral external auditory canal atresia, although response to loud sound was present. Brain stem evoked response audiometry (BERA) was advised at 3 months of age. Karyotype was normal. We diagnosed him as a case of oculo-auriculo-vertebral spectrum. Child was discharged on request by the family with the plan for bone-anchored hearing aid after BERA and plan for pinna and ear canal reconstruction at a later age but child did not come for any follow-up visit. On telephonic enquiry, it was found that he is thriving well but has developmental delay including speech delay. We conclude that children presenting with external ear abnormalities should be screened for multiple congenital anomalies so that a multidisciplinary approach to management can be planned.