Array-CGH analysis in Rwandan patients presenting development delay/intellectual disability with multiple congenital anomalies

VPS51 biallelic variants cause microcephaly with brain malformations: A confirmatory report

Whole exome sequencing undertaken in two siblings with delayed psychomotor development, absent speech, severe intellectual disability and postnatal microcephaly, with brain malformations consisting of cerebellar atrophy in the eldest affected and hypoplastic corpus callosum in the younger sister; revealed a homozygous intragenic deletion in VPS51, which encodes the vacuolar protein sorting-associated protein, one the four subunits of the Golgi-associated retrograde protein (GARP) and endosome-associated recycling protein (EARP) complexes that promotes the fusion of endosome-derived vesicles with the trans-Golgi network (GARP) and recycling endosomes (EARP). This observation supports a pathogenic effect of VPS51 variants, which has only been reported previously once, in a single child with microcephaly. It confirms the key role of membrane trafficking in normal brain development and homeostasis.

Clinical, cytogenetic, and molecular findings in a fetus with ultrasonic multiple malformations, 4q duplication, and 7q deletion: A case report and literature review

RATIONALE

Chromosome deletion/duplication has been reported to be associated with mental disability and dysmorphism according to the accumulated research evidence.

PATIENT CONCERNS

A 25-year-old woman underwent amniocentesis for cytogenetic and single-nucleotide polymorphism (SNP) array analysis at 18 weeks of gestation due to the increased Down syndrome risk of 1/13.

DIAGNOSES

The fetal chromosomal analysis revealed a seemingly "normal" chromosomal karyotype, but the SNP array results showed a partial duplication of chromosome 4q34.1q35.2 and a deletion of chromosome 7q34q36.3fluorescence in situ hybridization (FISH) analysis showed that the couple had normal chromosome 4 and 7, whereas there was a partial signal fragment of chromosome 4 attached on the long arm of chromosome 7 for the fetus.

INTERVENTIONS

The couple finally chose to terminate the pregnancy based on the ultrasonic multiple malformations and the abnormal SNP array results.

OUTCOMES

The duplicated/deleted segments of the fetus were de novo. Meanwhile, we consider SHH and XRCC2 as good candidate genes, which may, in part, explain the observed abnormalities for the fetus.

LESSONS

The combination of SNP array and FISH analysis can give a molecular chromosomal diagnosis, which will offer more clear cytogenetic diagnosis and genetic counseling.

A comprehensive clinical and genetic study in 127 patients with ID in Kinshasa, DR Congo

Pathogenic variants account for 4 to 41% of patients with intellectual disability (ID) or developmental delay (DD). In Sub-Saharan Africa, the prevalence of ID is thought to be higher, but data in Central Africa are limited to some case reports. In addition, clinical descriptions of some syndromes are not available for this population. This study aimed at providing an estimate for the fraction of ID/DD for which an underlying etiological genetic cause may be elucidated and provide insights into their clinical presentation in special institutions in a Central African country. A total of 127 patients (33 females and 94 males, mean age 10.03 ± 4.68 years), were recruited from six institutions across Kinshasa. A clinical diagnosis was achieved in 44 but molecular confirmation was achieved in 21 of the 22 patients with expected genetic defect (95% clinical sensitivity). Identified diseases included Down syndrome (15%), submicroscopic copy number variants (9%), aminoacylase deficiency (0.8%), Partington syndrome in one patient (0.8%) and his similarly affected brother, X-linked syndromic Mental Retardation type 33 (0.8%), and two conditions without clear underlying molecular genetic etiologies (Oculo-Auriculo-Vertebral and Amniotic Bands Sequence). We have shown that genetic etiologies, similar to those reported in Caucasian subjects, are a common etiologic cause of ID in African patients from Africa. We have confirmed the diagnostic utility of clinical characterization prior to genetic testing. Finally, our clinical descriptions provide insights into the presentation of these genetic diseases in African patients.

Phenotypic Analysis of Korean Patients with Abnormal Chromosomal Microarray in Patients with Unexplained Developmental Delay/Intellectual Disability

PURPOSE

The present study aimed to investigate chromosomal microarray (CMA) and clinical data in patients with unexplained developmental delay/intellectual disability (DD/ID) accompanying dysmorphism, congenital anomalies, or epilepsy. We also aimed to evaluate phenotypic clues in patients with pathogenic copy number variants (CNVs).

MATERIALS AND METHODS

We collected clinical and CMA data from patients at Konyang University Hospital between September 2013 and October 2014. We included patients who had taken the CMA test to evaluate the etiology of unexplained DD/ID.

RESULTS

All of the 50 patients identified had DD/ID. Thirty-nine patients had dysmorphism, 19 patients suffered from epilepsy, and 12 patients had congenital anomalies. Twenty-nine of the 50 patients (58%) showed abnormal results. Eighteen (36%) were considered to have pathogenic CNVs. Dysmorphism (p=0.028) was significantly higher in patients with pathogenic CNVs than in those with normal CMA. Two or more clinical features were presented by 61.9% (13/21) of the patients with normal CMA and by 83.3% (15/18) of the patients with pathogenic CMA.

CONCLUSION

Dysmorphism can be a phenotypic clue to pathogenic CNVs. Furthermore, pathogenic CNV might be more frequently found if patients have two or more clinical features in addition to DD/ID.

22q11.2 deletion syndrome in diverse populations

22q11.2 deletion syndrome (22q11.2 DS) is the most common microdeletion syndrome and is underdiagnosed in diverse populations. This syndrome has a variable phenotype and affects multiple systems, making early recognition imperative. In this study, individuals from diverse populations with 22q11.2 DS were evaluated clinically and by facial analysis technology. Clinical information from 106 individuals and images from 101 were collected from individuals with 22q11.2 DS from 11 countries; average age was 11.7 and 47% were male. Individuals were grouped into categories of African descent (African), Asian, and Latin American. We found that the phenotype of 22q11.2 DS varied across population groups. Only two findings, congenital heart disease and learning problems, were found in greater than 50% of participants. When comparing the clinical features of 22q11.2 DS in each population, the proportion of individuals within each clinical category was statistically different except for learning problems and ear anomalies (P < 0.05). However, when Africans were removed from analysis, six additional clinical features were found to be independent of ethnicity (P ≥ 0.05). Using facial analysis technology, we compared 156 Caucasians, Africans, Asians, and Latin American individuals with 22q11.2 DS with 156 age and gender matched controls and found that sensitivity and specificity were greater than 96% for all populations. In summary, we present the varied findings from global populations with 22q11.2 DS and demonstrate how facial analysis technology can assist clinicians in making accurate 22q11.2 DS diagnoses. This work will assist in earlier detection and in increasing recognition of 22q11.2 DS throughout the world.

Cytogenetic Studies of Rwandan Pediatric Patients Presenting with Global Developmental Delay, Intellectual Disability and/or Multiple Congenital Anomalies

Global developmental delay (GDD) is defined as a significant delay in two or more developmental domains: gross or fine motor, speech/language, cognitive, social/personal and activities of daily living. Many of these children will go on to be diagnosed with intellectual disability (ID), which is most commonly defined as having an IQ <75 in addition to impairment in adaptive functioning. Cytogenetic studies have been performed in 664 Rwandan pediatric patients presenting GDD/ID and/or multiple congenital abnormalities (MCA). Karyotype analysis was performed in all patients and revealed 260 chromosomal abnormalities. The most frequent chromosomal abnormality was Down syndrome and then Edward syndrome and Patau syndrome. Other identified chromosomal abnormalities included 47,XX,+del(9)(q11), 46,XY,del(13)(q34) and 46,XX,der(22)t(10;22)(p10;p10)mat. In conclusion, our results highlight the high frequency of cytogenetically detectable abnormalities in this series, with implications for the burden on the healthcare. This study demonstrates the importance of cytogenetic analysis in patients with GDD/ID and MCA.

Medical genetics and genomic medicine in Rwanda

Medical genetics and genomic medicine in Rwanda.