Novel homozygous GLDC variant causing late-onset glycine encephalopathy: A case report and updated review of the literature.

Glycine encephalopathy (MIM #605899) is an autosomal recessive inborn error of metabolism caused by pathogenic variants in three genes GLDC, AMT, GCSH encoding glycine cleavage enzyme system. We report an 8-year-old boy with late-onset glycine encephalopathy who harbors a novel homozygous GLDC likely pathogenic variant c.707G > A p.(Arg236Gln). Polyhydramnios was noted at fetal ultrasound. He displayed global developmental delay, craniofacial dysmorphism, convulsions. Our report expands the phenotypic and genetic spectrum of late-onset nonketotic hyperglycinemia.

Novel interstitial 2q12.3q13 microdeletion predisposes to developmental delay and behavioral problems.

Microarray-based comparative genomic hybridization (aCGH) is being increasingly applied to delineate novel genomic disorders and related syndromes in patients with developmental delay. In this study, detailed clinical and cytogenetic data of three unrelated patients with interstitial 2q12.3q13 microdeletion were described and compared with thirteen 2q12.3q13 microdeletion patients, gathered from the medical literature and public databases. 60 K aCGH analysis revealed three overlapping 2q12.3q13 microdeletions measuring 1.88 Mb in patient 1, 1.25 Mb in patient 2, and 0.41 Mb in patient 3, respectively. Confirmation and segregation studies were performed using fluorescence in situ hybridization (FISH) and quantitative real-time PCR. Variable clinical features of 2q12.3q13 microdeletion including microcephaly, prenatal growth retardation, developmental delay, short stature, behavioral problems, learning difficulties, skeletal anomalies, congenital heart defects, and features of ectodermal dysplasia were observed. The boundaries and sizes of the 2q12.3q13 deletions in the sixteen patients were different, but an overlapping region of 249 kb in 2q12.3 was defined. The SRO (smallest region of overlap) encompasses four genes, including LIMS1, RANBP2, CCDC138, and EDAR. Among these genes, RANBP2 is a strong candidate gene for neurological phenotype and genetic susceptibility to viral infections. To our knowledge, this is the first published report of 2q12.3q13 microdeletion syndrome and our observations strongly suggest that these recurrent CNVs may be a novel risk factor for developmental delay with variable expressivity and incomplete penetrance.

Novel compound heterozygous TMEM67 variants in a Vietnamese family with Joubert syndrome: a case report.

BACKGROUND: Joubert syndrome is a genetically heterogeneous autosomal recessive ciliopathy characterized by the combination of hypoplasia/aplasia of the cerebellar vermis, thickened and elongated superior cerebellar peduncles and a deep interpeduncular fossa, known as "molar tooth sign" associated with hypotonia, respiratory control disturbances and abnormal eye movements. To date, pathogenic variants in over 35 genes are known to cause autosomal recessive Joubert Syndrome, while one gene is associated with X-linked recessive inheritance. CASE PRESENTATION: We describe here a non-consanguineous Vietnamese family with Joubert syndrome, a fetus and 10-year-old developmentally delayed boy. Ultrasonography showed ventriculomegaly at 26 + 6 weeks of gestation in the fetus. The 10-year-old-boy was diagnosed with cerebral palsy of unknown origin. Clinical physical examination at the age of 10, he showed clinical features of Joubert syndrome including typical facial dysmorphism, ataxia, severe psychomotor delay, oculomotor apraxia and molar tooth sign on brain MRI. Whole exome sequencing analysis identified a novel compound heterozygous c.725A > G p.Asn242Ser and c.313-3 T > G p.Lys105Valfs*16 TMEM67 variant in the proband and the affected fetus. These two variants were inherited from each parent and confirmed by Sanger sequencing. The variant c.725A > G p.Asn242Ser was previously documented in patients with JS, the novel splice-site c.313-3 T > G p.Lys105Valfs*16 TMEM67 variant produced an aberrant transcript with the loss of four nucleotides of exon 03. CONCLUSION: This study confirms the diagnosis of Joubert syndrome in a Vietnamese family and expands the mutational spectrum of TMEM67 sequence variations. We also highlight the importance of molecular approaches to unravel underlying mechanisms of human genetic disorders. Early precise diagnosis could help provide further accurate genetic counseling for recurrence-risk assessment, future diagnostic option, management as well as treatment guidance for rare disorders.

Clinical characteristics and genetic profiles of young and adult patients with cholestatic liver disease.

BACKGROUND AND AIMS: heterozygous ABCB4, ABCB11 and ATP8B1 sequence variants were previously reported to be associated with low phospholipid-associated cholelithiasis, intrahepatic cholestasis of pregnancy, benign recurrent intrahepatic cholestasis and biliary lithiasis. The present study aimed to identify the presence of sequence variations in genes responsible for Mendelian liver disorders in patients with cholestatic liver disease. METHODS: targeted massive parallel sequencing of a panel of genes involved in bile acid homeostasis was performed in 105 young and adult patients with cholestatic liver disease in our laboratory for molecular diagnosis. The effects of novel variants were evaluated using bioinformatics prediction tools and the Protter and Phyre2 software programs were used to create 2D, 3D topology protein modeling. Genotype-phenotype correlation was established according to molecular analysis and clinical records. RESULTS: twenty novel heterozygous ABCB4 sequence variations, one heterozygous ABCB4 large intragenic deletion and only one novel missense variant in ABCB11 and ATP8B1 were identified. Interestingly, heterozygous and homozygous SLC4A2 missense variants were detected in patients with low phospholipid-associated cholelithiasis. Two patients harbored heterozygous GPBAR1 variants. Common variants such as homozygous ABCB11 p.Val444Ala and heterozygous ABCG8 p.Asp19His were also identified in 12 cases. CONCLUSIONS: forty-eight variants were identified in five genes including ABCB4, ABCB11, ATP8B1, SLC4A2 and GPBAR1, twenty-five of which were novel. This study expands the phenotypic and mutational spectrum in genes involved in bile acid homeostasis and highlights the genetic and phenotypic heterogeneity in patients with inherited liver disorders.

WAGR syndrome and congenital hypothyroidism in a child with a Mosaic 11p13 deletion.

Wilm's tumor, aniridia, genitourinary anomalies, and mental retardation (WAGR) syndrome, a rare genetic disorder, is caused by the loss of 11p13 region including PAX6 and WT1. We report novel findings in a 28-month-old boy with aniridia, Wilm's tumor, congenital hypothyroidism, and sublingual thyroid ectopia. He was found to have a mosaic 5.28 Mb interstitial deletion of chromosome 11p13 deleting PAX6 and WT1. In order to clarify the mechanism underlying his thyroid dysgenesis, sequence analysis of candidate thyroid developmental genes was performed. We identified a FOXE1: c.532_537delGCCGCC p.(Ala178_Ala179del) variant that predisposes to thyroid ectopia. Taken together, this is the first report of mosaic 11p13 deletion in association with thyroid dysgenesis. We also propose a model of complex interactions of different genetic variants for this particular phenotype in the present patient.

In vitro culture of Keratinocytes from human umbilical cord blood mesenchymal stem cells: the Saigonese culture.

There have been many attempts to acquire and culture human keratinocytes for clinical purposes including from keratotome slices in media with fetal calf serum (FCS) or pituitary extract (PE), from skin specimens in media with feeder layers, from suction blister epidermal roofs' in serum-free culture and from human umbilical cord blood (hUCB) mesenchymal stem cells (MSCs) in media with skin feeder layers. Conversely this study was designed to investigate whether keratinocytes could be obtained directly from hUCB MSCs in vitro. It is widely established that mesenchymal stem cells from human umbilical cord blood have multipotent capacity and the ability to differentiate into disparate cell lineages hUCB MSCs were directly induced to differentiate into keratinocytes by using a specific medium composed of primary culture medium (PCM) and serum free medium (SFM) in a ratio 1:9 for a period of 7 days and tested by immunostain p63 and K1-K10. Cells thus cultured were positive in both tests, confirming the possibility to directly obtain keratinocytes from MSCs hUCB in vitro.