Case Report: Novel rare mutation c.6353C > G in the ABCA12 gene causing harlequin ichthyosis identified by whole exome sequencing.

Background: Harlequin ichthyosis (HI) is a severe rare genetic disease that mainly affects the skin. Neonates with this disease are born with thick skin and large diamond-shaped plates covering most of their bodies. Affected neonates lose the ability to control dehydration and regulate temperature and are more susceptible to infections. They also face respiratory failure and feeding problems. These clinical symptoms are factors associated with high mortality rates of neonates with HI. Until now, there are still no effective treatments for HI patients and most patients die in the newborn period. Mutation in the ABCA12 gene, which encodes an adenosine triphosphate-binding cassette (ABC) transporter, has been demonstrated as the major cause of HI. Case presentation: In this study, we report the case who is one infant that was born prematurely at 32 gestational weeks with the whole body covered with thick plate-like scales of skin. The infant was severely infected with mild edema, multiple cracked skins full of the body, yellow discharge, and necrosis of fingers and toes. The infant was suspected to be affected by HI. Whole exome sequencing (WES) was performed as a tool for detecting the novel mutation in one prematurely born Vietnam infant with HI phenotype. And after that, the mutation was confirmed by the Sanger sequencing method in the patient and the members of his family. In this case, one novel mutation c.6353C > G (p.S2118X, Hom) in the ABCA12 gene, was detected in the patient. The mutation has not been reported in any HI patients previously. This mutation was also found in a heterozygous state in the members of the patient's family, including his parents, an older brother, and an older sister who are no symptoms. Conclusions: In this study, we identified a novel mutation in a Vietnamese patient with HI by whole exome sequencing. The results for the patient and the members of his family will be helpful in understanding the etiology of the disease, diagnosing carriers, assisting in genetic counseling, and emphasizing the need for DNA-based prenatal screening for families with a history of the disease.

Whole exome sequencing analysis in a couple with three children who died prematurely due to carnitine-acylcarnitine translocase deficiency.

OBJECTIVE: We investigated a strategy of exome sequencing DNA from the unaffected parents and applied a set of filtering criteria to identify genes where both partners are heterozygous for a potentially pathogenic variant. CASE REPORT: We report a non-consanguineous couple who had three daughters, all spontaneous preterm birth at 36 weeks gestation and died in the first period after birth, suspected inborn errors of metabolism. Two days after birth, the first daughter presented with difficulty breathing, cyanosis and died; the second died at 33 days old; the third daughter was isolated under special care and was taken to the mother's room, developed the same symptoms and died after 5 days. Dried blood spot testing screen of 55 congenital metabolic disorders was negative. CONCLUSION: Heterogenous variant in SLC25A20 gene was found in both parents, contributing to the delineations of the neonatal phenotypes related to SLC25A20 mutation in CACTD.

Microcephaly primary hereditary (MCPH): Report of novel ASPM variants and prenatal diagnosis in a Vietnamese family.

OBJECTIVE: MCPH (microcephaly primary hereditary) is a group of autosomal recessive developmental disorders with microcephaly present at birth and intellectual disability. Since a second trimester ultrasound is not able to detect subtypes with minimal prenatal presentations, only prenatal diagnosis by genetic testing can confirm these cases and allow for effective genetic counseling, especially a family with a previously affected child. CASE REPORT: A 37-year-old women was pregnant for the third time and had two prior children with profound microcephaly and mental retardation. Targeted panel sequencing identified novel compound heterozygous ASPM pathogenic variants: c.1615_1616del (p. Glu539ArgfsTer15); c.∗293T > A (p. Leu98Ter), which confirmed the diagnosis of MCPH5 (#OMIM 608716). Genetic testing was conducted for family members and applied on prenatal diagnosis. CONCLUSION: This is the first cases of MCPH5 to be reported in Vietnam and the genetic result aided in prenatal diagnosis of a high-risk pregnancy. The study highlights the importance of genetic testing in defining definitive diagnosis which allowed for timely prenatal diagnosis and genetic counseling for the family.

A case of self-improving collodion ichthyosis in Vietnam.

Autosomal recessive congenital ichthyosis is a heterogeneous group of congenital disorders characterized by aberrant skin cornification and diffuse skin scaling. Some patients with this condition are born encased in a collodion membrane which is later shed, revealing the underlying skin disorder. Self-healing collodion baby (SHCB) is a less common phenotype of this disorder, accounting for about 10% of the patients, in which the membrane peels after several weeks, leaving no underlying skin aberration. Here, we report and discuss the diagnosis and management of an infant with SHCB in Vietnam due to compound heterozygous pathogenic mutations in TGM1.