Detailed genetic and clinical analysis of a novel de novo variant in HPRT1: Case report of a female patient from Saudi Arabia with Lesch–Nyhan syndrome

Background: Hypoxanthine-guanine phosphoribosyltransferase (HPRT1) deficiency is an inborn error of purine metabolism responsible for Lesch–Nyhan syndrome (LNS). The disease is inherited in an X-linked recessive manner and predominantly affects male individuals. Female individuals can carry a mutation as heterozygotes, but typically, they are asymptomatic because of the random inactivation of the affected allele. Nevertheless, although rare, heterozygote female individuals may manifest LNS with full characteristics. Herein, we describe a female patient from Saudi Arabia with LNS.Results: The patient (a 4-year-old girl) presented with typical characteristics of the disease, which include global developmental delay, self-mutilation, hyperuricemia, hypotonia, speech delay, spasticity, and seizures. Her general biochemical laboratory results were normal except for high levels of uric acid. The abdominal MRI\MRS, mostly unremarkable, showed bilateral echogenic foci within the renal collecting system. Genetic testing (whole-exome sequencing, iterative variant filtering, segregation analysis, and Sanger sequencing) pointed a novel de novo frameshift variant in HPRT1. X-inactivation assay using HpaII showed the presence of a 100% skewed X chromosome carrying the affected allele. RT-PCR of the cDNA indicated complete loss of the expression of the normal allele.Conclusion: Our study presents a female patient who has a severe case of LNSand found to be the 15th female patient with the disease in the world. The study emphasizethe need for a streamlined protocol that will help an early and accurate diagnosis of female LNS patients to avoid unnecessary interventions that lead to costly patient care

Non-immune hydrops fetalis in Saudi family secondary to a rare genetic cause

Background: Non-immune hydrops fetalis (NIHF) is the abnormal accumulation of serous fluid in more than two fetal or neonatal interstitial spaces due to non-immune causes. It is a serious condition that requires extensive medical care as it indicates severe fetal compromise. Severe anemia, infections, heart or lung defects, and liver disease are all possible causes. Less common causes of NIHF include single gene defects and chromosomal abnormalities. Case Presentation: We report a 2-month-old girl born at 32 weeks of gestation and found to have polyhydramnios and massive congenital ascites. Whole exome sequencing (WES) identified a biallelic pathogenic variant c.617G>A p. (Cys206Tyr) in the thrombospondin 1 domain-containing protein 1 (THSD1) gene. She was misdiagnosed to have ascites secondary to liver dysfunction. Conclusion: Rare causes of fetal hydrops like THSD1 mutation need to be excluded in cases of recurrent non-immune hydrops with no obvious etiology. [JBCGenetics 2021; 4(2.000): 112-114

Congenital adrenal hyperplasia with maple syrup urine disease: an example of consanguinity impact

Background: Maple syrup urine disease (MSUD) is a rare autosomal recessive metabolically inherited disorder, caused by an abnormal function of the branched-chain α-keto acid dehydrogenase complex in the mitochondria. Case Presentation: The proband was born after a full-term pregnancy and normal vaginal delivery, with a good Apgar score (8, 9 at 1 and 5 minutes) and the birth weight of 2.5 kg with ambiguous genitalia in the form of phallus-like structure (3 cm), the fusion of labio-scrotal folds and urogenital sinus. The third day after birth, the proband was lethargic and developed hyperkalemia and hyponatremia, which required intravenous fluid therapy and hormonal replacement with hydrocortisone and fludrocortisone. The treatment was based on the positive family history of congenital adrenal hyperplasia in an older male sibling. Laboratory tests, cytogenetic study, tandem mass spectroscopy, and surgery were performed for the affected individual (II-8) using standard procedures. The laboratory and the treatment revealed significant improvements. Follow-up tandem mass spectroscopy results were observed in the normal range. The affected individual was treated with prednisone (2.5 mg bid) and Florinef (Fludrocortisone) (0.1 mg OD). The subject had regular menses, while acne and hirsutism were not observed. Conclusion: We are reporting the first case of MSUD associated with CAH, 21-hydroxylase deficiency salt-losing type and suggest that glucocorticoids might have an important role in treating MSUD cases. [JBCGenetics 2019; 2(2.000): 151-155

Phenotypic expansion of Zimmermann- Laband syndrome associated with cardiac and hearing loss: a case report

Background: ATP6V1B2 gene mutation is associated with Zimmermann-Laband syndrome 2 (ZLS2), which is a rare developmental disorder characterized by nail hypoplasia and hereditary deafness. Case Presentation: We report a new phenotypic mutation of ATP6V1B2 associated with ZLS 2. The patient has atresia of the left pulmonary artery (LPA) and features of hearing loss and nail hypoplasia. The other interesting part is that the child had two types of mutations inherited from father and mother. He is carrier for GJB2 mutation (inherited from father) and diseased with ATP6V1B2 mutation (inherited from mother). Conclusion: The association of ZLS features with absent LPA was not reported previously in the literature. This finding will add new information to the database of previously reported ATP6V1B2 rare mutations. [JBCGenetics 2021; 4(2.000): 122-125

Saudi patient with peroxisome biogenesis disorder with novel variant: a case report

Background: Peroxisomes are cells' organelles that responsible for the metabolism of branched-chain and very-long-chain fatty acids (VLCFA), polyamines, and amino acids. Peroxisomal biogenesis factor 6 (PEX6) is one of the factors required for the import of the proteins into peroxisomes. Mutation in any one of PEX genes will result in Zellweger syndrome (ZS), one of the peroxisome biogenesis disorder. Case Presentation: A 11-year-old girl referred was with central hypotonia and global developmental delay and feeding problems. She has an open and flat fontanel. Liver function tests and thyroid-stimulating hormone were elevated. Plasma VLCFA C26, VLCFA C24/C22, and VLCFA C26/C22 were elevated. Cerebrospinal fluid flow artifact and posterior displacement of the basilar artery findings raised the possibility of increased intracranial pressure. X-ray showed mild irregularity in the end plates of the lumbar vertebrae, bilateral coxa valga, irregularity in the articular surfaces of the ossified epiphysis of the upper and lower limbs, and generalized osteopenia. The audiological assessment profound hearing loss in both ears. Inborn error of metabolism, next-generation sequencing gene panel analysis, and whole exome sequencing showed that no pathogenic or likely pathogenic variants explaining the phenotypes. The single nucleotide polymorphisms testing showed a deletion in PEX6 gene (homozygous variant of uncertain significance). Conclusion: We report a case of ZS associated with a new PEX6 mutation that has not been previously reported in the literature. [JBCGenetics 2021; 4(2.000): 115-117

The phenotype, genotype, and outcome of infantile-onset Pompe disease in 18 Saudi patients

Infantile-Onset Pompe Disease (IOPD) is an autosomal recessive disorder of glycogen metabolism resulting from deficiency of the lysosomal hydrolase acid α-glucosidase encoded by GAA gene. Affected infants present before the age of 12 months with hypotonia, muscle weakness, and hypertrophic cardiomyopathy. Enzyme replacement therapy (ERT) has been shown to improve survival, cardiac mass, and motor skills. In this work, we aim to illustrate the genotypes of IOPD and the outcome of ERT in our population. The medical records of infants with confirmed diagnosis of IOPD who received ERT were reviewed. Eighteen infants (7 males, 11 females) were included in the study. The median age at presentation was 2 months and the median age at the start of ERT was 4.5 months. Fifteen (83.3%) infants died with a median age at death of 12 months. The 3 alive infants (whose current ages are 6½ years, 6 years, and 10 years), who were initiated on ERT at the age of 3 weeks, 5 months, and 8 months respectively, has had variable response with requirement of assisted ventilation in one child and tracheostomy in another child. All infants were homozygous for GAA mutations except one infant who was compound heterozygous. All infants (n = 8) with truncating mutations died. Our work provides insight into the correlation of genotypes and outcome of ERT in IOPD in Saudi Arabia. Our data suggest that early detection of cases, through newborn screening, and immunomodulation before the initiation of ERT may improve the outcome of ERT in Saudi infants with IOPD. Keywords: Pompe disease, Glycogen storage disease type II, Enzyme replacement therapy, GA