Three cases of xanthinuria identified by gas chromatography/mass spectrometry-based urine metabolomics.

Introduction: Early diagnosis of patients with urolithiasis or hypouricemia owing to inborn errors of hypoxanthine metabolism is important in preventing renal failure or drug-induced toxicity. Case presentation: We identified three patients with xanthinuria using gas chromatography/mass spectrometry-based urine metabolomics: a 72-year-old male with bladder stone, a severe hypouricemic 59-year-old female with type 2 diabetes mellitus, and an 8-year and 9-month-old female who was first discovered to harbor a mutation in the xanthine dehydrogenase gene using whole-exome sequencing, but had a normal molybdenum cofactor sulfurase gene. Hydantoin-5-propionate was detected in the first and third patients but not in the second, suggesting that the first and second patients had type I and II xanthinuria, respectively. Conclusion: Gas chromatography/mass spectrometry-based metabolomics can be used for undiagnosed patients with xanthinuria, identification of the type of xanthinuria without allopurinol loading, and the quick functional evaluation of mutations in the xanthinuria-related genes.

Proteinuria and Renal Dysfunction Due to Extremely Low Birth Weight in a Patient with Silver-Russell Syndrome.

A 36-year-old woman diagnosed with Silver-Russell syndrome during childhood presented to our department after a primary care physician suspected renal dysfunction. At birth, she had an extremely low weight (1210 g), and in childhood, she was diagnosed with Silver-Russell syndrome. At the age of 14 she was found to have proteinuria; however, the condition was never further examined. One month prior to her presentation to our department, the following were noted: 3+ urinary protein, 3.9 urinary protein/creatinine ratio, and 48 mL/min/1.73 m2 estimated glomerular filtration rate. Abdominal computed tomography revealed small kidneys difficult to visualize using ultrasound. Therefore, an open renal biopsy was performed. The renal biopsy revealed no significant findings in the glomerulus except glomerular hypertrophy, and the glomerular density in the cortical area was low (0.6/mm2). The patient was diagnosed with oligomeganephronia. Proteinuria and renal dysfunction were likely due to glomerular hyperfiltration resulting from a low nephron count caused by low birth weight. Silver-Russell syndrome is characterized by intrauterine growth retardation and additional developmental disorders after birth. Here, we detected oligomeganephronia following kidney biopsy in a patient with Silver-Russell syndrome. We suspect that a reduced number of nephrons due to low birth weight caused proteinuria and renal dysfunction.

Recessive NUP54 Variants Underlie Early-Onset Dystonia with Striatal Lesions.

Infantile striatonigral degeneration is caused by a homozygous variant of the nuclear-pore complex (NPC) gene NUP62, involved in nucleo-cytoplasmic trafficking. By querying sequencing-datasets of patients with dystonia and/or Leigh(-like) syndromes, we identified 3 unrelated individuals with biallelic variants in NUP54. All variants clustered in the C-terminal protein region that interacts with NUP62. Associated phenotypes were similar to those of NUP62-related disease, including early-onset dystonia with dysphagia, choreoathetosis, and T2-hyperintense lesions in striatum. In silico and protein-biochemical studies gave further evidence for the argument that the variants were pathogenic. We expand the spectrum of NPC component-associated dystonic conditions with localized basal-ganglia abnormalities. ANN NEUROL 2023;93:330-335.

Biallelic pathogenic variants in roundabout guidance receptor 1 associate with syndromic congenital anomalies of the kidney and urinary tract.

Congenital anomalies of the kidney and urinary tract (CAKUT) represent the most common cause of chronic kidney failure in children. Despite growing knowledge of the genetic causes of CAKUT, the majority of cases remain etiologically unsolved. Genetic alterations in roundabout guidance receptor 1 (ROBO1) have been associated with neuronal and cardiac developmental defects in living individuals. Although Slit-Robo signaling is pivotal for kidney development, diagnostic ROBO1 variants have not been reported in viable CAKUT to date. By next-generation-sequencing methods, we identified six unrelated individuals and two non-viable fetuses with biallelic truncating or combined missense and truncating variants in ROBO1. Kidney and genitourinary manifestation included unilateral or bilateral kidney agenesis, vesicoureteral junction obstruction, vesicoureteral reflux, posterior urethral valve, genital malformation, and increased kidney echogenicity. Further clinical characteristics were remarkably heterogeneous, including neurodevelopmental defects, intellectual impairment, cerebral malformations, eye anomalies, and cardiac defects. By in silico analysis, we determined the functional significance of identified missense variants and observed absence of kidney ROBO1 expression in both human and murine mutant tissues. While its expression in multiple tissues may explain heterogeneous organ involvement, variability of the kidney disease suggests gene dosage effects due to a combination of null alleles with mild hypomorphic alleles. Thus, comprehensive genetic analysis in CAKUT should include ROBO1 as a new cause of recessively inherited disease. Hence, in patients with already established ROBO1-associated cardiac or neuronal disorders, screening for kidney involvement is indicated.

Ischemic colitis in an infant with constipation treated with stimulant laxative.

Ischemic colitis (IC), the most common form of intestinal ischemia, ranges from superficial mucosal and submucosal injury to full-thickness mural necrosis. As risk factors include cerebrovascular disease, hypertension, diabetes mellitus, prior abdominal surgery, irritable bowel syndrome, and constipation, IC typically occurs in elderly persons with multiple comorbidities rather than young children. A 1-year-old Japanese girl receiving a stimulant laxative for constipation since age 7 months was hospitalized for fever, vomiting, and hypovolemic shock. Her abdomen was swollen, and abdominal computed tomography showed colonic distension with abundant stool. Colonic decompression and intensive care brought about rapid improvement until persistent bloody diarrhea that commenced on day 17 of illness required transfer to another hospital, where colonoscopy on day 42 showed mucosal sloughing forming pseudomembranes, as well as focal stenosis. Contrast enema on day 45 confirmed stenosis with a "thumbprint" contour at the splenic flexure. Diagnosed with IC, she received parenteral nutrition and an elemental diet. Bloody diarrhea resolved by day 75. Colonoscopy and contrast enema on day 110 showed normal mucosa and resolution of stenosis. We believe that IC arose from constipation and stimulant laxative treatment and consider this to be the first report of infantile IC complicating constipation.

A homozygous splice site ROBO1 mutation in a patient with a novel syndrome with combined pituitary hormone deficiency.

The genetic causes of combined pituitary hormone deficiency remain elusive in most patients. Recently, incompletely penetrant heterozygous mutations in ROBO1 have been described in patients with pituitary stalk interruption syndrome. Herein, we identified a novel homozygous slice site mutation in ROBO1 (c.1342+1G>A) using a trio whole-exome sequencing strategy in a 5-year-old Japanese boy who had combined pituitary hormone deficiency, psychomotor developmental delay, severe intellectual disability, sensorineural hearing loss, strabismus, and characteristic facial features, including a broad forehead, micrognathia, and arched eyebrows. Magnetic resonance imaging delineated anterior pituitary hypoplasia, ectopic posterior pituitary, invisible pituitary stalk, thinning of the corpus callosum, and hypoplasia of the pons and midbrain. The phenotypically normal parents (first cousins) were heterozygous for the mutation. The results provide further evidence of ROBO1 being involved in the development of the pituitary gland. A recessive mutation of ROBO1 is a potential novel cause of a syndromic disorder associated with combined pituitary hormone deficiency.

Hematopoietic stem cell transplantation for progressive combined immunodeficiency and lymphoproliferation in patients with activated phosphatidylinositol-3-OH kinase δ syndrome type 1.

BACKGROUND: Activated phosphatidylinositol-3-OH kinase δ syndrome type 1 (APDS1) is a recently described primary immunodeficiency syndrome characterized by recurrent respiratory tract infections, lymphoid hyperplasia, and Herpesviridae infections caused by germline gain-of-function mutations of PIK3CD. Hematopoietic stem cell transplantation (HSCT) can be considered to ameliorate progressive immunodeficiency and associated malignancy, but appropriate indications, methods, and outcomes of HSCT for APDS1 remain undefined. OBJECTIVE: Our objective was to analyze the clinical manifestations, laboratory findings, prognosis, and treatment of APDS1 and explore appropriate indications and methods of HSCT. METHODS: We reviewed retrospectively the medical records of cohorts undergoing HSCT at collaborating facilities. RESULTS: Thirty-year overall survival was 86.1%, but event-free survival was 39.6%. Life-threatening events, such as severe infections or lymphoproliferation, were frequent in childhood and adolescence and were common indications for HSCT. Nine patients underwent HSCT with fludarabine-based reduced-intensity conditioning. Seven patients survived after frequent adverse complications and engraftment failure. Most symptoms improved after HSCT. CONCLUSION: Patients with APDS1 showed variable clinical manifestations. Life-threatening progressive combined immunodeficiency and massive lymphoproliferation were common indications for HSCT. Fludarabine-based reduced-intensity conditioning-HSCT ameliorated clinical symptoms, but transplantation-related complications were frequent, including graft failure.

A novel heterozygous GLI2 mutation in a patient with congenital urethral stricture and renal hypoplasia/dysplasia leading to end-stage renal failure.

Glioblastoma 2 (GLI2) is a mediator of Sonic hedgehog signaling pathway that plays an important role in development of the central nervous system and limbs. Heterozygous GLI2 mutations have been associated with postaxial polydactyly, various pituitary dysfunction, and holoprosencephaly-like phenotype. Herein, we report a Japanese boy who presented with isolated growth hormone deficiency with ectopic posterior pituitary, postaxial polydactyly, atrioventricular septal defect, intellectual disability and dysmorphic facial features including mid-facial hypoplasia. The patient was also complicated with congenital urethral stricture with megacystis, hydronephrosis, and renal hypoplasia/dysplasia, which led to end-stage renal failure by the age of 8 years. Trio-whole-exome sequencing showed a novel de novo heterozygous frameshift mutation in GLI2 (c.3369delG, p.Met1123Ilefs*7) in the patient. This is the first report of possible association between GLI2 mutation and the phenotype of congenital anomalies of the kidney and urinary tract, and subsequent end-stage renal failure. Further studies on the urogenital phenotype in patients with GLI2 mutations may clarify a role of GLI2 in embryonic development of the urinary tract.

A neonatal case of Japanese spotted fever.

We herein present the case of a 28-day-old female with Japanese spotted fever, who is the youngest reported patient so far. Tick-borne diseases, including Japanese spotted fever, should be included in the differential diagnosis of eruptive fever even in neonates because a treatment delay can lead to a fatal outcome.

Lack of an association between E-selectin gene polymorphisms and risk of Kawasaki disease.

BACKGROUND: Coronary artery lesions (CAL) are a serious complication of Kawasaki disease (KD). The increased serum E-selectin level during the acute phase of KD and the association of E-selectin gene (SELE) polymorphisms with the prevalence of coronary artery disease in adults suggest a possible association between SELE polymorphisms and the development of CAL in KD patients. METHODS: The subjects consisted of 177 KD patients, including 59 with and 118 without CAL, and 305 healthy controls. Two single nucleotide polymorphisms (SNP) of SELE, 98G>T (rs1805193) and Ser128Arg (rs5361), were genotyped by direct sequencing and the high-resolution melting curve method, respectively. The allele distributions were assessed using the chi-squared test. RESULTS: There were no significant differences in the T allele frequency at 98G>T between KD patients and controls (1.4% vs 1.0%, P = 0.55) or between KD patients with and without CAL (1.7% vs 1.3%, P = 0.77). Similarly, there were no differences in the distribution of the C allele (128Arg) at Ser128Arg between KD patients and controls (4.5% vs 3.4%, P = 0.40) or between KD patients with and without CAL (4.2% vs 4.7%, P = 0.86). CONCLUSION: Although no association was detected between these SELE polymorphisms and the prevalence of KD or the development of CAL, this may have been due to the study limitations, including a low frequency of the minor alleles and a small sample size. A larger-scale association study is needed in order for a definitive conclusion to be made as to whether these SNP are associated with susceptibility to KD or not.