Purpose: We investigated whether consecutive levels of new emerging renal biomarkers, including serum cystatin C (CysC) and urinary neutrophil gelatinase-associated lipocalin (NGAL)/creatinine (Cr) ratio, were affected by postconceptional age in very-low-birth-weight (VLBW) infants. Methods: Repeatedly measured samples for each infant were divided into four groups according to postnatal age: at birth (stage I), 3 to 7 days postnatally (stage II), 8 to 28 days postnatally (stage III), and >28 days postnatally (stage IV). The association between renal biomarkers and postconceptional age was assessed using Pearson's correlation coefficient, and the mean values of renal biomarkers in the four stages were compared using repeated-measures analysis of variance. Results: For samples measured at birth, serum CysC (r=-0.358, P=0.032) and urinary NGAL/Cr ratio (r=-0.522, P=0.001) were negatively correlated with gestational age, whereas serum Cr (r=0.148, P=0.390) was not. In addition, for all samples measured, serum CysC (r=-0.209, P=0.012), urinary NGAL/Cr ratio (r=-0.536, P<0.001), and serum Cr (r=-0.311, P<0.001) were negatively correlated with postconceptional age. Compared with the mean values of the postnatal age-specific stages, serum CysC showed no significant differences in any of the four stages. However, the urinary NGAL/Cr ratio in stage IV was significantly different from those in stages I to III. Conclusion: Although urinary NGAL/Cr ratio and serum CysC were negatively correlated with postconceptional age considering renal development, serum CysC showed no significant differences in any of the four postnatal age-specific stages. Urinary NGAL/Cr ratio at >28 days postnatally seems to be more affected by postconceptional age than serum CysC in VLBW infants.

Ectopic pancreas is defined as an abnormally located pancreatic tissue not sufficiently connected with the normal pancreas, which rarely occurs in neonates. To our knowledge, only a few cases of ectopic pancreas have been reported in newborns in South Korea. We report a case of ectopic pancreas as the cause of intussusception and jejunal atresia in a newborn. This clinical association is extremely rare, and this is the first report in South Korea.

We present the case of a healthy 28-day-old female full-term neonate who was admitted to the neonatal intensive care unit for severe metabolic acidosis, hypoglycemia, and an initial sinus rhythm. The first diagnostic hypothesis was hypovolemic shock, and fluid resuscitation was started immediately. During fluid therapy, cardiovascular collapse occurred with supraventricular tachycardia. The latter was successfully treated with adenosine and beta-blockers. After 8 days, electrocardiography showed ventricular pre-excitation, and Wolff-Parkinson-White syndrome was diagnosed. A novel variant of the MYL2 gene that is related to hypertrophic cardiomyopathy and conduction defect was found after discharge. Cardiogenic shock should be considered, despite being a rare cause of shock in neonates.

Treatment guidelines for postnatal cytomegalovirus (pCMV) infection in preterm have not been established yet. Neutropenia, thrombocytopenia, hepatitis, colitis, and sepsis-like disease are among the clinical manifestations, which range from moderate to serious. We present a case of autopsy diagnosed as pCMV infection in a premature infant delivered at gestational age of 24 weeks and 5 days. On the 7th and 14th days of birth, urinary CMV polymerase chain reaction samples were negative, ruling out congenital CMV infection. However, autopsy examination revealed that the patient had disseminated pCMV infection. CMV inclusion bodies were found in the majority of tissues, including the lung, liver, pancreas, breast, kidney, and adrenal gland, but not the placenta. The thymus exhibited significant cortical atrophy and T-cell immunodeficiency, possibly induced by dexamethasone treatment for bronchopulmonary dysplasia or by pCMV infection itself. If dexamethasone treatment is extended or high doses are considered, it may be beneficial to test the CMV infection status to prevent aggravation of infection. This case demonstrates that, despite the low prevalence, pCMV infection should be considered a differential diagnosis in preterm if other conditions or etiology cannot justify clinical deterioration.

Nemaline myopathy is a genetically heterogeneous neuromuscular disorder and one of the most common congenital myopathies. The clinical manifestations usually vary depending on the age of onset. Neonatal nemaline myopathy has the worst prognosis, primarily due to respiratory failure. Several genes associated with nemaline myopathy have been identified, including NEB, ACTA1, TPM3, TPM2, TNNT1, CFL2, KBTBD13, KLHL40, KLHL41, LMOD3, and KBTBD13. Here, we report a neonatal Korean female patient with nemaline myopathy carrying compound heterozygous mutations in the gene KLHL40 as revealed using next generation sequencing (NGS). The patient presented with postnatal cyanosis, respiratory failure, dysphagia, and hypotonia just after birth. To identify the genetic cause underlying the neonatal myopathy, NGS-based gene panel sequencing was performed. Compound heterozygous pathogenic variants were detected in KLHL40: c.[1405G>T];[1582G>A] (p. [Gly469cys];[Glu528Lys]). NGS allows quick and accurate diagnosis at a lower cost compared to traditional serial single gene sequencing, which is greatly advantageous in genetically heterogeneous disorders such as myopathies. Rapid diagnosis will facilitate efficient and timely genetic counseling, prediction of disease prognosis, and establishment of treatments.

Neonatal diabetes mellitus (NDM) is a rare disease that occurs at less than 6 months of age and is presumably caused by a mutation in the gene that affects pancreatic beta-cell function. Approximately 80% of NDM cases reveal a known genetic mutation, and mutations in potassium inwardly rectifying channel subfamily J member 11 (KCNJ11) and ABCC8 affecting the pancreatic beta-cell adenosine triphosphate-sensitive potassium channel may be treated with oral sulfonylurea. Early recognition of mutations in KCNJ11 and ABCC8 is important because early administration of sulfonylurea can not only control blood glucose levels but also improve neurodevelopmental outcomes. In the present study, we report a case of NDM that initially presented as diabetic ketoacidosis at the age of 1 month, accompanied by seizures during hospitalization. After confirmation of the KCNJ11 gene mutation (c.989A>C), we started administering oral sulfonylurea (glimepiride) at the age of 2 months. After gradually increasing the dosage of glimepiride, insulin was discontinued at the age of 3 months. To date, the infant's blood glucose levels have been well controlled without significant hypoglycemic events. No further episodes of seizures have occurred, and his developmental status is favorable.