De novo heterozygous variants in KIF5B cause kyphomelic dysplasia.

Kyphomelic dysplasia is a heterogeneous group of skeletal dysplasias characterized by severe bowing of the limbs associated with other variable findings, such as narrow thorax and abnormal facies. We searched for the genetic etiology of this disorder. Four individuals diagnosed with kyphomelic dysplasia were enrolled. We performed whole-exome sequencing and evaluated the pathogenicity of the identified variants. All individuals had de novo heterozygous variants in KIF5B encoding kinesin-1 heavy chain: two with c.272A>G:p.(Lys91Arg), one with c.584C>A:p.(Thr195Lys), and the other with c.701G>T:p.(Gly234Val). All variants involved conserved amino acids in or close to the ATPase activity-related motifs in the catalytic motor domain of the KIF5B protein. All individuals had sharp angulation of the femora and humeri, distinctive facial features, and neonatal respiratory distress. Short stature was observed in three individuals. Three developed postnatal osteoporosis with subsequent fractures, two showed brachycephaly, and two were diagnosed with optic atrophy. Our findings suggest that heterozygous KIF5B deleterious variants cause a specific form of kyphomelic dysplasia. Furthermore, alterations in kinesins cause various symptoms known as kinesinopathies, and our findings also extend the phenotypic spectrum of kinesinopathies.

Perinatal factors contributing to chronic kidney disease in a cohort of Japanese children with very low birth weight.

BACKGROUND: Developmental programming of chronic kidney disease (CKD) in young adults is linked to preterm birth and intrauterine growth restriction (IUGR). Which confers a higher risk of progression to chronic kidney damage in children with very low birth weight (VLBW; born weighing < 1500 g): prematurity or IUGR? METHODS: This is a national historical cohort study of children with VLBW cared for in perinatal medical centers in Japan. Predictive factors included three latent variables (prematurity, IUGR, stress during neonatal period) and eight observed variables (gestational age, birth weight Z-score, maternal age, duration of treatment with antibiotics and diuretics, maternal smoking, late-onset circulatory collapse, kidney dysfunction) during the perinatal period. The primary endpoint was estimated glomerular filtration rate (eGFR) at age ≥ 3 years. A structural equation model was used to examine the pathologic constitution. RESULTS: The 446 children with VLBW included 253 boys and 193 girls, of mean age 5.8 ± 2.6 years and mean eGFR 111.7 ml/min/1.73 m2 at last encounter. Pathway analyses showed intrauterine malnutrition (ß = 0.85) contributed more to chronic kidney damage than stress during the neonatal period (ß = - 0.19) and prematurity (ß = 0.12), and kidney dysfunction and late-onset circulatory collapse were important observed variables in stress during the neonatal period. CONCLUSIONS: IUGR was more harmful to future kidneys of VLBW neonates. Neonatal kidney dysfunction and late-onset circulatory collapse were important risk factors for subsequent CKD development. This emphasizes the need for obstetricians to monitor for fetal growth restriction and neonatologists to minimize neonatal stress to prevent CKD in later life.

Antiviral therapy for hepatitis B virus during second pregnancies.

Mother-to-child transmission of the hepatitis B virus (HBV) is a major concern for infected mothers, especially after their first child has become an HBV carrier despite immunoprophylaxis. Eight mothers whose first child had become an HBV carrier despite immunoprophylaxis were referred for antiviral therapy during the subsequent pregnancy. All pregnant women were seropositive for both the hepatitis B surface antigen and hepatitis B e antigen. In the treatment group (three receiving lamivudine and two receiving tenofovir), mother-to-child transmission of the HBV was successfully prevented in all infants (5/5). On the other hand, two of three infants became HBV carriers in the untreated group. There were no significant adverse effects in either mothers or infants. Antiviral therapy using lamivudine and tenofovir during the second pregnancy successfully prevented mother-to-child transmission of the HBV for high-risk mothers.

Prognostic factors of hydrops fetalis with pleural effusion.

BACKGROUND: Hydrops fetalis (HF) has a low survival rate, particularly in the case of preterm birth. In addition, the severity index of HF has not been fully investigated yet. The aim of this study was to clarify the prognostic factors of HF with pleural effusion. METHODS: All live-born HF patients with pleural effusion, except for chromosomal abnormality or complex congenital heart disease, born from 2009 to 2013 in Aichi Prefecture in Japan were included. Prenatal, perinatal, and postnatal information was obtained from the medical records and was retrospectively analyzed. RESULTS: Forty-one HF patients with pleural effusion were included, and 28 patients (68%) survived. On multivariate logistic stepwise analysis, gestational birth week (OR, 0.71; 95% CI: 0.52-0.96, P = 0.027) and standard deviation (SD) score of the birthweight (OR, 1.74; 95% CI: 1.01-2.99, P = 0.045) were significant factors for postnatal death. All patients with both ≥32 gestational weeks and <3.0 birthweight SD score survived. CONCLUSIONS: Combined with the gestational weeks data, birthweight SD score may be useful to estimate the prognosis of HF with pleural effusion.

Novel SPEG variants in a neonate with severe dilated cardiomyopathy and relatively mild hypotonia.

Striated muscle preferentially expressed protein kinase (SPEG) variants have been reported to cause centronuclear myopathy associated with cardiac diseases. The severity of skeletal muscle symptoms and cardiac symptoms are presumably related to the location of the variant. Here, we report novel SPEG compound heterozygous pathological variants in a neonate with severe dilated cardiomyopathy and relatively mild hypotonia. This report expands the genotype-phenotype correlations of patients with SPEG variants.