In pregnancy, complex alterations occur in lipid metabolism. Percent change in TG is affected positively by the nutrition level. The neonatal weight also increases as well but postnatal weight is unaffected. Conversely TG levels significantly decrease in preterm birth. No association between preeclampsia and gestational diabetes mellitus with lipid profile changes were noted except in patients with glucose intolerance (>140 mg/dl in 50 g screening test) in which change in cholesterol, LDL was low and TG was high.
BACKGROUND
Knobloch syndrome is a rare, autosomal recessive, developmental disorder characterized by stereotyped ocular abnormalities with or without occipital skull deformities (encephalocele, bone defects, cutis aplasia). Although there is clear heterogeneity in clinical presentation, central nervous system malformations, aside from the characteristic encephalocele, have not typically been considered a component of the disease phenotype.
METHODS
Four patients originally presented for genetic evaluation of symptomatic structural brain malformations. Whole-genome genotyping, whole-exome sequencing, and confirmatory Sanger sequencing were performed. Using immunohistochemical analysis, we investigated the protein expression pattern of COL18A1 in the mid-fetal and adult human cerebral cortex and then analyzed the spatial and temporal changes in the expression pattern of COL18A1 during human cortical development using the Human Brain Transcriptome database.
RESULTS
We identified two novel homozygous deleterious frame-shift mutations in the COL18A1 gene. Upon further investigation of these patients and their families, we found that many exhibited certain characteristics of Knobloch syndrome, including pronounced ocular defects. Our data strongly support an important role for COL18A1 in brain development and this report contributes to an enhanced characterization of the brain malformations that can result from deficiencies of collagen XVIII.
CONCLUSIONS
This case series highlights the diagnostic power and clinical utility of whole-exome sequencing technology – allowing clinicians and physician scientists to better understand the pathophysiology and presentations of rare diseases. We suggest that patients who are clinically diagnosed with Knobloch syndrome and/or found to have COL18A1 mutations via genetic screening should be investigated for potential structural brain abnormalities even in the absence of encephaloceles.
Homozygous mutations in the fibroblast growth factor 3 (FGF3) gene have recently been discovered in an autosomal recessive form of syndromic deafness characterized by complete labyrinthine aplasia (Michel aplasia), microtia, and microdontia (OMIM 610706 - LAMM). In order to better characterize the phenotypic spectrum associated with FGF3 mutations, we sequenced the FGF3 gene in 10 unrelated families in which probands had congenital deafness associated with various inner ear anomalies, including Michel aplasia, with or without tooth or external ear anomalies. FGF3 sequence changes were not found in eight unrelated probands with isolated inner ear anomalies or with a cochlear malformation along with auricle and tooth anomalies. We identified two new homozygous FGF3 mutations, p.Leu6Pro (c.17T>C) and p. Ile85MetfsX15 (c.254delT), in four subjects from two unrelated families with LAMM. The p.Leu6Pro mutation occurred within the signal site of FGF3 and is predicted to impair its secretion. The c.254delT mutation results in truncation of FGF3. Both mutations completely co-segregated with the phenotype, and heterozygotes did not have any of the phenotypic findings of LAMM. Some affected children had large skin tags on the upper side of the auricles, which is a distinctive clinical component of the syndrome. Enlarged collateral emissary veins associated with stenosis of the jugular foramen were noted on computerized tomographies of most affected subjects with FGF3 mutations. However, similar venous anomalies were also detected in persons with non-syndromic Michel aplasia, suggesting that a direct causative role of impaired FGF3 signaling is unlikely.
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