Variants in TCF20 in neurodevelopmental disability: description of 27 new patients and review of literature

Purpose:

To define the clinical characteristics of patients with variants in TCF20, we describe 27 patients, 26 of whom were identified via exome sequencing. We compare detailed clinical data with 17 previously reported patients.

Methods:

Patients were ascertained through molecular testing laboratories performing exome sequencing (and other testing) with orthogonal confirmation; collaborating referring clinicians provided detailed clinical information.

Results:

The cohort of 27 patients all had novel variants, and ranged in age from two to 68 years. All had developmental delay/intellectual disability. Autism spectrum disorders/autistic features were reported in 69%, attention disorders or hyperactivity in 67%, craniofacial features (no recognizable facial gestalt) in 67%, structural brain anomalies in 24%, and seizures in 12%. Additional features affecting various organ systems were described in 93%. In a majority of patients, we did not observe previously reported findings of postnatal overgrowth or craniosynostosis, in comparison to earlier reports.

Conclusion:

We provide valuable data regarding the prognosis and clinical manifestations of patients with variants in TCF20.

Intrauterine growth retardation: altered hepatic energy and redox states in the fetal rat

We determined the extent to which ligating both maternal uterine arteries affects fetal hepatic energy and redox states in the fetal rat. Bilateral maternal uterine artery ligation on d 18 of the rat's 21.5-d gestation significantly inhibits fetal growth; sham surgery limits growth to a lesser extent. Within 12 h of surgery and persisting to d 19, small-for-gestational age (SGA) fetuses had significantly diminished ATP/ADP and adenylate charge ratios, whereas sham fetuses had values intermediate between SGA and normal. Hepatic mitochondrial redox state demonstrated similar changes. Cytosolic redox state in SGA fetuses at 12 and 24 h after surgery was significantly elevated. SGA fetuses had significantly diminished plasma insulin and elevated glucagon concentrations. On d 19 and 20, hepatic ATP/ADP and cytosolic NAD+/NADH correlated directly for sham and normal but not SGA fetuses. Alterations in glucose, insulin, and glucagon availability and hypoxia were responsible for the changes in energy and redox states. They may also have disassociated hepatic cytosolic from mitochondrial redox states and altered the equilibrium between adenine and nicotinamide nucleotides. These altered cellular functions retarded fetal growth. Newborn SGA, sham, and normal rat pups had similar hepatic ATP/ADP, cytosolic, and mitochondrial redox states at 10 and 240 min after delivery suggesting that the hypoglycemia which developed in SGA pups was not attributable to alterations in these variables.

Human placental lactogen administration in the pregnant rat: acceleration of fetal growth

To determine whether administration of human placental lactogen (hPL) to pregnant rats during late gestation might enhance fetal growth, we implanted osmotically driven minipumps to provide 75 micrograms h PL/24 h on day 14 of the rat's 21.5-day gestation. This substantially increased maternal and fetal plasma hPL concentrations. By day 18, hPL fetuses were significantly heavier and had larger placentas than controls. From this point until term, their rate of growth (1.20 g/24 h) significantly exceeded that of controls (0.95 g/24 h). Birth weights differed significantly (hPL 5.86 +/- 0.08 g; controls 5.20 +/- 0.08 g, p less than 0.001). This increase was due primarily to significant increases in the growth of the liver and carcass. Enhanced glucose availability was in part responsible for this phenomenon inasmuch as plasma glucose concentrations were significantly increased in hPL maternal rats from days 15 to 19. This resulted on days 18 and 19 in significantly increased plasma glucose and insulin concentrations in hPL fetuses. Fetal/maternal glucose ratios did not differ between hPL and control fetuses. Fetal heptic glycogen concentrations were significantly increased on day 18 and 19 but were similar to controls from day 20 until birth. These observations suggest that increased maternal glucose availability with consequent stimulation of fetal insulin secretion accelerated the growth of hPL fetuses. However, maternal and fetal plasma glucose concentrations and fetal plasma insulin and hepatic glycogen concentrations on days 20 and 21 were normal, suggesting that other factors also were responsible for sustaining the accelerated fetal growth on these days.(ABSTRACT TRUNCATED AT 250 WORDS)

Selective ligation of uterine artery branches accelerates fetal growth in the rat

We determined if reducing litter number by selective fetal ablation (A) might enhance the growth of the surviving fetuses. On day 14 of the rat's 21.5-day gestation, we ligated branches of the uterine artery at their secondary division. Each of these branches supplies a placenta and its fetus, and ligation kills them. Every other fetus in litters of eight to 14 fetuses was ablated. Each A maternal rat was matched to a control with an equal number of fetuses. Ablation reduced fetal number (from 8-14 to 4-7) and increased fetal growth (birth weight 5.84 +/- 0.05 versus 5.20 +/- 0.05 g, p less than 0.001). In the A but not control litters, newborn body mass was negatively related to litter number. Fetuses of A litters had increased carcass, liver, and brain mass. On days 18 and 19, fetal plasma glucose concentrations, fetal/maternal glucose ratios, insulin concentrations, and hepatic glycogen concentrations were increased suggesting that A increases glucose provision to the surviving fetuses. Although these observations imply that A enhances glucose provision resulting in stimulated growth of insulin-sensitive tissues, the growth of the brain, purportedly a tissue not sensitive to insulin, was also increased. In addition, the growth rate of A fetuses continued to be increased on days 20 and 21 despite normal fetal plasma glucose and insulin. These observations indicate that with A, factors other than insulin also stimulated growth. Of note, newborn A pups developed hypoglycemia at 20 and 60 min as a result of increased insulin secretion.

Intravenous lipid and amino acids briskly increase plasma glucose concentrations in small premature infants

We determined the glycemic response to intravenous lipid infusion alone, lipid with amino acids, or amino acids alone in 15 very small premature infants receiving constant glucose infusion during early life. Infants who received lipid or lipid and amino acids demonstrated significant increases in glucose compared with infants who received amino acids. The combination of lipid and amino acids resulted in an earlier increase than lipid alone. Although plasma insulin did not change in all three groups, infants who received amino acids alone demonstrated an appropriate increase in glucagon. These data suggest that lipid infusion, a commonly used means of providing nutrition to premature infants, may cause significant disturbances in glucoregulation, particularly when administered with amino acids.

Limited maternal fuel availability due to hyperinsulinemia retards fetal growth and development in the rat

We rendered pregnant rats chronically hyperinsulinemic to determine the effect of reduced maternal metabolic fuel availability on fetal growth and development. We implanted osmotically driven insulin loaded minipumps on day 14 (term 21.5 days) in pregnant rats. This significantly increased maternal plasma concentrations of insulin and reduced glucose from day 15 until term. From day 17 until birth, fetal growth was significantly less for hyperinsulinemic mothers (term birth weight 4.53 +/- 0.07 versus 5.64 +/- 0.06 g, p less than 0.001). In fetuses of hyperinsulinemic mothers plasma glucose and insulin concentrations were significantly reduced while glucagon concentrations were increased. Total plasma amino acids were significantly reduced in maternal rats and their fetuses from days 17 to 19 while arteriovenous blood gas tensions and pH did not differ between fetuses of hyperinsulinemic and control mothers. Small for gestational age newborn pups of hyperinsulinemic mothers were hypoglycemic for the first 240 min of life as a result of limited hepatic glycogen stores and a delay in the normally expected induction of hepatic cytosolic phosphoenolpyruvate carboxykinase. This occurred despite significant increases in neonatal plasma glucagon concentrations. These data indicate that limitation of maternal glucose and amino acids with normal placental gaseous exchange retards fetal growth, limits hepatic glycogen deposition, and delays neonatal phosphoenolpyruvate carboxykinase induction. Limited fetal insulin secretion resulting from diminished maternal fuel availability may have also been a factor in retarding growth. The delay in phosphoenolpyruvate carboxykinase induction despite enhanced glucagon secretion during fetal and neonatal life suggests a specific "resistance" to this hormone in the rat growth retarded by limited metabolic fuel availability.