Nonketotic hyperglycinemia case series

Abstract

To present three cases who presented with neonatal hiccups and who were later diagnosed with nonketotic hyperglycinemia (NKH). Case series. We present three babies who presented in neonatal life with hiccups who later were diagnosed with NKH. Two babies presented on the 2nd day of life with hypotonia, poor feeding, and abnormal movements including jitteriness, hiccups, and twitching. The third baby only had transient hiccups lasting for a couple of days in the 1st week of life but later presented at 3 months of age with poor feeding, drowsiness, and jerky movements. All three cases needed extensive investigations before reaching the diagnosis including metabolic screen, lumbar puncture, electroencephalography, and computed tomography/magnetic resonance imaging. The first two babies needed intubation on their 2nd day of life because of apneas in whom later, the care was withdrawn after reaching the diagnosis of NKH because of poor prognosis. The third baby was discharged home on oral dextromethorphan and ketogenic diet. We discuss the importance of early recognition of symptoms (frequent hiccups) and investigation needed to reach the diagnosis early as it helps in making decision to either carry on treatment or withdraw care because of poor prognosis. It also helps in genetic counseling and prenatal diagnosis can be offered at the subsequent pregnancy.

Inborn Errors of Metabolism and Epilepsy: Current Understanding, Diagnosis, and Treatment Approaches

“…Characteristically EEG recordings show a burst suppression pattern which later evolves to hypsarrhythmia and multifocal epilepsy [ 44 ]. On magnetic resonance imaging (MRI), with a classic newborn presentation, infants show increased signal on diffusion weighted images in the areas that are myelinated at birth, most often in the posterior limb of the internal capsule [ 45 ]. Hypoplasia or agenesis of the corpus callosum has also been reported.…”

The Mutation Analysis of the AMT Gene in a Chinese Family With Nonketotic Hyperglycinemia

“…The use of low-dose strychnine nitrate and exchange blood therapy can reduce the blood glycine content, but these treatments have caused brain damage and further preventive treatments are invalid ( von Wendt et al, 1980 ). Therefore, treatment is focused on reducing plasma glycine concentration by initiating sodium benzoate and utilizing N-methyl-D-aspartate receptor site antagonists (i.e., dextromethorphan and oral ketamine) to reduce glycinergic stimulation ( Van Hove et al, 2005 ; Prasad et al, 2015 ). This therapy has been shown to be effective in controlling seizures and neurodevelopment in selected nonketotic hyperglycinemic populations ( Bjoraker et al, 2016 ).…”

Hiperglicinemia no cetósica neonatal, fenotipo atenuado

“…Debe tenerse presente que la elevación de la glicina en LCR es más importante que la relación, que es solo una medida secundaria y los hallazgos metabólicos hacen, en la práctica, el diagnóstico definitivo en nuestro medio, dada la dificultad en el estudio molecular y enzimático (5). Se espera que el perfil de ácidos orgánicos en la orina sea normal, sin presentar grandes desarreglos en estudio metabólico (2). Pequeñas elevaciones de múltiples ésteres de acilglicina se han reportado ocasionalmente (7).…”

“…En las series reportadas, un alto porcentaje >75% presenta el patrón de estallido supresión en el EEG, que si bien no es específico, es sugestivo de esta condición (5).En neuroimágenes se reportan la espongiosis generalizada de los tractos ascendentes descendentes de sustancia blanca como los principales rasgos histopatológicos de HNC neonatal (10). En una serie de 24 pacientes de presentación neonatal se encontró restricción a la difusión en todos ellos en brazo posterior de cápsula interna, tallo en su porción anterior, tractos del tegmento posterior y cerebelo, además de hipoplasia del cuerpo calloso (11); y en otros estudios, hipoplasia vermiana y megacisterna magna (2). Estos hallazgos son consistentes en diferentes series y se presentaron en este caso también.…”

“…La Hiperglicinemia no Cetósica (HNC) es un error innato del metabolismo de herencia autosómica recesiva, cuya principal característica es la acumulación de glicina en los fluidos corporales, producido por una falla en el complejo de clivaje enzimático de este aminoácido (1,2). La glicina es un aminoácido no esencial (1) con acción dual como neurotransmisor excitador e inhibidor.…”