Clinical features and genetic analysis of a child with 3-methylglutenedioic aciduria type VII due to novel variants of CLPB gene / 中华医学遗传学杂志

OBJECTIVE@#To explore the clinical features and genetic basis for a child with 3-methylglutaconic aciduria type VII.@*METHODS@#A child who was diagnosed at the Gansu Provincial Maternity and Child Health Care Hospital on August 9, 2019 was selected as the study subject. Clinical data of the child, including urine gas chromatography and mass spectrometry, were collected. The child and her parents were subjected to whole exome sequencing.@*RESULTS@#The child, a female neonate, had presented mainly with intermittent skin cyanosis, convulsions, hypomagnesemia, apnea, neutropenia after birth. Her urine 3-methylpentenedioic acid has increased to 17.53 μmol/L. DNA sequencing revealed that she has harbored compound heterozygous variants of the CLPB gene, namely c.1016delT (p.L339Rfs*5) and c.1087A>G (p.R363G), which were respectively inherited from her mother and father. Both variants were unreported previously. Based on the standards from the American College of Medical Genetics and Genomics (ACMG), the variants were respectively predicted to be pathogenic and likely pathogenic.@*CONCLUSION@#The child was diagnosed with 3-methylglutenedioic aciduria type VII. Discovery of the c.1016delT and c.1087A>G variants has enriched the mutational spectrum of the CLPB gene.

Neutropenia congénita de tipo IV: reporte de un caso / Congenital neutropenia type IV: case report

La neutropenia congénita grave (NCG) es una entidad heterogénea cuya característica común es un recuento absoluto de neutrófilos inferior a 0,5 x 10 9/l. Presenta gran heterogeneidad genética, las mutaciones más frecuentes son las del gen de la elastasa 2 (ELA 2). El tratamiento de primera elección es la administración de factor estimulador de colonias de granulocitos. Los pacientes con NCG presentan infecciones graves en etapas tempranas de la vida. Se presenta una paciente con NCG asociada a fenotipo peculiar con facies triangular, retromicrognatia, patrón venoso prominente en miembros inferiores, comunicación interauricular y mal progreso ponderal, en quien se diagnosticó déficit de la enzima glucosa 6 fosfato deshidrogenasa, subunidad catalítica 3 (G6PC3). A pesar de lo infrecuente de esta mutación como causa de NCG (2 %), su conocimiento cobra importancia porque la coexistencia del fenotipo característico con una NCG orienta en la solicitud del estudio genético que permite arribar al diagnóstico.

Severe congenital neutropenia (SCN) is a heterogeneous disease whose more common feature is an absolute neutrophil count less than 0.5 x 10 9/l. It presents great genetic heterogeneity. Autosomal dominant inherited mutations of the elastase 2 gene (ELA2) represent the most common etiology. The first choice treatment is the administration of granulocyte colony stimulating factor. Patients with SCN develop severe infections early in life. We present a patient who associated SCN to a peculiar phenotype, characterized by triangular facies, retromicrognathia, prominent venous pattern in the lower limbs, atrial septal defect and poor weight progress, in whom a deficiency of the enzyme glucose 6 phosphate dehydrogenase, a catalytic subunit 3 (G6PC3), was diagnosed. Despite the infrequency of this mutation as the origin of SCN (2%), its knowledge becomes important because the coexistence of the characteristic phenotype and SCN guides the request for the genetic study that allows reaching the diagnosis.

Clinical and genetic analysis of four patients with congenital neutropenia / 中华医学遗传学杂志

OBJECTIVE@#To delineate the clinical feature and genetic basis of four patients with congenital neutropenia.@*METHODS@#All patients were subjected to whole exome sequencing (WES). Suspected variants were verified by Sanger sequencing.@*RESULTS@#The patients (two boys and two girls), aged 7 to 15 months, suffered from neutropenia and recurrent infections. Bone marrow smears showed a significant decrease in the proportion of rod-shaped and lobulated granulocytes, which suggested impaired development and maturation of bone marrow neutrophils. WES has discovered heterozygous variants (c.496G>A, c.58C>G, c.391G>A and IVS1+5T>A) of the ELANE gene in the patients. Among these, c.58C>G and IVS1+5T>A were unreported previously. Follow up revealed patients 1 and 3 had periodic neutropenia, while patients 2 and 4 had severe congenital neutropenia. After attaining the definite diagnosis, the patients were treated symptomatically.@*CONCLUSION@#The main clinical feature of congenital neutropenia is refractory recurrent bacterial infections, for which mutations of the ELANE gene are a common cause. Two novel pathogenic ELANE variants have been discovered in this study.

A Case of Shwachman-Diamond Syndrome Confirmed with Genetic Analysis in a Korean Child

Shwachman-Diamond syndrome (SDS) is an autosomal recessive genetic disorder, consisting of exocrine pancreatic insufficiency, chronic neutropenia, neutrophil chemotaxis defects, metaphyseal dysostosis, short stature, dental caries, and multiple organ involvements. Although SDS is the second most common hereditary abnormality of exocrine pancreas following cystic fibrosis in the Western countries, it has rarely been reported in Asia. We diagnosed a case of SDS in a 42-month-old girl, and genetic analysis including the relatives of the patient confirmed the diagnosis for the first time in Korea. She had short stature, steatorrhea, dental caries, and recurrent prulent otitis media and pneumonias. Laboratory studies revealed cyclic neutropenia, and serum levels of trypsin, amylase, and lipase were decreased. Simple radiography revealed metaphyseal sclerotic changes at the distal femur. A CT scan demonstrated a fatty infiltration and atrophy of the pancreas. On direct sequencing analysis of Shwachman-Bodian-Diamond Syndrome gene exon 2 region, the patient was homozygous for the c.258+2T>C mutation and heterozygous for the c.183_184TA>CT mutation and c.201A>G single nucleotide polymorphism. Treatment with pancreatic enzyme replacement, multivitamin supplementation, and regular to high fat diet improved her weight gain and steatorrhea.

Una variedad genética de la UDP-glucuronosil transferasa asociada a toxicidad gastrointestinal por irinotecan / A prevalent genetic variety of UDP-glycuronosyl transferase predicts high risk of irinotecan toxicity

Los avances en genética y biología molecular han impulsado la aparición de nuevas áreas de estudio en la medicina, como la farmacogenómica, la cual intenta predecir la respuesta y toxicidad a drogas en función de la variabilidad genética de cada individuo, constituyendo los llamados síndromes fármacogenómicos. La oncología podría beneficiarse debido a la gran toxicidad de sus fármacos. Hay varios loci genéticos que se están analizando por su potencial valor predictivo y hasta ahora sólo tres de ellos demostraron cierto grado de utilidad clínica. En especial, el estudio del número de repeticiones del dinucleótido timina-adenina (TA) en el promotor de la enzima UDP-glucuronosil-transferasa (UGT) mostró ser capaz de predecir neutropenia severa en pacientes expuestos a dosis intermedias y altas de irinotecan. Comunicamos el caso de una paciente con cáncer de pulmón de células pequeñas que padeció toxicidad hematológica y gastrointestinal grave tras haber sido tratada con dosis relativamente bajas (65 mg/m2) de irinotecan, y en quien un análisis del ADN leucocitario mostró la presencia de homocigosis para siete repeticiones de TA. Este caso es un ejemplo de aplicabilidad clínica del test, se discute su utilidad como predictor de toxicidad y la conducta a tomar frente a pacientes con estas características.

The advances in genetics and molecular biology have raised new areas in medicine, such as pharmacogenomics, which tries to predict drug responses and toxicities based on the individual genetic variability, describing the so called: pharmacogenomic syndromes. Oncology would find this development extremely useful because of the severe toxicity of chemotherapy. There are a lot of genetic loci under investigation for their potential in predicting drug toxicity, but only three of them have showed clinical usefulness up to now. In particular, quantification of the number of thymine-adenine (TA) dinucleotics in the promoter region of the UDP-glucuronosyl-transferase 1A1 enzime (TA indel) proved to be capable of predicting severe neutropenia in patients exposed to intermediate or high doses of irinotecan. Herein we report a case of a patient with small cell lung cancer who suffered severe hematological and gastrointestinal toxicity after being treated with relatively low doses (65 mg/m2) of irinotecan and whose leucocyte DNA analysis showed the presence of seven TA repetitions in both alleles. This case is an example of the clinical applicability and the utility of the test as a toxicity predictor. We also discuss the clinical decisions that may be taken with these patients.