Clinical, neuroradiological, and molecular characterization of mitochondrial threonyl-tRNA-synthetase (TARS2)-related disorder.

Purpose: Biallelic variants in TARS2, encoding the mitochondrial threonyl-tRNA-synthetase, have been reported in a small group of individuals displaying a neurodevelopmental phenotype but with limited neuroradiological data and insufficient evidence for causality of the variants.

Methods: Exome or genome sequencing was carried out in 15 families. Clinical and neuroradiological evaluation was performed for all affected individuals, including review of 10 previously reported individuals.

Bowen-Conradi: a common Hutterite condition that mimics trisomy 18.

Bowen-Conradi syndrome (BCS) is a lethal autosomal recessive condition having significant clinical overlap with trisomy 18. Though rare in the general population, it is quite common in the Hutterites of the United States and Canada. The carrier frequency in the Hutterite population is estimated to be one in 10, making BCS one of the most commonly inherited genetic diseases in any human group studied to date.

Clinical course of a 20-month-old child diagnosed prenatally with mosaic ring chromosome 18 and monosomy 18.

We report on a 20-month-old male, diagnosed prenatally with de novo mosaic ring chromosome 18 and low level monosomy 18, who also exhibited an inherited and apparently balanced translocation between chromosomes 3 and 6. We believe this to be the first reported case of prenatally diagnosed mosaic ring chromosome 18 and monosomy 18 in which the child was carried to term. Ring chromosomes are associated with an abnormal phenotype that is dependent on the amount of material that is deleted from the p and q arms.

Development of a newborn screening follow-up algorithm for the diagnosis of isobutyryl-CoA dehydrogenase deficiency.

Purpose: Isobutyryl-CoA dehydrogenase deficiency is a defect in valine metabolism and was first reported in a child with cardiomyopathy, anemia, and secondary carnitine deficiency. We identified 13 isobutyryl-CoA dehydrogenase-deficient patients through newborn screening due to an elevation of C4-acylcarnitine in dried blood spots. Because C4-acylcarnitine represents both isobutyryl- and butyrylcarnitine, elevations are not specific for isobutyryl-CoA dehydrogenase deficiency but are also observed in short-chain acyl-CoA dehydrogenase deficiency.

Variations in IBD (ACAD8) in children with elevated C4-carnitine detected by tandem mass spectrometry newborn screening.

The isobutyryl-CoA dehydrogenase (IBD) enzyme is involved in the degradation of valine. IBD deficiency was first reported in 1998 and subsequent genetic investigations identified acyl-CoA dehydrogenase (ACAD) 8, now IBD, as the gene responsible for IBD deficiency. Only three individuals homozygous or compound heterozygous for variations in the IBD gene have been reported.

Marshall-Smith syndrome: natural history and evidence of an osteochondrodysplasia with connective tissue abnormalities.

The Marshall-Smith syndrome (MSS) is a distinct malformation syndrome characterized by accelerated skeletal maturation, relative failure to thrive, respiratory difficulties, mental retardation, and unusual facies, including prominent forehead, shallow orbits, blue sclerae, depressed nasal bridge, and micrognathia. At least 33 cases have been reported in the literature, mostly as single case reports or small series. The purpose of the present study is to report on the clinical findings and natural history of MSS in five children and to review the features of three others previously reported, with particular attention to the skeletal and connective tissue findings.