A Case with NAD(P)HX Dehydratase (NAXD) Deficiency: A Newly Defined Mutation in a Novel Neurodegenerative Disorder.

Introduction: Nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) are required redox equivalents for essential biochemical reactions. Their hydrated forms, NADHX and NAD(P)HX, are inhibitors for several dehydrogenases and cause harmful byproducts. NAD(P)HX dehydratase (NAXD) and NAD(P)HX epimerase (NAXE) together form the nicotinamide repair system. Case Presentation: A 7-month-old boy was admitted due to myoclonic seizures, impaired consciousness, and rapid loss of head control. One of his siblings regressed after a febrile seizure and died at 7 months. He had lethargy and axial hypotonia but skin lesions and organomegaly were not noted. Basal metabolic tests were within normal limits except serum and cerebrospinal fluid lactate levels, which were mildly elevated. Mitochondrial cocktail was added to the antiepileptic treatment with suspicion of mitochondrial disease. Whole-exome sequencing showed a novel homozygous mutation (c.247G>A) in the NAXD gene. His seizures stopped within a few weeks. However, he died at the age of 18 months. Discussion: Prominent features of NAXD deficiency are progressive neurological deterioration after fever, cardiomyopathy, skin lesions, and premature death. Unlike the cases reported in the literature, our patient had neither preceding fever nor skin lesion during follow-up. It appears that cases show phenotypic diversity.

A Case of Congenital Central Hypothyroidism Caused by a Novel Variant (Gln1255Ter) in IGSF1 Gene

Loss-of-function mutations in the immunoglobulin superfamily, member 1 (IGSF1) gene cause X-linked central hypothyroidism, and therefore its mutation affects mainly males. Central hypothyroidism in males is the hallmark of the disorder, however some patients additionally present with hypoprolactinemia, transient and partial growth hormone deficiency, early/normal timing of testicular enlargement but delayed testosterone rise in puberty, and adult macro-orchidism. Here, we report a boy with congenital central hypothyroidism caused by a novel variant in the IGSF1 gene. In our patient, early testicular enlargement but delayed testosterone rise with central hypothyroidism and hypoprolactinemia were the most important clues for diagnosis. In genetic analysis, we identified a novel, hemizygous nonsense c.3763 C>T (G1n1255Ter) variant in IGSF1 gene. To our knowledge, this is the first reported case of IGSF1 deficiency from Turkey.

Benign recurrent intrahepatic cholestasis type 2 in a child: A case report and novel mutation.

Benign recurrent intrahepatic cholestasis is a rare disorder characterized by recurrent episodes of cholestatic jaundice without liver damage. A mutation in the ABCB11 gene encoding bile salt export pump protein causes the disease. A 16-year-old boy with severe jaundice is presented here. His laboratory tests were consistent with intrahepatic cholestasis despite having normal gamma-glutamyl transpeptidase levels. Acute and chronic liver diseases with viral, metabolic, and autoimmune etiology were excluded. Magnetic resonance imaging revealed normal intra- and extrahepatic bile ducts. A liver biopsy showed cholestasis in the centrilobular and intermediate zones and sinusoidal dilatation. Genetic testing revealed a homozygous c.3083_3084delCAinsTG (Ala1028Val) mutation in the ABCB11 gene. The patient was treated with ursodeoxycholic acid 20 mg/kg/day and cholestyramine 4 g twice daily, and total bilirubin decreased to normal ranges after two months of therapy. This mutation (c.3083_3084delCAinsTG) in the ABCB11 gene is the first reported in a patient with benign recurrent intrahepatic cholestasis type 2.