A novel autosomal recessive lipodystrophy syndrome due to homozygous LMNA variant.

BACKGROUND: Despite major advances in understanding the molecular basis of various genetic lipodystrophy syndromes, some rare patients still remain unexplained. CASES: We report a novel autosomal recessive lipodystrophy affecting two sisters aged 17 and 19 years and characterised by early onset intellectual disability, and subsequent development of near-generalised loss of subcutaneous fat with diabetes mellitus, extreme hypertriglyceridemia, hepatic steatosis, short stature, clinodactyly, joint contractures, leiomyoma of uterus and cataracts in childhood. The lipodystrophy was more pronounced in the upper and lower extremities, and there was no associated muscular hypertrophy. Using whole exome sequencing in this consanguineous Hispanic pedigree, we report disease-causing homozygous p.Arg545His LMNA variant in the affected subjects, and confirm the lack of pathogenic variants in other known lipodystrophy genes. The mother and a younger brother were both heterozygous for p.Arg545His LMNA variant and were overweight with acanthosis nigricans without any evidence of lipodystrophy. Our patients are distinct from previously reported autosomal recessive lipodystrophy syndromes and have no overlap with other autosomal recessive laminopathies, including mandibuloacral dysplasia, Emery-Dreifuss muscular dystrophy and Charcot-Marie-Tooth neuropathy. CONCLUSION: Our report of this unusual familial generalised lipodystrophy syndrome adds to the pleiotropy associated with biallelic autosomal recessive LMNA variants.

Transient central diabetes insipidus induced by ketamine infusion.

OBJECTIVE: Report a case of central diabetes insipidus (DI) associated with ketamine infusion. CASE SUMMARY: A 2-year-old girl with long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency and stable hypertrophic cardiomyopathy was admitted to the pediatric intensive care with pneumonia. She subsequently developed respiratory failure and required intubation. Continuous ketamine infusion was used for the sedation and facilitation of mechanical ventilation. Shortly after infusion of ketamine, the patient developed DI and responded appropriately to vasopressin. DISCUSSION: The Naranjo adverse drug reaction probability scale indicated a probable relationship between the development of central DI and ketamine. The most likely mechanism involves ketamine's antagonist action on N-methyl-d-aspartate receptors, resulting in inhibition of glutamate-stimulated arginine vasopressin release from the neurohypophysis. CONCLUSION: This is the second case report of ketamine-induced central DI and the only report in children. Clinicians who sedate children with continuous ketamine infusions should monitor patients for developing signs and symptoms of DI by measuring serum sodium and urine output prior to, during, and after ketamine infusion in order to make a timely diagnosis of this potentially serious complication.

Phenotypic and Genotypic Characterization and Treatment of a Cohort With Familial Tumoral Calcinosis/Hyperostosis-Hyperphosphatemia Syndrome.

Familial tumoral calcinosis (FTC)/hyperostosis-hyperphosphatemia syndrome (HHS) is a rare disorder caused by mutations in the genes encoding fibroblast growth factor-23 (FGF23), N-acetylgalactosaminyltransferase 3 (GALNT3), or KLOTHO. The result is functional deficiency of, or resistance to, intact FGF23 (iFGF23), causing hyperphosphatemia, increased renal tubular reabsorption of phosphorus (TRP), elevated or inappropriately normal 1,25-dihydroxyvitamin D3 (1,25D), ectopic calcifications, and/or diaphyseal hyperostosis. Eight subjects with FTC/HHS were studied and treated. Clinical manifestations varied, even within families, ranging from asymptomatic to large, disabling calcifications. All subjects had hyperphosphatemia, increased TRP, and elevated or inappropriately normal 1,25D. C-terminal FGF23 was markedly elevated whereas iFGF23 was comparatively low, consistent with increased FGF23 cleavage. Radiographs ranged from diaphyseal hyperostosis to massive calcification. Two subjects with severe calcifications also had overwhelming systemic inflammation and elevated C-reactive protein (CRP). GALNT3 mutations were identified in seven subjects; no causative mutation was found in the eighth. Biopsies from four subjects showed ectopic calcification and chronic inflammation, with areas of heterotopic ossification observed in one subject. Treatment with low phosphate diet, phosphate binders, and phosphaturia-inducing therapies was prescribed with variable response. One subject experienced complete resolution of a calcific mass after 13 months of medical treatment. In the two subjects with systemic inflammation, interleukin-1 (IL-1) antagonists significantly decreased CRP levels with resolution of calcinosis cutis and perilesional inflammation in one subject and improvement of overall well-being in both subjects. This cohort expands the phenotype and genotype of FTC/HHS and demonstrates the range of clinical manifestations despite similar biochemical profiles and genetic mutations. Overwhelming systemic inflammation has not been described previously in FTC/HHS; the response to IL-1 antagonists suggests that anti-inflammatory drugs may be useful adjuvants. In addition, this is the first description of heterotopic ossification reported in FTC/HHS, possibly mediated by the adjacent inflammation. © 2016 American Society for Bone and Mineral Research.