Autosomal-dominant brachydactyly type E is a congenital abnormality characterized by small hands and feet, which is a consequence of shortened metacarpals and metatarsals. We recently encountered a young gentleman exhibiting shortening of 4th and 5th fingers and toes. Initially, we suspected him having pseudopseudohypoparathyroidism (PPHP) because of normal biochemical parameters, including electrolyte, Ca, P, and parathyroid hormone (PTH) levels; however, his mother and maternal grandmother had the same conditions in their hands and feet. Furthermore, his mother showed normal biochemical parameters. To the best of our knowledge, PPHP is inherited via a mutated paternal allele, owing to the paternal imprinting of GNAS (guanine nucleotide binding protein, alpha stimulating) in the renal proximal tubule. Therefore, we decided to further analyze the genetic background in this family.
Whole exome sequencing was performed using genomic DNA from the affected mother, son, and the unaffected father as a negative control.
We selected the intersection between 45,490 variants from the mother and 45,646 variants from the son and excluded 27,512 overlapping variants identified from the father. By excluding homogenous and compound heterozygous variants and removing all previously reported variants, 147 variants were identified to be shared by the mother and son. Variants that had least proximities among species were excluded and finally 23 variants remained.
Among them, we identified a defect in parathyroid hormone like hormone (
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Ectopic adrenocorticotropic hormone (ACTH) syndrome is caused most frequently by a bronchial carcinoid tumor or by small cell lung cancer. Medullary thyroid carcinoma (MTC) is a rare etiology of ectopic ACTH syndrome. We describe a case of Cushing syndrome due to ectopic ACTH production from MTC in a 48-year-old male. He was diagnosed with MTC 14 years ago and underwent total thyroidectomy, cervical lymph node dissection and a series of metastasectomies. MTC was confirmed by the pathological examination of the thyroid and metastatic mediastinal lymph node tissues. Two years after his last surgery, he developed Cushingoid features, such as moon face and central obesity, accompanied by uncontrolled hypertension and new-onset diabetes. The laboratory results were compatible with ectopic ACTH syndrome. A bilateral adrenalectomy improved the clinical and laboratory findings that were associated with Cushing syndrome. This is the first confirmed case of ectopic ACTH syndrome caused by MTC in Korea.
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