Using Human Induced Pluripotent Stem Cell-Derived Organoids to Identify New Pathologies in Patients With PDX1 Mutations.

BACKGROUND & AIMS: Two patients with homozygous mutations in PDX1 presented with pancreatic agenesis, chronic diarrhea, and poor weight gain, the causes of which were not identified through routine clinical testing. We aimed to perform a deep analysis of the stomach and intestine using organoids derived from induced pluripotent stem cells from PDX1188delC/188delC patients. METHODS: Gastric fundic, antral, and duodenal organoids were generated using induced pluripotent stem cell lines from a PDX1188delC/188delC patient and an isogenic induced pluripotent stem cell line where the PDX1 point mutation was corrected. RESULTS: Patient-derived PDX1188delC/188delC antral organoids exhibited an intestinal phenotype, whereas intestinal organoids underwent gastric metaplasia with significant reduction in enteroendocrine cells. This prompted a re-examination of gastric and intestinal biopsy specimens from both PDX1188delC/188delC patients, which recapitulated the organoid phenotypes. Moreover, antral biopsy specimens also showed increased parietal cells and lacked G cells, suggesting loss of antral identity. All organoid pathologies were reversed upon CRISPR-mediated correction of the mutation. CONCLUSIONS: These patients will now be monitored for the progression of metaplasia and gastrointestinal complications that might be related to the reduced gastric and intestinal endocrine cells. This study demonstrates the utility of organoids in diagnosing uncovered pathologies.

4-Hour postoperative PTH level predicts hypocalcemia after thyroidectomy in children.

BACKGROUND: Hypocalcemia occurs frequently after a total thyroidectomy in pediatric patients. Four hour postoperative PTH monitoring predicts the need for calcium supplementation in the adult thyroidectomy population. We evaluated the role of the 4 h postoperative PTH level in determining the need for calcium supplementation after thyroidectomy in the pediatric population. METHODS: This is a retrospective review of children undergoing total thyroidectomy by a single pediatric surgeon from July 2011 through July 2018. Intact PTH obtained four hours postoperatively determined the need for calcium supplementation for patients beginning in November 2014 onward. Serum total calcium levels were monitored concurrently with serum intact PTH levels. Serum calcium levels were followed in our Multispecialty Pediatric Endocrine Surgery clinic within the month following thyroidectomy. RESULTS: From July 2011 through July 2018, there were a total of 56 total thyroidectomies at our institution. Prior to November 2014, all pediatric total thyroidectomies received calcium supplementation per our institutional protocol. Based on ionized calcium levels, 26.3% (5/19) of children developed hypocalcemia. From November 2014 to July 2018, 37 pediatric patients required total thyroidectomies. 29.7% (11/37) had low 4-h postoperative PTH levels. 72.7% (8/11) patients with low 4-h postoperative PTH levels had corresponding postoperative day 1 total calcium levels less than 8.5 or ionized calcium levels less than 1.12, and five children (45.5%) developed symptomatic hypocalcemia. 70% (26/37) of children had normal 4-h postop PTH levels, with only 5 (19%) ever developing hypocalcemia. No patients with a normal postop PTH level developed symptomatic hypocalcemia or required IV calcium repletion. A single 4-h postoperative PTH <10 pg/dl for identifying hypocalcemia has a sensitivity of 81% and specificity of 91%, with AUC 0.81. CONCLUSION: The 4-h postoperative serum PTH level can help determine the need for calcium supplementation in pediatric patients undergoing total thyroidectomy, thereby reducing unnecessary calcium supplementation and serial lab draws to monitor for postoperative hypocalcemia. LEVEL OF EVIDENCE: Level II.

Advances in the Classification and Treatment of Osteogenesis Imperfecta.

Osteogenesis imperfecta (OI) is a rare disorder of type 1 collagen with 13 currently identified types attributable to inherited abnormalities in type 1 collagen amount, structure, or processing. The disease is characterized by an increased susceptibility to bony fracture. In addition to the skeletal phenotype, common additional extraskeletal manifestations include blue sclerae, dentinogenesis imperfecta, vascular fragility, and hearing loss. Medical management is focused on minimizing the morbidity of fractures, pain, and bone deformities by maximizing bone health. Along with optimizing Vitamin D status and calcium intake and physical/occupational therapy, individualized surgical treatment may be indicated. Pharmacological therapy with bisphosphonate medications is now routinely utilized for moderate to severe forms and appears to have a good safety profile and bone health benefits. New therapies with other anti-resorptives as well as anabolic agents and transforming growth factor (TGF)ß antibodies are in development. Other potential treatment modalities could include gene therapy or mesenchymal cell transplant. In the future, treatment choices will be further individualized in order to reduce disease morbidity and mortality.

Isodicentric Y mosaicism involving a 46, XX cell line: Implications for management.

Carriers of isodicentric Y (idicY) mosaicism exhibit a wide range of clinical features, including short stature, gonadal abnormalities, and external genital anomalies. However, the phenotypic spectrum for individuals carrying an idicY and a 46, XX cell line is less clearly defined. A more complete description of the phenotype related to idicY is thus essential to guide management related to pubertal development, fertility, and gonadoblastoma risk in mosaic carriers. Findings from the evaluation of twin females with an abnormal karyotype, 48, XX, +idic(Yq) x2/47, XX, +idic(Yq)/46, XX, are presented to highlight the importance of interdisciplinary care in the management of multifaceted disorders of sex development.

Bone mineral density in young adult survivors of acute lymphoblastic leukemia.

BACKGROUND: The purpose of the current study was to determine the prevalence of low bone mineral density (BMD) (ie, osteopenia) and identify factors associated with low BMD in young adult survivors of childhood acute lymphoblastic leukemia (ALL). METHODS: Dual energy x-ray absorptiometry was used to evaluate BMD in 74 randomly selected, long-term childhood ALL survivors initially treated in Minneapolis/St. Paul, Minnesota. Growth hormone (GH)-releasing hormone-arginine stimulation testing was conducted to evaluate peak GH level, and insulin-like growth factor I (IGF-I) and other markers of endocrine functioning were also evaluated in relation to BMD. RESULTS: The mean age at the time of interview was 30 years, and the mean time since diagnosis was 24 years. Low BMD (Z-score, < or = -1) was present in 24% of subjects, including 1 with osteoporosis. Low BMD was substantially more prevalent in men than in women and was strongly associated with short height. The mean height Z-score for those with low BMD was -1.44, compared with a height Z-score of -0.39 (P < .01) for those with normal BMD. GH insufficiency, low IGF-I Z-score, and current smoking were also suggestive risk factors for low BMD. CONCLUSIONS: In this long-term follow-up study of childhood ALL survivors, low BMD was found to be more prevalent than expected based on population normative data, specifically in men. The health consequences of early-onset BMD problems in childhood ALL survivors need to be carefully monitored.