Anna Pawlikowska-Haddal

Exome Sequencing for the Diagnosis of 46,XY Disorders of Sex Development

CONTEXT Disorders of sex development (DSD) are clinical conditions where there is a discrepancy between the chromosomal sex and the phenotypic (gonadal or genital) sex of an individual. Such conditions can be stressful for patients and their families and have historically been difficult to diagnose, especially at the genetic level. In particular, for cases of 46,XY gonadal dysgenesis, once variants in SRY and NR5A1 have been ruled out, there are few other single gene tests available. OBJECTIVE We used exome sequencing followed by analysis with a list of all known human DSD-associated genes to investigate the underlying genetic etiology of 46,XY DSD patients who had not previously received a genetic diagnosis. DESIGN Samples were either submitted to the research laboratory or submitted as clinical samples to the UCLA Clinical Genomic Center. Sequencing data were filtered using a list of genes known to be involved in DSD. RESULTS We were able to identify a likely genetic diagnosis in more than a third of cases, including 22.5% with a pathogenic finding, an additional 12.5% with likely pathogenic findings, and 15% with variants of unknown clinical significance. CONCLUSIONS Early identification of the genetic cause of a DSD will in many cases streamline and direct the clinical management of the patient, with more focused endocrine and imaging studies and better-informed surgical decisions. Exome sequencing proved an efficient method toward such a goal in 46,XY DSD patients.

Functional neuroimaging provides evidence of anomalous cerebral laterality in adults with Klinefelter's syndrome

This study aimed to characterize cerebral perfusion in men with Klinefelters syndrome, known to present specific deficits in language, using 99mTc‐ hexamethylpropylene‐amine‐oxime scintigraphy and Talairach normalization. While a perfusion asymmetry toward the left hemisphere was found in controls, perfusion was mostly symmetrical in Klinefelter patients in the upper temporal and lower parietal areas. Scores on verbal tests were inversely correlated with perfusion changes, providing neurobiological substrate of anomalous cerebral laterality.

Exome sequencing finds a novel PCSK1 mutation in a child with generalized malabsorptive diarrhea and diabetes insipidus.

Objectives: Congenital diarrhea disorders are a group of genetically diverse and typically autosomal recessive disorders that have yet to be well characterized phenotypically or molecularly. Diagnostic assessments are generally limited to nutritional challenges and histologic evaluation, and many subjects eventually require a prolonged course of intravenous nutrition. Here we describe next-generation sequencing techniques to investigate a child with perplexing congenital malabsorptive diarrhea and other presumably unrelated clinical problems; this method provides an alternative approach to molecular diagnosis. Methods: We screened the diploid genome of an affected individual, using exome sequencing, for uncommon variants that have observed protein-coding consequences. We assessed the functional activity of the mutant protein, as well as its lack of expression using immunohistochemistry. Results: Among several rare variants detected was a homozygous nonsense mutation in the catalytic domain of the proprotein convertase subtilisin/kexin type 1 gene. The mutation abolishes prohormone convertase 1/3 endoprotease activity as well as expression in the intestine. These primary genetic findings prompted a careful endocrine reevaluation of the child at 4.5 years of age, and multiple significant problems were subsequently identified consistent with the known phenotypic consequences of proprotein convertase subtilisin/kexin type 1 (PCSK1) gene mutations. Based on the molecular diagnosis, alternate medical and dietary management was implemented for diabetes insipidus, polyphagia, and micropenis. Conclusions: Whole-exome sequencing provides a powerful diagnostic tool to clinicians managing rare genetic disorders with multiple perplexing clinical manifestations.

How useful are serum IGF-I measurements for managing GH replacement therapy in adults and children?

The optimal dosing of growth hormone (GH) therapy is challenging due to high inter-individual variability in subcutaneous GH absorption and sensitivity to the drug. Optimal dosing would maximize patient gains in height, body composition, and metabolic outcomes while minimizing GH adverse events. The pulsatile secretion of GH, however, does not allow direct assessment of circulating GH levels as a measure of response to GH therapy. Insulin-like growth factor (IGF-I), a key marker of GH activity, has been shown to be useful in monitoring and adjusting GH dose during treatment of GH deficiency (GHD). Traditionally, monitoring IGF-I levels in response to GH therapy has been recommended for assessment of treatment compliance and safety. More recently, GH treatment guidelines have stated that IGF-I levels should also be used to guide GH dosing. This review examines whether individualized GH dosing based on the IGF-I response to GH therapy provides a better method for determining the GH replacement needs of pediatric and adult patients compared with conventional GH dosing, and whether IGF-I-based dosing improves outcomes such as height and body composition, with reduced side effects. Because IGF-I measurement presents its own difficulties, the current state of IGF-I assays is also discussed. The reviewed studies show that the use of GH dose adjustments based on IGF-I responses to GH therapy successfully reduces adverse events in adults with GHD and results in greater positive height attainment in children, without increasing adverse events. Long-term outcome studies are needed, as are internationally accepted guidelines for IGF-I measurement.

Growth hormone therapy with norditropin (somatropin ) in growth hormone deficiency

Introduction: Growth hormone (GH) is indicated for therapy of growth hormone deficiency (GHD) in pediatric and adult patients. Introduction of recombinant human GH (rhGH) improved access to GH therapy. Norditropin [somatropin (rDNA origin) injection] is rhGH, used for the replacement of endogenous GH in children and adults with GHD. Areas covered: The article reviews rhGH therapy in GHD indication with focus on Norditropin Nordiflex delivery system. The goals of therapy in children are to promote linear growth and restore normal body composition. In adults with GHD rhGH restores normal body composition, improves cardiac function and normalizes cardiovascular risk factors such as low-density lipoprotein cholesterol and C-reactive protein. Expert opinion: Adverse reactions of rhGH therapy include intracranial hypertension, fluid retention, glucose intolerance, and children may experience worsening of scoliosis and slipped capital femoral epiphysis. Increased risk for intracranial tumors has also been reported in teenagers and young adults treated with radiation to the head as children for a first neoplasm. RhGH therapy requires daily injections, therefore improved ease of use of delivery devices may improve treatment outcomes. Several rhGH devices have been developed, and the Norditropin FlexPro prefilled pen is the newest delivery system which has small dose increments, does not require reconstitution and has flexible storage features.

Hyperinsulinism presenting in childhood and treatment by conservative pancreatectomy.

OBJECTIVE To describe the uncommon presentation of hyperinsulinism in an 8-year-old boy. METHODS We describe the patients clinical findings, results from biochemical and imaging studies, surgical approach, and outcome. The discussion encompasses a review of literature that provided the basis for the diagnostic and surgical approach applied to this patients case. RESULTS An obese 8.5-year-old boy initially presented with hypoglycemic seizures after initiation of dietary changes to treat obesity. Biochemical analysis indicated hyperinsulinism. Endoscopic ultrasonography showed no pancreatic lesions suggestive of insulinoma. Genetic studies identified no known mutations in the ABCC8, KCNJ11, GCK, or GLUD1 genes. Selective arterial calcium stimulation and hepatic venous sampling did not document a focal source for hyperinsulinism in the pancreas, and positron emission tomography with 18-fluoro-L-3,4-dihydroxyphenylalanine showed diffusely increased uptake in the pancreas. The patient ultimately required partial pancreatectomy because of continued hypoglycemia while taking diazoxide and octreotide. Intraoperative glucose monitoring directed the extent of surgical resection. A 45% pancreatectomy was performed, which resolved the hypoglycemia but led to impaired glucose tolerance after surgery. CONCLUSION The unusual presentation of hyperinsulinism in childhood required a personalized approach to diagnosis and surgical management using intraoperative glucose monitoring that resulted in a conservative pancreatectomy.