Javier Aisenberg

Clinical, genetic, and structural basis of congenital adrenal hyperplasia due to 11β-hydroxylase deficiency

Significance Congenital adrenal hyperplasia resulting from mutations in the CYP11B1 gene, which encodes a steroidogenic enzyme 11β-hydroxylase, is a rare inherited disorder associated with hyperandrogenemia, short stature, hypertension, and virilization of female newborns. We present a comprehensive clinical, genetic, and hormonal characterization for 68 of 108 patients with a genotype from an International Consortium on Rare Steroid Disorders. We also use computational modeling to define the effect of each of the missense mutations on the structure of 11β-hydroxylase, information that can be used to predict clinical severity prenatally in high-risk mothers. Congenital adrenal hyperplasia (CAH), resulting from mutations in CYP11B1, a gene encoding 11β-hydroxylase, represents a rare autosomal recessive Mendelian disorder of aberrant sex steroid production. Unlike CAH caused by 21-hydroxylase deficiency, the disease is far more common in the Middle East and North Africa, where consanguinity is common often resulting in identical mutations. Clinically, affected female newborns are profoundly virilized (Prader score of 4/5), and both genders display significantly advanced bone ages and are oftentimes hypertensive. We find that 11-deoxycortisol, not frequently measured, is the most robust biochemical marker for diagnosing 11β-hydroxylase deficiency. Finally, computational modeling of 25 missense mutations of CYP11B1 revealed that specific modifications in the heme-binding (R374W and R448C) or substrate-binding (W116C) site of 11β-hydroxylase, or alterations in its stability (L299P and G267S), may predict severe disease. Thus, we report clinical, genetic, hormonal, and structural effects of CYP11B1 gene mutations in the largest international cohort of 108 patients with steroid 11β-hydroxylase deficiency CAH.

Fructosamine levels demonstrate improved glycemic control for some children attending a diabetes summer camp

Abstract: Residential summer camps for youths with diabetes may have a positive effect on glycemic control. Hemoglobin A1c (HbA1c) is considered the best measure of control, but it reflects too long a period to evaluate a camp session. The fructosamine test reflects control over a period of 2–3 wk and may be ideal for this purpose. A portable device was used to examine the relationship between 2 wk of glycemic control and the change in fructosamine in order to determine whether control improved at camp.

The Growth Hormone Receptor (GHR) c.899dupC Mutation Functions as a Dominant Negative: Insights into the Pathophysiology of Intracellular GHR Defects

CONTEXT GH insensitivity (GHI) is a condition characterized by pronounced IGF-I deficiency and severe short stature. We previously identified a novel compound heterozygous GH receptor (GHR) mutation, GHR:p.R229H/c.899dupC, in a patient presenting with GHI. The heterozygous p.R229H (prepeptide) variant was previously associated with GHI despite a lack of adequate functional studies. The novel heterozygous GHR:c.899dupC variant affects the critical JAK2-binding Box 1 region of the GHR intracellular domain; the duplication predicted a frameshift and early protein termination. OBJECTIVE The individual and synergistic effect(s) of the p.R229H and c.899dupC mutations on GHR function(s) were evaluated in reconstitution studies. RESULTS The recombinant human GHR (hGHR):p.R229H variant was readily expressed, and unexpectedly, GH-induced signal transducer and activator of transcription 5b (STAT5b) phosphorylation was comparable to that induced by wild-type hGHR. The truncated, immunodetected hGHR:c.899dupC variant, in contrast, was unresponsive to GH. To mimic a compound heterozygous state, the two variants were coexpressed, and strikingly, the presence of the hGHR:c.899dupC effectively abolished the GH-induced STAT5b activities that were observed with hGHR:p.R229H alone. Furthermore, hGHR:c.899dupC dose-dependently reduced the GH-induced STAT5b activities associated with hGHR:p.R229H. This dominant negative effect was also observed when hGHR:c.899dupC was coexpressed with wild-type hGHR. CONCLUSION The p.R229H variant, contrary to an earlier report, appeared to function like wild-type GHR and, therefore, is unlikely to cause GHI. The c.899dupC variant is a novel dominant negative mutation that disrupted normal GHR signaling and is the cause for the GHI phenotype of the reported patient.

Turner syndrome phenotype with 47,XXX karyotype: Further investigation warranted?

Approximately 1 of every 1000 newborn girls has a 47,XXX karyotype [Jones, 1997]. Clinical features shared by these girls may include tall stature, learning disabilities, and psychosocial issues [Jones, 1997]. This is quite different fromTurner syndrome,which occurs in approximately 1 in 3000 newborn girls and has a phenotype of neck webbing, short stature, and gonadal dysgenesis [Sybert, 2001]. We had the opportunity to care for two children who presented with short stature and clinical features of Turner syndrome and who had non-mosaic 47,XXX karyotypes on blood chromosome analysis with 45,X/46,XX/47,XXX mosaicism in buccal mucosa with FISH analysis or fibroblasts. We therefore suggest that individuals who have the clinical features of Turner syndrome with a 47,XXX lymphocyte karyotype deserve further evaluation with buccal mucosa FISH analysis or fibroblast studies. Patient 1 was the 2,806 g product of a full-term uncomplicated pregnancy. At age 7 years 6 months, height was 113 cm (3rd centile). Physical examination was notable for broad hands and broad neck, which in combination with her short stature, suggested the diagnosis of Turner syndrome. Chromosome analysis from 50 peripheral blood cells revealed a 47,XXX karyotype. Due to the discrepancy between clinical presentationandkaryotype, a swabof buccal epithelial cells was obtained for FISH analysis with bicolor X (DXZ1 Xred signal) and Y (DYZ3 Y-green signal) DNA specific probes and yielded a result of 47,XXX [69]/45,X[26]/ 46,XX[9] mosaicism. Patient 2 was the 2,778 g product of a full-term pregnancy. A heart murmur noted in the neonatal period resolved spontaneously. At 4 years of age, height was 95 cm (3rd centile). Physical examination was notable for a triangular shaped face, awidenasal bridge, and short fifth finger bilaterally. Initial chromosome studies from a peripheral blood sample revealed a 47,XXX karyotype in 50 cells. Subsequent cytogenetic analysis from a skin biopsy demonstrated a 47,XXX [3]/ 45,X[56] /46,XX[49] mosaic karyotype. It is estimated that 15% of individuals who have Turner syndrome have a mosaic karyotype involving one or two additional cell lines such as 46,XX, 46,XY, or 47,XXX [Sybert, 2002]. Overall, variability of the phenotype has been correlated with the proportion of the various cell lines [Partsch et al., 1994]. These differences included absence of edema at birth, increased likelihood for spontaneous menarche, increased likelihood for successful pregnancy conception, and increased incidence of developmental delay among women [Sybert, 2002]. The triple X phenotype, in the nonmosaic state, is associated with increased stature, normal fertility, decreased intellectual ability, and a possible increase in psychiatric problems [Jones, 1997]; however, when combinedwith amonosomyX cell line as in our patients, this phenotype is not observed [Sybert, 2002]. Because the diagnosis of XXX often is made after studying a single tissue sample from a patient, mosaicism of 45,X may be undetected. Recent advances in FISH technology allow for the determination of chromosome complement in cells obtainednon-invasively frombuccalmucosa. Thismakes a good clinical adjunct for these patientswhose phenotype does not match the karyotype determined by blood lymphocyte analysis [Abulhasan et al., 1999]. This also has bearing on clinical evaluation as individuals with a 45,X cell line should have cardiology evaluations to rule out coarctation of the aorta. Additional recommendations include audiology evaluation, thyroid screening, and diabetes surveillancewhich are issuesnot germaine to the XXX diagnosis [Sybert, 2001]. Our patients present further support for carrying out a cytogenetic evaluation of a second tissue when an individual’s clinical diagnosis is not supported by blood cell chromosome analysis. [Azcona et al., 1999; Sybert, 2001]. FISH analysis of buccal mucosa is a non-invasive *Correspondence to: Dr. Robert Wallerstein, M.D., Genetics Service, Joseph M. Sanzari Children’s Hospital, Hackensack University Medical Center, 30 Prospect Avenue, Hackensack, NJ, 07601. E-mail: rwallerstein@humed.com

Novel Dominant-Negative GH Receptor Mutations Expands the Spectrum of GHI and IGF-I Deficiency

Context: Autosomal-recessive mutations in the growth hormone receptor (GHR) are the most common causes for primary growth hormone insensitivity (GHI) syndrome with classical GHI phenotypically characterized by severe short stature and marked insulin-like growth factor (IGF)-I deficiency. We report three families with dominant-negative heterozygous mutations in the intracellular domain of the GHR causing a nonclassical GHI phenotype. Objective: To determine if the identified GHR heterozygous variants exert potential dominant-negative effects and are the cause for the GHI phenotype in our patients. Results: All three mutations (c.964dupG, c.920_921insTCTCAAAGATTACA, and c.945+2T>C) are predicted to result in frameshift and early protein termination. In vitro functional analysis of variants c.964dupG and c.920_921insTCTCAAAGATTACA (c.920_921ins14) suggests that these variants are expressed as truncated proteins and, when coexpressed with wild-type GHR, mimicking the heterozygous state in our patients, exert dominant-negative effects. Additionally, we provide evidence that a combination therapy of recombinant human growth hormone (rhGH) and rhIGF-I improved linear growth to within normal range for one of our previously reported patients with a characterized, dominant-negative GHR (c.899dupC) mutation. Conclusion: Dominant-negative GHR mutations are causal of the mild GHI with substantial growth failure observed in our patients. Heterozygous defects in the intracellular domain of GHR should, therefore, be considered in cases of idiopathic short stature and IGF-I deficiency. Combination therapy of rhGH and rhIGF-I improved growth in one of our patients.

Efficacy and safety of triptorelin 6-month formulation in patients with central precocious puberty

Abstract Background: Triptorelin is an established treatment for central precocious puberty (CPP) as 1- and 3-month formulations. The current triptorelin 22.5 mg 6-month formulation is approved for prostate cancer therapy. This is the first study in patients with CPP. Methods: The efficacy and safety of the triptorelin 6-month formulation in CPP were investigated. The primary objective was to evaluate the efficacy in achieving luteinizing hormone (LH) suppression to pre-pubertal levels at month 6. This was an international, non-comparative phase III study over 48 weeks. Eighteen medical centers in the US, Chile and Mexico participated. Forty-four treatment naïve patients (39 girls and five boys) aged at treatment start 2–8 years for girls and 2–9 years for boys with an advancement of bone age over chronological age ≥1 year were to be included. Triptorelin was administered im twice at an interval of 24 weeks. LH, follicle stimulating hormone (FSH) (basal and stimulated), estradiol (girls), testosterone (boys), auxological parameters, clinical signs of puberty and safety were assessed. Results: Forty-one patients (93.2%) showed pre-pubertal LH levels (stimulated LH ≤5 IU/L) at month 6 and maintained LH suppression through month 12. The percentage of patients with LH suppression exceeded 93% at each time point and reached 97.7% at month 12. No unexpected drug-related adverse events were reported. Conclusions: The triptorelin 6-month formulation was safe and effective in suppressing the pituitary-gonadal axis in children with CPP. The extended injection interval may improve compliance and increase comfort in the management of CPP.

Management of pediatric patients with type 1 diabetes.

One of the many consequences of the worldwide increase in obesity rates is increased rates of diabetes in both adults and children.1 In 2010, approximately 215,000 people younger than age 20 years in the United States had type 1 diabetes mellitus (T1D) or type 2 diabetes.2 In children and adolescents, T1D is the most frequently diagnosed type of diabetes.3 In the United States, the incidence of T1D in children younger than age 10 years was estimated to be 19.7 per 100,000 each year from 2002 to 2005,2 and this rate increases with age. Within the age group of 0 to 14 years, the highest incidence is found among children age 10 to 14 years, followed by those age 5 to 9 years, and then those age 0 to 4 years.4

Coincidence of multiple endocrine neoplasia type IIa and type 1 diabetes mellitus

Multiple endocrine neoplasia type IIa (MEN2a) is a well-described genetic condition characterized by medullary thyroid carcinoma, pheochromocytoma, and parathyroid adenomas. It is inherited in a dominant pattern with mutations of the RET oncogene known to be the causative factor. With the availability of genetic testing, management has changed from symptomatic treatment to DNA analysis for prophylactic intervention with the anticipation of medical issues becoming the standard of care. We present a 15 year-old boy with MEN2a who also has type 1 diabetes mellitus (DM1) and wish to consider whether this is a coincidental or etiological association.