Expanding the reproductive organ phenotype of CHD7-spectrum disorder

CHD7 disorder is a multiple congenital anomaly syndrome with a highly variable phenotypic spectrum, and includes CHARGE syndrome. Internal and external genital phenotypes frequently seen in CHD7 disorder include cryptorchidism and micropenis in males, and vaginal hypoplasia in females, both thought to be secondary to hypogonadotropic hypogonadism. Here, we report 14 deeply phenotyped individuals with known CHD7 variants (9 pathogenic/likely pathogenic and 5 VOUS) and a range of reproductive and endocrine phenotypes. Reproductive organ anomalies were observed in 8 of 14 individuals and were more commonly noted in males (7/7), most of whom presented with micropenis and/or cryptorchidism. Kallmann syndrome was commonly observed among adolescents and adults with CHD7 variants. Remarkably, one 46,XY individual presented with ambiguous genitalia, cryptorchidism with Müllerian structures including uterus, vagina and fallopian tubes, and one 46,XX female patient presented with absent vagina, uterus and ovaries. These cases expand the genital and reproductive phenotype of CHD7 disorder to include two individuals with genital/gonadal atypia (ambiguous genitalia), and one with Müllerian aplasia.

Clinical Indications for Growth Hormone Therapy

Growth hormone (GH) is an injectable medication originally used to replace the deficiency of the hormone, but has expanded to treating conditions that may reduce growth and adult height even when the body maintains endogenous GH production. In the United States, there are 8 Food and Drug Administration (FDA)-approved indications for pediatric GH therapy: GH deficiency, Prader-Willi Syndrome, small for gestational age (SGA) without catch-up growth, idiopathic short stature, Turner syndrome, SHOX gene haploinsufficiency, Noonan Syndrome, and chronic renal insufficiency. We characterize the growth patterns and effects of GH treatment in each of these indications. We also review patterns of growth that warrant referral to a pediatric endocrinologist, as well as safety updates. This review is intended to guide practitioners on the initial evaluation and management of patients with short stature, and the indications for GH therapy.

The Role of GLP-1 Signaling in Hypoglycemia due to Hyperinsulinism

Incretin hormones play an important role in the regulation of glucose homeostasis through their actions on the beta cells and other tissues. Glucagon-like peptide-1 (GLP-1) and glucose dependent insulinotropic polypeptide (GIP) are the two main incretins and are secreted by enteroendocrine L- and K-cells, respectively. New evidence suggests that incretin hormones, particularly GLP-1, play a role in the pathophysiology of hyperinsulinemic hypoglycemia. In individuals with acquired hyperinsulinemic hypoglycemia after gastrointestinal surgery, including Nissen fundoplication and gastric bypass surgery, the incretin response to a meal is markedly increased and antagonism of the GLP-1 receptor prevents the hyperinsulinemic response. In individuals with congenital hyperinsulinism due to inactivating mutations in the genes encoding the beta cell K_ATP channels, the GLP-1 receptor antagonist, exendin-(9-39), increases fasting plasma glucose and prevents protein-induced hypoglycemia. Studies in human and mouse islets lacking functional K_ATP channels have demonstrated that the effect on plasma glucose is at least in part mediated by inhibition of insulin secretion resulting from lower cytoplasmic cAMP levels. The understanding of the role of incretin hormones in the pathophysiology of hyperinsulinemic hypoglycemia is important for the exploration of the GLP-1 receptor as a therapeutic target for these conditions. In this article, we will review incretin physiology and evidence supporting a role of the incretin hormones in the pathophysiology of hyperinsulinemic hypoglycemia, as well as results from proof-of concept studies exploring a therapeutic approach targeting the GLP-1 receptor to treat hyperinsulinemic hypoglycemia.

SAT-290 Expanded Phenotype Associated with RNF135 Intragenic Deletion in a Girl with Peripheral Precocious Puberty

Introduction: RNF135 gene is located within the 17q11.2 region and is often deleted in the NF1 contiguous microdeletion syndrome. Six individuals with suspected pathogenic mutations of RNF135 have been described with similar phenotypes including facial dysmorphism (downslanted palpebral fissures, elongated philtrum, broad nasal tip, thin upper lip, broad forehead), macrocephaly, tall stature, overgrowth, and learning disabilities. We present the first reported case of a patient with RNF135 intragenic deletion and precocious puberty. Clinical Case: Patient had ambiguous genitalia at birth, suspicious for CAH. Laboratory evaluation was normal. At age 2, she presented with breast and pubic hair development over the previous year. Leuprolide stimulation test was not consistent with central precocious puberty. Pelvic ultrasound revealed a paraovarian cyst that was drained at age 4 and pubertal development stabilized. At age 6, had progression of puberty with Tanner III breasts. MRI pelvis showed a large cyst of the left ovary and a post pubertal appearing uterus. Patient underwent left oophorectomy for numerous ovarian cysts and concern for progression of precocious puberty. Pathology showed a serous cystadenoma and pubertal ovary. At age 7 years 5 months, she had torsion of the right ovary and underwent laproscopic detorsion. Biopsy showed extensively hemorrhagic tissue with foci of ovarian stroma. Pubertal development was stable until age 7 years 10 months, when she presented with Tanner IV breasts and Tanner II pubic hair. MRI pelvis showed a multicystic right ovary with follicles. Since age 2, patient had tall stature, with height Z score ranging 3.45-4.47. She was diagnosed with focal epilepsy at age 3.5 years and had a PDA that was coiled at age 4. At age 7, chromosomal microarray showed an 88 base pair deletion at chromosome 17q11.2, including part of the RNF135 gene. Patient has dysmorphic facial features, including hypertelorism, upslanted palpebral fissures, bilateral epicanthal folds, flat nasal bridge, malar hypoplasia, high arched palate. Other dysmorphic body features include dolichocephaly and sandal gap between toes 1 and 2. Patient has fine motor, gross motor, and speech delays. Conclusion: Mutations in the RNF135 gene are rare, with phenotypes only described in 6 individuals to date. Our patient exhibits many phenotypic features seen in described patients with pathogenic variants in this gene, including dysmorphic facial features, developmental delay, and tall stature. This is the first reported case of a patient with RNF135 intragenic deletion presenting with peripheral precocious puberty, cystic ovaries, and focal epilepsy. This case describes several new clinical features that are thought to be associated with a rare RNF135-related overgrowth syndrome.

Comparisons of Schansitherium tafeli with Samotherium boissieri (Giraffidae, Mammalia) from the Late Miocene of Gansu Province, China

We are describing and figuring for the first time skulls of Schansitherium tafeli, which are abundant in the Gansu area of China from the Late Miocene. They were animals about the size of Samotherium with shorter necks that had two pairs of ossicones that merge at the base, which is unlike Samotherium. The anterior ossicones consist of anterior lineations, which may represent growth lines. They were likely mixed feeders similar to Samotherium. Schansitherium is tentatively placed in a very close position to Samotherium. Samotherium and Schansitherium represent a pair of morphologically very similar species that likely coexisted similarly to pairs of modern species, where the main difference is in the ossicones. Pairs of ruminants in Africa, for example, exist today that differ mostly in their horn shape but otherwise are similar in size, shape, and diet. The absence of Schansitherium from Europe is interesting, however, as Samotherium is found in both locations. While is it challenging to interpret neck length and ossicone shape in terms of function in combat, we offer our hypothesis as to how the two species differed in their fighting techniques.

The evolution and anatomy of the horse manus with an emphasis on digit reduction

We revisit digit reduction in the horse and propose that all five digits are partially present in the modern adult forelimb. Osteological descriptions of selected tetradactyl, tridactyl and monodactyl equids demonstrate the evolution of the forelimb. Histological, osteological and palaeontological evidence suggest that the Equus distal forelimb is more complex than traditionally conceived. The current understanding is that the horse distal forelimb consists of one complete digit (III) and two reduced splint metacarpals (II and IV). Metacarpals II and IV each exhibit a ventral ridge, which we suggest represents the undifferentiated digits I and V. These ridges are present in the tridactyl Mesohippus, but are absent in the tetradactyl Hyracotherium. The carpal articulations of the five metacarpals match those of pentadactyl taxa. Distally, the frog, a V-shaped structure on the ventral hoof represents digits II and IV, and the wings and hoof cartilages of the distal phalanx are digits I and V. We relate this revised interpretation of the Equus forelimb to Laetoli footprints, and suggest the Hipparion side impressions are created from the hooves of I and V, rather than from II and IV. We show shades of pentadactyly within the Equus manus.

Astragalar Morphology of Selected Giraffidae

The artiodactyl astragalus has been modified to exhibit two trochleae, creating a double pullied structure allowing for significant dorso-plantar motion, and limited mediolateral motion. The astragalus structure is partly influenced by environmental substrates, and correspondingly, morphometric studies can yield paleohabitat information. The present study establishes terminology and describes detailed morphological features on giraffid astragali. Each giraffid astragalus exhibits a unique combination of anatomical characteristics. The giraffid astragalar morphologies reinforce previously established phylogenetic relationships. We find that the enlargement of the navicular head is a feature shared by all giraffids, and that the primitive giraffids possess exceptionally tall astragalar heads in relation to the total astragalar height. The sivatheres and the okapi share a reduced notch on the lateral edge of the astragalus. We find that Samotherium is more primitive in astragalar morphologies than Palaeotragus, which is reinforced by tooth characteristics and ossicone position. Diagnostic anatomical characters on the astragalus allow for giraffid species identifications and a better understanding of Giraffidae.

The cervical anatomy of Samotherium, an intermediate-necked giraffid

Giraffidae are represented by many extinct species. The only two extant taxa possess diametrically contrasting cervical morphology, as the okapi is short-necked and the giraffe is exceptionally long-necked. Samotherium major, known from the Late Miocene of Samos in Greece and other Eurasian localities, is a key extinct giraffid; it possesses cervical vertebrae that are intermediate in the evolutionary elongation of the neck. We describe detailed anatomical features of the cervicals of S. major, and compare these characteristics with the vertebrae of the two extant giraffid taxa. Based on qualitative morphological characters and a quantitative analysis of cervical dimensions, we find that the S. major neck is intermediate between that of the okapi and the giraffe. Specifically, the more cranial (C2-C3) vertebrae of S. major represent a mosaic of features shared either with the giraffe or with the okapi. The more caudal (C5-C7) S. major vertebrae, however, appear transitional between the two extant taxa, and hence are more unique. Notably, the C6 of S. major exhibits a partially excavated ventral lamina that is strong cranially but completely absent on the caudal half of the ventral vertebral body, features between those seen in the giraffe and the okapi. Comprehensive anatomical descriptions and measurements of the almost-complete cervical column reveal that S. major is a truly intermediate-necked giraffid. Reconstructions of the neck display our findings.

Fossil evidence and stages of elongation of the Giraffa camelopardalis neck

Several evolutionary theories have been proposed to explain the adaptation of the long giraffe neck; however, few studies examine the fossil cervical vertebrae. We incorporate extinct giraffids, and the okapi and giraffe cervical vertebral specimens in a comprehensive analysis of the anatomy and elongation of the neck. We establish and evaluate 20 character states that relate to general, cranial and caudal vertebral lengthening, and calculate a length-to-width ratio to measure the relative slenderness of the vertebrae. Our sample includes cervical vertebrae (n=71) of 11 taxa representing all seven subfamilies. We also perform a computational comparison of the C3 of Samotherium and Giraffa camelopardalis, which demonstrates that cervical elongation occurs disproportionately along the cranial-caudal vertebral axis. Using the morphological characters and calculated ratios, we propose stages in cervical lengthening, which are supported by the mathematical transformations using fossil and extant specimens. We find that cervical elongation is anisometric and unexpectedly precedes Giraffidae. Within the family, cranial vertebral elongation is the first lengthening stage observed followed by caudal vertebral elongation, which accounts for the extremely long neck of the giraffe.