Expanding DSD Phenotypes Associated with Variants in the DEAH-Box RNA Helicase DHX37

Missense variants in the RNA-helicase DHX37 are associated with either 46,XY gonadal dysgenesis or 46,XY testicular regression syndrome (TRS). DHX37 is required for ribosome biogenesis, and this subgroup of XY DSD is a new human ribosomopathy. In a cohort of 140 individuals with 46,XY DSD, we identified 7 children with either 46,XY complete gonadal dysgenesis or 46,XY TRS carrying rare or novel DHX37 variants. A novel p.R390H variant within the RecA1 domain was identified in a girl with complete gonadal dysgenesis. A paternally inherited p.R487H variant, previously associated with a recessive congenital developmental syndrome, was carried by a boy with a syndromic form of 46,XY DSD. His phenotype may be explained in part by a novel homozygous loss-of-function variant in the <i>NGLY1</i> gene, which causes a congenital disorder of deglycosylation. Remarkably, a homozygous p.T477H variant was identified in a boy with TRS. His fertile father had unilateral testicular regression with typical male genital development. This expands the DSD phenotypes associated with DHX37. Structural analysis of all variants predicted deleterious effects on helicase function. Similar to all other known ribosomopathies, the mechanism of pathogenesis is unknown.

SUN-027 Testicular Regression Syndrome, an Underdiagnosed Cause of Hypergonadotropic Hypogonadism

Background: Testicular regression syndrome (TRS), also known as vanishing testes syndrome, is a condition of 46, XY males presenting with male phenotypic genitalia and testicular absence. Normal testes are thought to have once existed in fetal life and subsequently atrophied following a catastrophic event. It may present as partial or complete absence of testicular tissue. Fibrotic remnants are commonly found upon surgical exploration. Case: This is the case of a 20-year-old male with a birth-diagnosis of primary hypogonadism. The patient was born prematurely at 5 months following a motor vehicle accident that resulted in his mother’s death. Neonatal evaluation for cryptorchidism revealed no radiological evidence of intra-abdominal testicular mass. Referral to a pediatric-endocrinologist was done at early childhood. Testosterone replacement was started at 12 years of age and pubarche was adequate. After surgical exploration, a testicular remnant was surgically removed. Pathology report revealed fibrotic tissue, yet no histological testicular tissue was found. Due to lack of testes in the scrotum, testicular prosthesis was implanted at age 14, but the etiology of the hypogonadism was never elucidated. The patient was initially seen in our adult-endocrinology clinics at age 21. Upon evaluation, secondary sex characteristics were adequate for age. Penile length was of 3.5 inches. Bilateral testicular prostheses were palpable, and no gynecomastia was present. Despite testosterone replacement, total testosterone was 3.38 ng/ml (n; 2.41-8.27 ng/ml), FSH was 106 mIU/ml (n; 1.4-18.1 mIU/ml) and LH was 34.7 mIU/ml ml (n; 1.5-9.3 miu/ml). Based on history, laboratory workup and surgical pathology, TRS was presumed as the etiology of this patient’s hypogonadism. Testosterone therapy was adjusted to reach physiological expected levels. Conclusion: TRS is an underdiagnosed cause of hypergonadotropic hypogonadism. It is supposed that the initial embryologic development was normal, followed by a vascular accident. There is no clear recommended approach for evaluating a patient once the diagnosis of TRS is suspected. Diagnostic methods may include hormonal and karyotype testing, imaging, and surgical exploration. Furthermore, although clinical recommendations have been published for other disorders of sex development, TRS management has been understudied. Testosterone replacement therapy at the typical time of puberty ensures the development of secondary sexual characteristics, bone health and pubertal growth. Unlike Klinefelter syndrome and cryptorchidism, TRS has not been associated with increased risk of cancer. Thus, it is important to establish the etiology to avoid invasive and unnecessary workup, which will result in psychological distress and excessive healthcare costs.

Severe Degenerative Changes in Cryptorchid Testes in Japanese Black Cattle

This is a histopathologic and endocrinologic study of 6 calves diagnosed with cryptorchidism. Cases 1–3 were diagnosed as resembling testicular regression syndrome. In cases 1 and 2, the extracted tissue was a small, firm, gray-white mass, and there was lack of obvious testicular tissue in case 3. Histopathologically, the excised tissue in cases 1–3 was a fibrotic testicular remnant with inflammation, mineralization, hemosiderin-laden macrophages or lipofuscin-laden macrophages, and lack of germ cells and interstitial endocrine cells. These findings were compared with cases 4–6, which were diagnosed as testicular hypoplasia due to cryptorchidism. These cases had small but otherwise grossly unremarkable intra-abdominal testicular tissue and histologically had a few germ cells and sustentacular cells with arrested spermatogenesis and an increase in interstitial endocrine cells. Cases 1–3 had more severe degenerative changes compared with cases 4–6. In case 2, the average diameter of the seminiferous tubules was much smaller than in cases 4–6, and there were few tubule cross sections. Anti-Müllerian hormone (214 pg/ml) was detected in the plasma of case 2. Based on the macroscopic and histopathologic findings as well as endocrinologic profiles, the testicular degeneration in cases 1–3 was considered similar to that of testicular regression syndrome. In this condition, it is thought that a normally developing intra-abdominal testis undergoes degeneration due to heat or a vascular disorder such as torsion.