Identification of the first promoter-specific gain-of-function SOX9 missense variant (p.E50K) in a patient with 46,XX ovotesticular disorder of sex development.

SOX9, a transcription factor, is expressed in the undifferentiated XX and XY gonads. SRY induces significant upregulation of SOX9 expression in XY gonads. Loss-of-function SOX9 variants cause testicular dysgenesis in 46,XY patients, while duplication of the total gene or the upstream regulatory region results in testicular development in 46,XX patients. However, gain-of-function (GoF) SOX9 variants have not been reported previously. We report the case of a 16-year-old female patient with a 46,XX karyotype who had masculinized external genitalia and unilateral ovotestis. Next-generation sequencing-based genetic screening for disorders of sex development led to the identification of a novel SOX9 variant (p.Glu50Lys), transmitted from the phenotypically normal father. Expression analysis showed that E50K-SOX9 enhanced transactivation of the luciferase reporter containing the testis enhancer sequence core element compared with that containing the wildtype-SOX9. This GoF activity was not observed in the luciferase reporter containing Amh, the gene for anti-Müllerian hormone. We genetically engineered female mice (Sox9E50K/E50K ), and they showed no abnormalities in the external genitalia or ovaries. In conclusion, a novel SOX9 variant with a promoter-specific GoF activity was identified in vitro; however, the disease phenotype was not recapitulated by the mouse model. At present, the association between the GoF SOX9 variant and the ovotestis phenotype remains unclear. Future studies are needed to verify the possible association.

Copy-number analysis of Y-linked loci in young men with non-obstructive azoospermia: Implications for the rarity of early onset mosaic loss of chromosome Y.

PURPOSE: Mosaic loss of chromosome Y (mLOY) is a common feature in elderly men. If mLOY can also occur in young men, it may lead to spermatogenic failure due to loss of spermatogenic genes. Indeed, previous studies detected the 45,X/46,XY karyotype in a few young men with spermatogenic failure. The present study aimed to clarify the frequency of cryptic mLOY in reproductive-aged men with spermatogenic failure. METHODS: We studied 198 men at ages 24-55 years who presented with etiology-unknown non-obstructive azoospermia. Prior this study, these patients underwent G-banding analysis for 20 leukocytes and were found to have 46,XY karyotype. We analyzed copy numbers of chromosome Y in blood cells by using semi-quantitative multiplex PCR for AMELY/AMELX, array-based comparative genomic hybridization (CGH) for the AMELY locus, and droplet digital PCR for SRY, USP9Y, and UTY. RESULTS: Multiplex PCR showed borderline low AMELY/AMELX ratios in three patients. However, for the three patients, CGH excluded deletion of the AMELY locus, and droplet digital PCR suggested preserved copy numbers of all tested loci. CONCLUSION: This study highlights the rarity of leukocyte mLOY in reproductive-aged men with spermatogenic failure. In addition, our data imply that standard karyotyping is sufficient to screen early onset mLOY.

KLF11 variant in a family clinically diagnosed with early childhood-onset type 1B diabetes.

KLF11 is the causative gene for maturity-onset diabetes of the young 7 (MODY7). KLF11 regulates insulin gene expression through binding to the GC box in the promoter. To date, only two KLF11 mutations have been identified in three families with early-onset type 2 diabetes. Here, we report a novel KLF11 variant associated with early childhood-onset type 1B diabetes. The proband and his younger sister exhibited hyperglycemia at age 1 year, and their mother developed diabetes at age 4 years. These three individuals required insulin injection from the initial phase of the disease. Being negative for islet cell autoantibodies, they were diagnosed with type 1B diabetes. Mutation screening for 30 diabetes-associated genes identified a heterozygous KLF11 variant (p.His418Gln) in the proband and his sister. The variant was also detected in the affected mother, as well as in the allegedly unaffected maternal grandmother. In silico analyses indicated that this variant involves a highly conserved histidine residue in the first C2 H2 zinc finger domain which ligates a zinc ion. In vitro analyses showed that expression levels and intracellular localization of His418Gln-KLF11 were comparable to those of wildtype (WT)-KLF11. Luciferase assays demonstrated that while WT-KLF11 suppressed the activity of a 6 × GC box-containing reporter, His418Gln-KLF11 lacked the suppressive effect. Notably, His418Gln-KLF11 canceled the suppressive effect of co-transfected WT-KLF11. Such a dominant-negative effect was absent in the previously reported Ala347Ser-KLF11 variant. These results indicate that specific variants of KLF11 (MODY7) with a dominant-negative effect underlie early childhood-onset type 1B diabetes with incomplete penetrance. This study documents a novel monogenic mutation associated with diabetes in children.

A severely short-statured girl with 47,XX, + 14/46,XX,upd(14)mat, mosaicism.

The predominant symptoms of trisomy 14 mosaicism are prenatal and postnatal growth failure, ear abnormalities, congenital heart disease, developmental delay, and genitourinary abnormalities. Maternal uniparental disomy of chromosome 14 (upd(14)mat) presents discernible clinical features such as prenatal and postnatal growth failure, hypotonia, precocious puberty, and obesity. Given the small number of previously reported patients with a combination of trisomy 14 mosaicism and upd(14)mat, the detailed clinical features of these patients remain to be elucidated. Here we report a severely short-statured girl with feeding difficulties and failure to thrive, ear abnormalities, deafness, small hands, and developmental delay. Karyotyping, FISH analysis, methylation analysis, and microsatellite marker analysis using her leukocytes and buccal cells showed that she had a combination of trisomy 14 mosaicism and upd(14)mat. Furthermore, a comparison of the clinical features of this patient with those of previously reported patients with genetic anomalies including the combination of trisomy 14 mosaicism and upd(14)mat or upd(14)mat suggested that the severe short stature observed in patients with a combination of trisomy 14 mosaicism and upd(14)mat stemmed from the synergic effect of these two events. In severely short-statured patients with trisomy 14 mosaicism, we should be aware of the possible coexistence of upd(14)mat.

Comprehensive screening for monogenic diabetes in 89 Japanese children with insulin-requiring antibody-negative type 1 diabetes.

BACKGROUND: Mutations in causative genes for neonatal diabetes or maturity-onset diabetes of the young have been identified in multiple patients with autoantibody-negative type 1 diabetes (T1D). OBJECTIVES: We aimed to clarify the prevalence and phenotypic characteristics of monogenic abnormalities among 89 children with autoantibody-negative insulin-requiring T1D. METHODS: Mutations in 30 genes were screened using next-generation sequencing, and copy-number alterations of 4 major causative genes were examined using multiplex-ligation-dependent probe amplification. We compared the clinical characteristics between mutation carriers and non-carriers. RESULTS: We identified 11 probable pathogenic substitutions (6 in INS , 2 in HNF1A , 2 in HNF4A , and 1 in HNF1B ) in 11 cases, but no copy-number abnormalities. Only 2 mutation carriers had affected parents. De novo occurrence was confirmed for 3 mutations. The non-carrier group, but not the carrier group, was enriched with susceptible HLA alleles. Mutation carriers exhibited comparable phenotypes to those of non-carriers, except for a relatively normal body mass index (BMI) at diagnosis. CONCLUSIONS: This study demonstrated significant genetic overlap between autoantibody-negative T1D and monogenic diabetes. Mutations in INS and HNF genes, but not those in GCK and other monogenic diabetes genes, likely play critical roles in children with insulin-requiring T1D. This study also suggests the relatively high de novo rates of INS and HNF mutations, and the etiological link between autoimmune abnormalities and T1D in the non-carrier group. Carriers of monogenic mutations show non-specific phenotypes among all T1D cases, although they are more likely to have a normal BMI at diagnosis than non-carriers.

Severe Hypernatremia in Combined Diabetic Ketoacidosis and Hyperglycemic Hyperosmolar State: A Case Report of Two Japanese Children.

As sodium level in diabetic ketoacidosis (DKA) and hyperglycemic hyperosmolar state (HHS) is usually low, normal, or slightly elevated, severe hypernatremia with DKA and/or HHS is rare. Case 1 was a 14-year-old boy, presenting with typical laboratory test values and symptoms consistent with DKA and HHS. His corrected sodium level, 172 mEq/L, might have occurred as a result of consuming 6 L/day of highly carbonated, carbohydrate- and sodium-rich drinks during the week preceding the diagnosis. This patient developed right lung artery thrombosis, which did not require treatment. Case 2 was a 10-year-old girl, presenting with typical laboratory test values and symptoms of DKA and HHS. Her corrected sodium level, 175 mEq/L, might have occurred as a result of large electrolyte-free water loss associated with osmotic diuresis. These two cases of patients presenting with DKA-HHS and severe hypernatremia are the first to be reported in Japan.

The first Japanese case of central precocious puberty with a novel MKRN3 mutation.

MKRN3, located on chromosome 15q11.2, encodes makorin ring-finger 3, which is an upstream suppressor of the hypothalamic-pituitary-gonadal axis. Mutation of this gene induces central precocious puberty (CPP). As MKRN3 is maternally imprinted, only the paternal allele is expressed. This is the first report of an 8-year-old Japanese girl with CPP caused by a novel frameshift mutation in MKRN3 (p.Glu229Argfs*3).

Developmental delay and failure to thrive in a 7-month-old baby boy with spontaneous transient Graves' thyrotoxicosis: a case report.

BACKGROUND: Thyroid dysfunction can induce developmental delay and failure to thrive in infancy. Congenital hypothyroidism is one of the common causes of these symptoms in infancy. By contrast, hyperthyroidism is a rare cause of these symptoms in infancy. CASE PRESENTATION: A 7-month-old Japanese baby boy was examined for developmental delay and failure to thrive. Blood tests were performed, which showed low levels of thyroid-stimulating hormone (<0.01 µU/mL) and high levels of free thyroxine (2.14 pg/mL). He was referred to our hospital at 8 months of age. His height was 64 cm (-2.7 standard deviation) and his weight was 6085 g (-2.5 standard deviation). No goiter was detected on examination. His thyrotropin receptor antibody was slightly high (3.9 IU/L), whereas thyroid stimulating antibody, anti-thyroglobulin antibody, and thyroid peroxidase antibody were within normal range. These blood findings indicated hyperthyroidism, most likely Graves' disease. His free thyroxine level decreased in the first month after our examination. No increased vascularity of his thyroid gland was noted. The technetium uptake of his thyroid gland in scintigraphy was relatively increased compared to the intake of his salivary gland. We elected to observe rather than treat with anti-thyroid medications. CONCLUSION: We have to rule out spontaneous transient Graves' thyrotoxicosis when babies have symptoms of developmental delay and fail to thrive.