Diabetes mellitus with severe insulin resistance in a young male patient with a heterozygous pathogenic IRS1 frameshift variant.

We present the case of a young male patient (height, 158.1 cm [+3.3 standard deviation (SD)]; weight, 63.7 kg [body mass index, 25.5]) with diabetes mellitus and severe insulin resistance associated with a heterozygous pathogenic insulin receptor substrate 1 (IRS1) frameshift mutation. The patient also had severe acanthosis nigricans. Notably, the patient's father was undergoing treatment with high doses of insulin for diabetes mellitus, and had been experiencing angina pectoris. Laboratory data showed a fasting plasma glucose level of 88 mg/dL, hemoglobin A1C (HbA1c) of 7.4%, fasting insulin level of 43.1 µg/mL, and a homeostasis model assessment-insulin resistance (HOMA-IR) score of 9.36, indicating hyperinsulinism. Oral glucose tolerance test revealed a diabetic pattern and insulin hypersecretion. In addition, the patient had hyperlipidemia. Genetic studies revealed a heterozygous frameshift variant of IRS1 [NM_005544.3:c.1791dupG:p.(His598Alafs*13)] in the patient and his father, which can impair the binding and activation of phosphoinositide 3 (PI-3) kinase and defectively mediate the translocation of glucose transporter type 4 (GLUT4) in adipose tissues, possibly leading to glucose intolerance. Therefore, this variant may be disease causing. After confirming IRS1 mutation, metformin was administered, and physical exercise and dietary management were initiated; metformin was well tolerated, and optimal glycemic control was maintained.

A novel GNAS-Gsα splice donor site variant in a girl with pseudohypoparathyroidism type 1A and her mother with pseudopseudohypoparathyroidism.

We encountered a Chinese girl with pseudohypoparathyroidism type 1A (PHP1A) and her mother with pseudopseudohypoparathyroidism (PPHP). Sequencing analysis of GNAS-Gsα revealed a heterozygous c.212+2T>C variant (NM_000516.4) affecting the canonical splice donor site of intron 2 in the girl and her mother. RT-PCR performed on mRNA samples obtained from cycloheximide-treated and cycloheximide-untreated lymphoblastoid cell lines of this girl revealed the utilization of an alternative splice donor site at 33-34 bp from the boundary between exon 2 and intron 2 and the production of an aberrant mRNA with a retention of a 32 bp intronic sequence between exon 2 and exon 3 (p.(Gly72Lysfs*39)), which satisfied the condition for the occurrence of nonsense-mediated mRNA decay, as predicted by SpliceAI. This study revealed the molecular consequences of disruption of the canonical splice donor site and confirmed the clinical utility of SpliceAI.

Surgery for long tubular intestinal duplication with massive hemorrhage: a case report and literature review.

BACKGROUND: Long tubular duplication is a rare congenital intestinal disease, that can lead to emergency situations marked by massive hemorrhage. However, preoperative diagnosis and surgical treatment are challenging. This report presents preoperative images and details a surgical procedure for long tubular intestinal duplications with massive hemorrhage. CASE PRESENTATION: A 3-year-old boy presented to the emergency department with melena. Despite undergoing a Tc-99m pertechnetate scintigraphy one year prior, which revealed nonspecific findings with enhancement of some parts of the intestine, enhanced abdominal CT revealed an edematous small intestine with luminal extravasation. The patient received a transfusion of red blood cells; however, his hemoglobin level did not improve. Arterial angiography and double-balloon endoscopy revealed no remarkable findings. Exploratory laparotomy revealed a long tubular duplication in half of the small intestine. Utilizing the Wrenn procedure, we successfully removed all duplicate mucosa. Pathological findings showed that almost all duplications contained gastric mucosa and revealed an ulcer with a ruptured arterial vessel. His symptoms were resolved, and the hemoglobin level stabilized. At 2 months postoperatively, no surgical complications were present. CONCLUSIONS: Effective management of long tubular duplications with massive hemorrhage involves timely application of the Wrenn procedure. Recognition of specific imaging findings is crucial to prompt exploratory laparotomy, ensuring optimal outcomes and preventing delays in treatment.

Sotos syndrome with marked overgrowth in three Japanese patients with heterozygous likely pathogenic NSD1 variants: case reports with review of literature.

We report three Japanese patients with Sotos syndrome accompanied by marked overgrowth, i.e., a 2 8/12-year-old boy with a height of 105.2 cm (+4.4 SD) (patient 1), the mother of patient 1 with a height of 180.8 cm (+4.1 SD) (patient 2), and a 12 10/12-year-old girl with a height of 189.4 cm (+6.3 SD) (patient 3). In addition to the marked overgrowth (tall stature), patients 1-3 exhibited Sotos syndrome-compatible macrocephaly and characteristic features, whereas intellectual and developmental disabilities remained at a borderline level in patient 1 and were apparently absent from patients 2 and 3. Thus, whole exome sequencing was performed to confirm the diagnosis, revealing a likely pathogenic c.6356A>G:p.(Asp2119Gly) variant in NSD1 of patients 1 and 2, and a likely pathogenic c.6599dupT:p.(Ser2201Valfs*4) variant in NSD1 of patient 3 (NM_022455.5). The results, in conjunction with the previously reported data in nine patients with marked overgrowth (≥4.0 SD), imply that several patients with Sotos syndrome have extreme tall stature even in adulthood. Thus, it is recommended to examine NSD1 in patients with marked overgrowth as the salient feature.

Serum steroid metabolite profiling by LC-MS/MS in two phenotypic male patients with HSD17B3 deficiency: Implications for hormonal diagnosis.

Although 17ß-hydroxysteroid dehydrogenase type 3 (HSD17B3) deficiency is diagnosed when a testosterone/androstenedione (T/A-dione) ratio after human chorionic gonadotropin (hCG) stimulation is below 0.8, this cut-off value is primarily based on hormonal data measured by conventional immunoassay (IA) in patients with feminized or ambiguous genitalia. We examined two 46,XY Japanese patients with undermasculinized genitalia including hypospadias (patient 1 and patient 2). Endocrine studies by IA showed well increased serum T value after hCG stimulation (2.91 ng/mL) and a high T/A-dione ratio (4.04) in patient 1 at 2 weeks of age and sufficiently elevated basal serum T value (2.60 ng/mL) in patient 2 at 1.5 months of age. Despite such partial androgen insensitivity syndrome-like findings, whole exome sequencing identified biallelic ″pathogenic″ or ″likely pathogenic″ variants in HSD17B3 (c .188 C>T:p.(Ala63Val) and c .194 C>T:p.(Ser65Leu) in patient 1, and c.139 A>G:p.(Met47Val) and c.672 + 1 G>A in patient 2) (NM_000197.2), and functional analysis revealed reduced HSD17B3 activities of the missense variants (∼ 43% for p.Met47Val, ∼ 14% for p.Ala63Val, and ∼ 0% for p.Ser65Leu). Thus, we investigated hCG-stimulated serum steroid metabolite profiles by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in patient 1 at 7 months of age and in patient 2 at 11 months of age as well as in five control males with idiopathic micropenis aged 1 - 8 years, and found markedly high T/A-dione ratios (12.3 in patient 1 and 5.4 in patient 2) which were, however, obviously lower than those in the control boys (25.3 - 56.1) and sufficiently increased T values comparable to those of control males. The elevated T/A-dione ratios are considered be due to the residual HSD17B3 function and the measurement by LC-MS/MS. Thus, it is recommended to establish the cut-off value for the T/A-dione ratio according to the phenotypic sex reflecting the residual function and the measurement method.

Microdeletion at ESR1 Intron 6 (DEL_6_75504) Is a Susceptibility Factor for Cryptorchidism and Hypospadias.

CONTEXT: We have previously reported that a specific "AGATC" haplotype in a >34 kb tight linkage disequilibrium (LD) block within ESR1 is strongly associated with cryptorchidism and hypospadias in Japanese boys. OBJECTIVE: We aimed to determine the true susceptibility factor for cryptorchidism and hypospadias linked to the "AGATC" haplotype. METHODS: We performed various molecular studies in hitherto unreported 230 Italian boys (80 with cryptorchidism and 150 with normal genitalia) and previously reported and newly recruited 415 Japanese boys (149 with cryptorchidism, 141 with hypospadias, and 125 with normal genitalia). We also performed ESR1 expression analyses using breast cancer-derived MCF-7 cells. RESULTS: Haplotype analysis revealed the LD block and positive association of the "AGATC" haplotype with cryptorchidism in Italian boys. Whole genome sequencing identified an identical 2249-bp microdeletion (ΔESR1) generated by a microhomology-mediated replication error in both Japanese and Italian boys with the specific haplotype. ΔESR1 was found to be strongly associated with cryptorchidism and hypospadias by Cochran-Armitage trend test and was revealed to show nearly absolute LD with the "AGATC" haplotype. ESR1 expression was upregulated in MCF-7 cells with a homozygous deletion encompassing ΔESR1 and those with a homozygous deletion involving a CTCF-binding site within ΔESR1. CONCLUSION: The results reveal that ΔESR1, which has been registered as "DEL_6_75504" in gnomAD SVs v2.1, is the true susceptibility factor for cryptorchidism and hypospadias. It appears that ΔESR1 was produced in a single ancestral founder of modern humans and has been maintained within the genome of multiple ethnic groups by selection.

Clinical and molecular findings in three Japanese patients with N-acetylneuraminic acid synthetase-congenital disorder of glycosylation (NANS-CDG).

We report clinical and molecular findings in three Japanese patients with N-acetylneuraminic acid synthetase-congenital disorder of glycosylation (NANS-CDG). Patient 1 exhibited a unique constellation of clinical features including marked hydrocephalus, spondyloepimetaphyseal dysplasia (SEMD), and thrombocytopenia which is comparable to that of an infant reported by Faye-Peterson et al., whereas patients 2 and 3 showed Camera-Genevieve type SMED with intellectual/developmental disability which is currently known as the sole disease name for NANS-CDG. Molecular studies revealed a maternally inherited likely pathogenic c.207del:p.(Arg69Serfs*57) variant and a paternally derived likely pathogenic c.979_981dup:p.(Ile327dup) variant in patient 1, a homozygous likely pathogenic c.979_981dup:p.(Ile327dup) variant caused by maternal segmental isodisomy involving NANS in patient 2, and a paternally inherited pathogenic c.133-12T>A variant leading to aberrant splicing and a maternally inherited likely pathogenic c.607T>C:p.(Tyr203His) variant in patient 3 (reference mRNA: NM_018946.4). The results, together with previously reported data, imply that (1) NANS plays an important role in postnatal growth and fetal brain development; (2) SMED is recognizable at birth and shows remarkable postnatal evolution; (3) NANS-CDG is associated with low-normal serum sialic acid, obviously elevated urine N-acetylmannosamine, and normal N- and O-glycosylation of serum proteins; and (4) NANS-CDG is divided into Camera-Genevieve type and more severe Faye-Peterson type.

Combined pituitary hormone deficiency in a patient with an FGFR1 missense variant: case report and literature review.

Recent studies have indicated that heterozygous loss-of-function variants in fibroblast growth factor receptor 1 (FGFR1) are involved in the development of congenital hypogonadotropic hypogonadism and combined pituitary hormone deficiency (CPHD). We encountered a Japanese boy with short stature and pubertal failure. Endocrine studies showed GH, TSH, and LH/FSH deficiencies, and brain magnetic resonance imaging delineated hypoplastic anterior pituitary and ectopic posterior pituitary. The patient was treated with GH, l-thyroxine, and hCG/rFSH. Next-generation sequencing panel for pituitary dysfunction identified a probably weak disease-associated heterozygous missense variant in FGFR1 (NM_023110.3:c.176A>T:p.(Asp59Val)), together with a probably non-deleterious heterozygous missense variant in KISS1R (NM_032551.5:c.769G>C:p.(Val257Leu)). We also review six previously reported CHPD patients with probably deleterious FGFR1 variants. The data, in conjunction with the previously reported cases, argue for the relevance of FGFR1 variants to the development of CPHD.

ACAN biallelic variants in a girl with severe idiopathic short stature.

Although ACAN heterozygous loss-of-function variants often cause idiopathic short stature (ISS) phenotype, there is no report describing ISS phenotype caused by ACAN biallelic loss-of-function variants. We encountered a 4 1/12-year-old Japanese girl with a height of 80.4 cm (-5.2 SD), a weight of 11.4 kg (-1.9 SD), a head circumference of 48.7 cm (-0.6 SD), and an arm span/height ratio of 1.0 (+1.1 SD). Endocrine studies and bone survey showed no abnormal findings. Whole exome sequencing revealed biallelic rare variants in ACAN, i.e., NM_013227.4:c.4214delC:p.(Pro1405Leufs*3) derived from her father and paternal grandfather with short stature (-2.9 and -2.0 SD, respectively) and NM_013227.4:c.7124 A>G:p.(Gln2375Arg) inherited from her mother and maternal grandmother with short stature (-2.1 and -3.0 SD, respectively). The frameshift variant underwent nonsense mediated mRNA decay, and the missense variant was assessed to have high pathogenicity. The results imply for the first time that ACAN biallelic loss-of-function variants can cause severe ISS phenotype.

Retrotransposition disrupting EBP in a girl and her mother with X-linked dominant chondrodysplasia punctata.

X-linked dominant chondrodysplasia punctata (CDPX2) is a rare congenital disorder caused by pathogenic variants in EBP on Xp11.23. We encountered a girl and her mother with CDPX2-compatible phenotypes including punctiform calcification in the neonatal period of the girl, and asymmetric limb shortening and ichthyosis following the Blaschko lines in both subjects. Although Sanger direct sequencing failed to reveal a disease-causing variant in EBP, whole genome sequencing (WGS) followed by Manta analysis identified a ~ 4.5 kb insertion at EBP exon 2 of both subjects. The insertion was associated with the hallmarks of retrotransposition such as an antisense poly(A) tail, a target site duplication, and a consensus endonuclease cleavage site, and the inserted sequence harbored full-length SVA_F1 element with 5'- and 3'-transductions containing the Alu sequence. The results imply the relevance of retrotransposition to the human genetic diseases and the usefulness of WGS in the identification of retrotransposition.

Novel ALG12 variants and hydronephrosis in siblings with impaired N-glycosylation.

BACKGROUND: ALG12-CDG is a rare autosomal recessive type I congenital disorder of glycosylation (CDG) due to pathogenic variants in ALG12 which encodes the dolichyl-P-mannose:Man-7-GlcNAc-2-PP-dolichyl-alpha-6-mannosyltransferase. Thirteen patients from unrelated 11 families have been reported, most of them result in broad multisystem manifestations with clinical variability. It is important to validate abnormal glycosylation to establish causal relationship. CASE REPORT: Here, we report two siblings with novel compound heterozygous variants in ALG12: c.443T>C, p.(Leu148Pro) and c.412_413insCGT, p.(Gln137_Phe138insSer). Both patients showed global developmental delay, microcephaly, hypotonia, failure to thrive, facial dysmorphism, skeletal malformations and coagulation abnormalities, which are common in ALG12-CDG. In addition, one of our patients showed left hydronephrosis, which is a novel clinical feature in ALG12-CDG. Brain MRI showed hypoplasia of cerebrum, brain stem and cerebellar vermis in both patients. N-glycosylation defects of trypsin digested transferrin peptides were revealed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), and electrospray ionization MS verified the lack of N-glycans in transferrin. CONCLUSIONS: The present study can add hydronephrosis to phenotypic spectrum of ALG12-CDG. Since the symptoms of ALG12-CDG are quite diverse, the combination of whole-exome sequencing and transferrin glycopeptide analysis with MS, can help diagnosis of ALG12-CDG.

Global developmental delay, systemic dysmorphism and epilepsy in a patient with a de novo U2AF2 variant.

U2 small nuclear RNA auxiliary factor 2 (U2AF2) is an essential pre-mRNA splicing factor in an early step of splicing. Alternative splicing plays an important role in neuronal development, and disorders of RNA processing steps are implicated in neurological disorders. Recently, the large trio whole-exome sequencing study reported U2AF2 as a novel gene significantly associated with developmental disorders: however, the clinical details of patients with U2AF2 variants were not available. Here, we report an individual with a de novo U2AF2 variant (c.445C>T, p.(Arg149Trp)) using trio-based whole-exome sequencing. This residue was positioned in the RNA recognition motif 1 which recognizes a polypyrimidine-tract splice site signal. The patient showed global developmental delay, intellectual disability, epilepsy, short stature, microcephaly, facial dysmorphism, intermittent exotropia, bilateral ptosis, muscle hypotonia and thin corpus callosum, indicating that U2AF2-related disorder could include systemic dysmorphisms, epilepsy and brain malformation along with global developmental delay.

Parthenogenetic mosaicism: generation via second polar body retention and unmasking of a likely causative PER2 variant for hypersomnia.

BACKGROUND: Parthenogenetic mosaicism is an extremely rare condition identified only in five subjects to date. The previous studies indicate that this condition is mediated by parthenogenetic activation and is free from a specific phenotype ascribed to unmaking of a maternally inherited recessive variant in the parthenogenetic cell lineage. RESULTS: We examined a 28-year-old Japanese 46,XX female with Silver-Russell syndrome and idiopathic hypersomnia. The results revealed (1) predominance of maternally derived alleles for all the differentially methylated regions examined; (2) no disease-related copy-number variant; (3) two types of regions for all chromosomes, i.e., four BAF (B-allele frequency) band regions with single major microsatellite peaks of maternal origin and single minor microsatellite peaks of non-maternal (paternal) origin, and six BAF band regions with single major microsatellite peaks of maternal origin and two minor microsatellite peaks of maternal and non-maternal (paternal) origin; (4) an unmasked extremely rare PER2 variant (c.1403G>A:p.(Arg468Gln)) with high predicted pathogenicity; (5) mildly affected local structure with altered hydrogen bonds of the p.Arg468Gln-PER2 protein; and (6) nucleus-dominant subcellular distribution of the p.Arg468Gln-PER2 protein. CONCLUSIONS: The above findings imply that the second polar body retention occurred around fertilization, resulting in the generation of the parthenogenetic cell lineage by endoreplication of a female pronucleus and the normal cell lineage by fusion of male and female pronuclei, and that the homozygous PER2 variant in the parthenogenetic cells is the likely causative factor for idiopathic hypersomnia.

Genetic and phenotypic analysis of 101 patients with developmental delay or intellectual disability using whole-exome sequencing.

Whole-exome sequencing (WES) enables identification of pathogenic variants, including copy number variants (CNVs). In this study, we performed WES in 101 Japanese patients with unexplained developmental delay (DD) or intellectual disability (ID) (63 males and 38 females), 98 of them with trio-WES. Pathogenic variants were identified in 54 cases (53.5%), including four cases with pathogenic CNVs. In one case, a pathogenic variant was identified by reanalysis of exome data; and in two cases, two molecular diagnoses were identified. Among 58 pathogenic variants, 49 variants occurred de novo in 48 patients, including two somatic variants. The accompanying autism spectrum disorder and external ear anomalies were associated with detection of pathogenic variants with odds ratios of 11.88 (95% confidence interval [CI] 2.52-56.00) and 3.46 (95% CI 1.23-9.73), respectively. These findings revealed the importance of reanalysis of WES data and detection of CNVs and somatic variants in increasing the diagnostic yield for unexplained DD/ID. In addition, genetic testing is recommended when patients suffer from the autism spectrum disorder or external ear anomalies, which potentially suggests the involvement of genetic factors associated with gene expression regulation.

Primary ovarian insufficiency in a female with phosphomannomutase-2 gene (PMM2) mutations for congenital disorder of glycosylation.

Primary ovarian insufficiency (POI) is a highly heterogeneous condition, and its underlying causes remain to be clarified in a large fraction of patients. Congenital disorders of glycosylation (CDG) are multisystem diseases caused by mutations of a number of genes involved in N-glycosylation or O-glycosylation, and the most frequent form is PMM2-CDG (alias, CDG-Ia) resulting from biallelic mutations in PMM2 encoding phosphomannomutase-2 involved in N-glycosylation. Here, we examined a 46,XX Japanese female with syndromic POI accompanied by an undetectable level of serum anti-Müllerian hormone (AMH). Whole exome sequencing identified biallelic pathogenic mutations of PMM2 (a novel c.34G>C:p.(Asp12His) of maternal origin and a recurrent c.310C>G:p.(Leu104Val) of paternal origin) (NM_000303.3), and N-glycosylation studies detected asialotransferrin and disialotransferrin characteristic of PMM2-CDG, in addition to normally glycosylated tetrasialotransferrin. Clinical assessment showed cerebellar hypotrophy, which is a fairly characteristic and highly prevalent feature in PMM2-CDG, together with multiple non-specific features reported in PMM2-CDG such as characteristic face, intellectual disability, skeletal abnormalities, and low blood antithrombin III value. These results including the undetectable level of serum AMH, in conjunction with previously reported findings suggestive of the critical role of glycosylation in oocyte development and function, imply that PMM2-CDG almost invariably leads to POI primarily because of the defective oogenesis and/or oocyte-dependent early folliculogenesis rather than the compromised bioactivity of FSH/LH with defective glycosylation. Thus, it is recommended to examine PMM2 in patients with syndromic POI, especially in those with cerebellar ataxia/hypotrophy.

Insulin resistant diabetes mellitus in SHORT syndrome: case report and literature review.

SHORT syndrome is a rare developmental disorder frequently associated with growth failure and insulin resistant diabetes mellitus (IRDM). Since GH has a diabetogenic effect, GH therapy has been regarded as a contraindication. We observed a Brazilian girl with SHORT syndrome who received GH therapy from 4 6/12 years of age for SGA short stature. GH dosage was increased from 0.23 to 0.36 mg/kg/week, but statural response to GH therapy remained poor. Her blood HbA1c level, though it remained 5.5-6.0% in childhood, began to elevate with puberty and increased to 9.2% at 10 6/12 years of age, despite the discontinuation of GH therapy at 9 11/12 years of age. Laboratory studies indicated antibody-negative IRDM. She was treated with metformin and canagliflozin (a sodium glucose co-transporter 2 (SGLT2) inhibitor), which ameliorated overt diurnal hyperglycemia and mild nocturnal hypoglycemia and reduced her blood HbA1c around 7%. Whole exome sequencing revealed a de novo heterozygous pathogenic variant (c.1945C>T:p.(Arg649Trp)) in PIK3R1 known as the sole causative gene for SHORT syndrome. Subsequent literature review for patients with molecularly confirmed SHORT syndrome revealed the development of IRDM in 10 of 15 GH-untreated patients aged ≥12 years but in none of three GH-treated and six GH-untreated patients aged ≤10 years. These findings imply a critical role of pubertal development and/or advanced age rather than GH therapy in the development of IRDM, and a usefulness of SGLT2 inhibitor in the treatment of IRDM.

Kagami-Ogata syndrome in a patient with 46,XX,t(2;14)(q11.2;q32.2)mat disrupting MEG3.

Kagami-Ogata syndrome (KOS14) is a rare imprinting disorder characterized by a unique constellation of phenotypes including bell-shaped small thorax with coat-hanger appearance of the ribs. We encountered an African American female infant with KOS14 phenotype and 46,XX,t(2;14)(q11.2;q32.2)mat. After excluding upd(14)pat and an epimutation (hypermethylation) and a deletion affecting the maternally derived 14q32.2 imprinted region, we performed whole-genome sequencing, revealing that the translocation was generated between noncoding region at 2q11.2 and intron 6 of MEG3 at 14q32.2. Subsequent Sanger sequencing for the fusion points showed that the chromosomal fusion on the der(2) chromosome occurred between Chr2:102,193,994 (bp) and Chr14:101,314,628 (bp) in association with an insertion of 5-bp segment of unknown origin and that on the der(14) chromosome took place between Chr14:101,314,627 (bp) and Chr2:102,193,995 (bp) in association with an insertion of 1-bp segment of unknown origin (according to GRCh37/hg19). The results, together with the previous data in patients with KOS14, imply that the MEG3 disruption by 46,XX,t(2;14)(q11.2;q32.2)mat caused silencing of all MEGs including RTL1as and resultant excessive RTL1 expression, leading to the development of KOS14. To our knowledge, while Robertsonian translocations involving chromosome 14 have been reported in KOS14, this is the first case of KOS14 caused by a chromosomal translocation involving the 14q32.2 imprinted region.

Nonsense-associated altered splicing of MAP3K1 in two siblings with 46,XY disorders of sex development.

Although splicing errors due to single nucleotide variants represent a common cause of monogenic disorders, only a few variants have been shown to create new splice sites in exons. Here, we report an MAP3K1 splice variant identified in two siblings with 46,XY disorder of sex development. The patients carried a maternally derived c.2254C>T variant. The variant was initially recognized as a nonsense substitution leading to nonsense-mediated mRNA decay (p.Gln752Ter); however, RT-PCR for lymphoblastoid cell lines showed that this variant created a new splice donor site and caused 39 amino acid deletion (p.Gln752_Arg790del). All transcripts from the variant allele appeared to undergo altered splicing. The two patients exhibited undermasculinized genitalia with and without hypergonadotropism. Testosterone enanthate injections and dihydrotestosterone ointment applications yielded only slight increase in their penile length. Dihydrotestosterone-induced APOD transactivation was less significant in patients' genital skin fibroblasts compared with that in control samples. This study provides an example of nonsense-associated altered splicing, in which a highly potent exonic splice site was created. Furthermore, our data, in conjunction with the previous data indicating the association between MAP3K1 and androgen receptor signaling, imply that the combination of testicular dysgenesis and androgen insensitivity may be a unique phenotype of MAP3K1 abnormalities.

TSC1 intragenic deletion transmitted from a mosaic father to two siblings with cardiac rhabdomyomas: Identification of two aberrant transcripts.

Tuberous sclerosis complex (TSC) is a rare autosomal dominant disorder characterized by non-cancerous tumors in multiple organs including the brain, kidney, lung, heart, and skin. We encountered a Japanese family consisting of two siblings (a four-year-old boy and a one-year-old girl) with multiple cardiac rhabdomyomas conveying a high risk of TSC and apparently unaffected sibling (a two-year-old girl) and parents. Whole exome sequencing and application of Integrative Genomic Viewer revealed an identical intragenic TSC1 deletion with the breakpoints on intron 15 and exon 19 in the affected siblings, but not in the apparently unaffected sibling and parents. Subsequently, PCR-based analyses were performed using primers flanking the deletion, showing that the deletion was also present in the father and that the deletion occurred between chr9:135,777,038 (bp) and chr9:135,780,540 (bp) in association with a one bp overlap. Furthermore, RT-PCR analyses were carried out using lymphoblastoid cell lines, revealing a major in-frame insertion/deletion transcript produced by aberrant splicing using a cryptic ″ag″ splice acceptor motif at intron 15 (r.1998_2438delinsTTCATTAGGTGG) and a minor frameshift transcript generated by aberrant splicing between exon 15 and exon 20 (r.1998_2502del, p.Lys666Asnfs*15) in the affected siblings. These findings imply that the intragenic deletion producing two aberrant transcripts was generated as a somatic pathogenic variant involving the germline in the father and was transmitted to the affected siblings.

IGF2 Mutations.

OBJECTIVE: IGF2 is a paternally expressed growth-promoting gene. Here, we report five cases with IGF2 mutations and review IGF2 mutation-positive patients described in the literature. We also compare clinical features between patients with IGF2 mutations and those with H19/IGF2:IG-DMR epimutations. RESULTS: We recruited five cases with IGF2 mutations: case 1 with a splice site mutation (c.-6-1G>C) leading to skipping of exon 2 and cases 2-5 with different missense mutations (p.(Cys70Tyr), p.(Cys71Arg), p.(Cys33Ser), and p.(Cys45Ser)) affecting cysteine residues involved in the S-S bindings. All the mutations resided on the paternally inherited allele, and the mutation of case 5 was present in a mosaic condition. Clinical assessment revealed Silver-Russell syndrome (SRS) phenotype with Netchine-Harbison scores of ≥5/6 in all the apparently nonmosaic 14 patients with IGF2 mutations (cases 1-4 described in this study and 10 patients reported in the literature). Furthermore, compared with H19/IGF2:IG-DMR epimutations, IGF2 mutations were associated with low frequency of hemihypoplasia, high frequency of feeding difficulty and/or reduced body mass index, and mild degree of relative macrocephaly, together with occasional development of severe limb malformations, high frequency of cardiovascular anomalies and developmental delay, and low serum IGF-II values. CONCLUSIONS: This study indicates that IGF2 mutations constitute a rare but important cause of SRS. Furthermore, while both IGF2 mutations and H19/IGF2:IG-DMR epimutations lead to SRS, a certain degree of phenotypic difference is observed between the two groups, probably due to the different IGF2 expression pattern in target tissues.