Clinical and genetic features of three patients
The male patient was 6 months old at first visit, he was born at full term, and the birth weight and length were unknown. He was born with micropenis, but his intelligence and growth development were normal. He had no special facial features, no abnormalities in heart, lungs and abdomen. The penis is 2.3 cm long and 1.2 cm in diameter. The urethral meatus is normal. The volume of bilateral testis is about 2 ml. The mother had a threatened miscarriage at two months of pregnancy, and she received progesterone treatment for one month. His father’s growth spurt was 17 years old, and his mother began menarche at age of 14–15 years old, and he had no family history of infertility.
The karyotype was 46, XY, and SRY was positive. Hormone levels were as follows: AMH > 23 ng/ml, INHB 126.2 pg/ml, T 434 ng dl after hCG stimulation test. LHRH stimulating test was performed in our hospital at the age of 3.5 years old. Basic LH 1.89 IU/L, FSH 5.48 IU/L, T < 20 ng/dl, peak LH/FSH = 3.47/5.48 = 0.63 > 0.6, suggesting that the pituitary has a response. MRI showed that pituitary, olfactory bulb, olfactory tract and olfactory sulcus were normal. Given the age of the patient, HH was suspected. He took testosterone undecanoate to treat micropenis for one month, then the penis was 4 cm long and 1.5 cm in diameter. The patient was followed up for 3.5 years. His hearing, smell and vision were normal, and fundus examination was normal. Later, a PANEL sequencing containing 167 gonads-associated genes was taken and found a pathogenic SOX2 varient from mother: c.695C > A/p.T232N, and an unreported pathogenic FGFR1 mutation from father: c.238C > T/p.R80C at the same time.
The male patient visited our clinic at the age of 2 years and 7 months. He was born at full term, with birth weight of 4 kg and a birth length of 51 cm. He was born with bilateral cryptorchidism, and had normal intelligence and growth development. Examination: eyes were normal; protruding ear, no inner cochlea, low nasal bridge, high arch bow, crooked mouth when crying, curved fifth finger, penetrating palm, but no abnormalities in heart, lungs and abdomen. The penis is 3 cm long and 1 cm in diameter. The urethral meatus is normal. The bilateral testis were located in the scrotum after surgery, and the volume was about 1 ml. No abnormalities during maternal pregnancy. The father was 172 cm, had a history of acrosomal enzyme deficiency, but the development was unknown. The mother was 170 cm, had menarche at the age of 15–16. She had one one elder sister aged 7 years, 123 cm tall, and had normal growth and development. The grandparents were consanguineous marriage. The father failed to have an IVF due to infertility, but the patient and his sister were born naturally.
The karyotype was 46, XY, and SRY was positive. Basic sex hormone levels at first visit were as follows: LH 0.12 IU / L, FSH 0.34 IU / L, T < 20 ng/dl, AMH 16.63 ng/ml, INHB 27.63 pg/ml, T 25 ng/dl after hCG prolonged test, which suggested testicular dysplasia. Now the child is 3 years and 2 months old, with normal intelligence, normal hearing, smell and vision, and no abnormalities in fundus examination. Genetic testing revealed that the patient carried both SOX2 mutation (c.695C > A/p.T232N, from mother, reported and pathogenic mutation) and CHD7 mutation (c.2656C > T/p.R886W, de novo, unreported and pathogenic mutation).
The male patient went to hospital because of micropenis, bilateral cryptorchidism and poor intellectural development at 5 months. Examination: sluggish face, flat pillow, flat nose, left ptosis, poor muscle strength at the back and neck, high palatal arch, decreased muscle strength of the limbs, fetal fat pad of two fingers. The penis was 1 cm long and 0.6 cm in diameter. The urethral opening was normal. Bilateral testes were located in the scrotum, the volume was about 1 ml. The patient was the first child after three gestation (one of the twins), and he was conceived through ovulation induction and artificial pregnancy. And he was born at full term, with birth weight of 3.1 kg. He could turn over at 7 months old, when he was 2 years and 8 months, he just could walk with one’s help, understand simple instructions, pronounce "Mom and Dad", speak unclearly, response slowly, and he received continuous rehabilitation training. At 6 months of pregnancy, the mother had a miscarriage due to abdominal pain, and the mother didn’t pregnant in next 4 years. The second pregnancy was through ovulation, but the fetus stopped developing at 2 months of pregnancy. The father had congenital scoliosis, and the development of puberty was unknown. The mother was 160 cm tall, the menarche was 13 years old, and she had polycystic ovary syndrome.
The karyotype of the patient was 46, XY, and SRY was positive. Basic hormone levels at 5 months were as follows: LH 1.4 IU/L, FSH 7.9 IU/L, T < 20 ng/dl, T 116 ng / dl after hCG stimulation test, AMH > 23 ng/ml, INHB: 74.5 pg/ml, IGF-1: 50.9 ng/ml, Peak LH/FSH = 2.59/7.9 = 0.33 < 0.6, after LHRH stimulation test, which suggested the pituitary gland could have a response. Thyroid function, ACTH and cortisol were normal. Pituitary MRI showed that the pituitary gland was normal, and the olfactory bulb, olfactory tract, and olfactory groove developed normally. The boy received testosterone undecanoate treatment for micropenis. The child was 3 years old nowadays, but he couldn’t walk steadily, catching up with mental and physical development, and is unstable. He was 88.3 cm tall, and 2 cm below the 3rd percentile of the growth curve. After treatment with testosterone undecanoate, the penis growed to 3.5 cm long and 1.1 cm in diameter. Hearing, smell and vision were normal, and no abnormalities were found on fundus examination. Genetic testing revealed that the patient harbored both SOX2 mutation (c.330C > A/p.Y110X, de novo, unreported and pathogenic mutation) and SEMA3A mutation (c.1432G > A/p.E478K, from mother, unreported, and clinical significance is uncertain).
In our single centre, more than 800 patients with 46, XY DSD received genetic tests, 118 patients were suspected with HH among these, and SOX2 gene mutation accounted for 2.5% of the 118 patients. Patient 1 showed only micropenis, without any deformity and mental and physical development disorders, while patient 2 carrying the same SOX2 gene mutation manifested with bilateral cryptorchidism and craniofacial deformities. Their mothers are carriers of SOX2 mutation, and both only show delayed menarche. Patient 3 showed micropenis, bilateral cryptorchidism, mental retardation, eye and craniofacial deformities, see Tables 1, 2 and Fig. 1 for details. Patient 1 and 2 carry the same reported pathogenic site mutation (p.T232N) of the SOX2 gene, which is located in the carboxy terminal transcription activation region, and Patient 3 carries a nonsense mutation (p.Y110X ), Close to the HMG region, which has not been reported in the literature, but there are reports of the same site missense pathogenic mutation (p.Y110C). Intersting, we found that all three cases carry another gene varient that caused HH meanwhile, see Fig. 1 for the combined gene mutation.
Literature summary and comparison with our patients
In 2003, the SOX2 gene mutation was first reported in patients with A/M deformities. Up to now, a total of 123 cases have been reported, including male (57/109, 52.3%) and female (52/109, 47.7%), some are not provided, visiting age ranges from fetus to 65 years old, 43.9% (25/57) male patients showed genital abnormalities, see supplementary table 1 and Table 3. Almost all patients choose to ophthalmology clinic, except for those patients without major eye deformities. While all three patients in our study are male, and show no major ocular symptoms.
Among those patients, 91.1% of patients have major ocular deformities. All patients reported whose variants inherit from parents, 15.1% parents (including mother 11.0% and father 4.1%) show completely normal phenotypes, 4.1% (3/73) variants inherit from mother with germinal mosaicism. Among the extraocular symptoms, the most common is developmental delay/mental retardation (DD/MR), accounting for 40.7%, followed by brain anomely (BA), accounting for 28.5%, motor development delay (MD) for 22%, male genital abnormalities (GA, including micropenis, cryptorchidism and hypospadias) for 20.3%, short stature (SS) for 17.1%, facial dysmorphism (FD) accounting for 12.2%, non-syndromic HH accounted for 4.9%, including three male patients (2.4%). Clinical and genetic features of all patients without major ocular deformities were listed in Table 4. The three patients in the study were mainly genital abnormalities, left ptosis, hypotonia, short stature, and intellectual impairment, but with no major ocular abnormalities. No seizures were found.
By analyzing all reported mutations of SOX2, mutational types include frameshift (39.4%), deletion (22%), nonsense (19.7%), missense (18.9%), 71.2% (53/73) of those are de novo, 15.1% (11/73) cases inherit from mother (11.0%) or father (4.1%) with completely normal phenotypes, 4.1% (3/73) variants inherit from mother with germinal mosaicism but normal phenotypes, and 5.5% (4/73) variants from their parents manifested with abnormal syndromes, including one farther with ocular deformity, one mother with HH. And in our three patients, mutations of patients 2 and 3 are de novo, and mutation of patient 1 inherited from mother with normal phenotypes.