Should 45,X/46,XY boys with no or mild anomaly of external genitalia be investigated and followed up?

OBJECTIVE: Few studies of patients with a 45,X/46,XY mosaicism have considered those with normal male phenotype. The purpose of this study was to evaluate the clinical outcome of 45,X/46,XY boys born with normal or minor abnormalities of external genitalia, notably in terms of growth and pubertal development. METHODS: Retrospective longitudinal study of 40 patients followed between 1982 and 2017 in France. RESULTS: Twenty patients had a prenatal diagnosis, whereas 20 patients had a postnatal diagnosis, mainly for short stature. Most patients had stunted growth, with abnormal growth spurt during puberty and a mean adult height of 158 ± 7.6 cm, i.e. -2.3 DS with correction for target height. Seventy percent of patients presented Turner-like syndrome features including cardiac (6/23 patients investigated) and renal malformations (3/19 patients investigated). Twenty-two patients had minor abnormalities of external genitalia. One patient developed a testicular embryonic carcinoma, suggesting evidence of partial gonadal dysgenesis. Moreover, puberty occurred spontaneously in 93% of patients but 71% (n = 5) of those evaluated at the end of puberty presented signs of declined Sertoli cell function (low inhibin B levels and increased FSH levels). CONCLUSION: This study emphasizes the need to identify and follow-up 45,X/46,XY patients born with normal male phenotype until adulthood, as they present similar prognosis than those born with severe genital anomalies. Currently, most patients are diagnosed in adulthood with azoospermia, consistent with our observations of decreased testicular function at the end of puberty. Early management of these patients may lead to fertility preservation strategies.

Chromosome 14q32.2 Imprinted Region Disruption as an Alternative Molecular Diagnosis of Silver-Russell Syndrome.

Context: Silver-Russell syndrome (SRS) (mainly secondary to 11p15 molecular disruption) and Temple syndrome (TS) (secondary to 14q32.2 molecular disruption) are imprinting disorders with phenotypic (prenatal and postnatal growth retardation, early feeding difficulties) and molecular overlap. Objective: To describe the clinical overlap between SRS and TS and extensively study the molecular aspects of TS. Patients: We retrospectively collected data on 28 patients with disruption of the 14q32.2 imprinted region, identified in our center, and performed extensive molecular analysis. Results: Seventeen (60.7%) patients showed loss of methylation of the MEG3/DLK1 intergenic differentially methylated region by epimutation. Eight (28.6%) patients had maternal uniparental disomy of chromosome 14 and three (10.7%) had a paternal deletion in 14q32.2. Most patients (72.7%) had a Netchine-Harbison SRS clinical scoring system ≥4/6, and consistent with a clinical diagnosis of SRS. The mean age at puberty onset was 7.2 years in girls and 9.6 years in boys; 37.5% had premature pubarche. The body mass index of all patients increased before pubarche and/or the onset of puberty. Multilocus analysis identified multiple methylation defects in 58.8% of patients. We identified four potentially damaging genetic variants in genes encoding proteins involved in the establishment or maintenance of DNA methylation. Conclusions: Most patients with 14q32.2 disruption fulfill the criteria for a clinical diagnosis of SRS. These clinical data suggest similar management of patients with TS and SRS, with special attention to their young age at the onset of puberty and early increase of body mass index.

Retinal involvement in two unrelated patients with Myhre syndrome.

Myhre syndrome is a very rare condition described thirty years ago and related to mutations in the SMAD4 gene. It has been reported in 19 patients, including 13 males and 6 females before the recent finding of heterozygous mutations in the SMAD4 gene in 19 patients. It is characterized by mental retardation, short stature, muscle hypertrophy, limitation of joints movements, deafness, skeletal anomalies, and facial dysmorphism. Ophthalmological involvement includes hypermetropia and congenital cataract. We report here the new finding of retinal involvement including retinitis pigmentosa and maculopathy in two unrelated patients with Myhre syndrome. The patient with retinitis pigmentosa carried the p.I500T mutation in SMAD4, but no mutation was found in the patient with the maculopathy.

SEMA3A deletion in a family with Kallmann syndrome validates the role of semaphorin 3A in human puberty and olfactory system development.

BACKGROUND: Kallmann syndrome (KS) is a genetic disorder associating pubertal failure with congenitally absent or impaired sense of smell. KS is related to defective neuronal development affecting both the migration of olfactory nerve endings and GnRH neurons. The discovery of several genetic mutations responsible for KS led to the identification of signaling pathways involved in these processes, but the mutations so far identified account for only 30% of cases of KS. Here, we attempted to identify new genes responsible for KS by using a pan-genomic approach. METHODS: From a cohort of 120 KS patients, we selected 48 propositi with no mutations in known KS genes. They were analyzed by comparative genomic hybridization array, using Agilent 105K oligonucleotide chips with a mean resolution of 50 kb. RESULTS: One propositus was found to have a heterozygous deletion of 213 kb at locus 7q21.11, confirmed by real-time qPCR, deleting 11 of the 17 SEMA3A exons. This deletion cosegregated in the propositus' family with the KS phenotype, that was transmitted in autosomal dominant fashion and was not associated with other neurological or non-neurological clinical disorders. SEMA3A codes for semaphorin 3A, a protein that interacts with neuropilins. Mice lacking semaphorin 3A expression have been showed to have a Kallmann-like phenotype. CONCLUSIONS: SEMA3A is therefore a new gene whose loss-of-function is involved in KS. These findings validate the specific role of semaphorin 3A in the development of the olfactory system and in neuronal control of puberty in humans.

Delineation of late onset hypoventilation associated with hypothalamic dysfunction syndrome.

Late Onset Central Hypoventilation Syndrome associated with Hypothalamic Dysfunction (LO-CHS/HD) is a distinct entity among the clinical and genetic heterogeneous group of patients with late onset central hypoventilation. Here we report a series of 13 patients with LO-CHS/HD. Rapid onset obesity is the first symptom of HD followed by hypoventilation with a mean delay of 18 mos. The outcome remains poor for this group of patients and would benefit from early diagnosis to anticipate ventilation and possible metabolic disorders. Tumor predisposition is more frequent than initially suspected and as high as 40% in this series. These tumors of the sympathetic nervous system (TSNS) are usually differentiated and do not significantly worsen the prognosis. We report a familial case with recurrence in siblings. The cause underlying LO-CHS/HD remains poorly understood although recurrence in siblings argues for a monogenic disorder. We ruled out PHOX2B, ASCL1, and NECDIN as disease-causing genes by direct sequencing in our series of patients and discuss possible disease-causing mechanisms.

11p15 imprinting center region 1 loss of methylation is a common and specific cause of typical Russell-Silver syndrome: clinical scoring system and epigenetic-phenotypic correlations.

CONTEXT: Russell-Silver syndrome (RSS), characterized by intrauterine and postnatal growth retardation, dysmorphic features, and frequent body asymmetry, spares cranial growth. Maternal uniparental disomy for chromosome 7 (mUPD7) is found in 5-10% of cases. We identified loss of methylation (LOM) of 11p15 Imprinting Center Region 1 (ICR1) domain (including IGF-II) as a mechanism leading to RSS. OBJECTIVE: The aim was to screen for 11p15 epimutation and mUPD7 in RSS and non-RSS small-for-gestational-age (SGA) patients and identify epigenetic-phenotypic correlations. STUDIED POPULATION AND METHODS: A total of 127 SGA patients were analyzed. Clinical diagnosis of RSS was established when the criterion of being SGA was associated with at least three of five criteria: postnatal growth retardation, relative macrocephaly, prominent forehead, body asymmetry, and feeding difficulties. Serum IGF-II was evaluated for 82 patients. RESULTS: Of the 127 SGA patients, 58 were diagnosed with RSS; 37 of these (63.8%) displayed partial LOM of the 11p15 ICR1 domain, and three (5.2%) had mUPD7. No molecular abnormalities were found in the non-RSS SGA group (n = 69). Birth weight, birth length, and postnatal body mass index (BMI) were lower in the abnormal 11p15 RSS group (ab-ICR1-RSS) than in the normal 11p15 RSS group [-3.4 vs.-2.6 SD score (SDS), -4.4 vs.-3.4 SDS, and -2.5 vs.-1.6 SDS, respectively; P < 0.05]. Among RSS patients, prominent forehead, relative macrocephaly, body asymmetry, and low BMI were significantly associated with ICR1 LOM. All ab-ICR1-RSS patients had at least four of five criteria of the scoring system. Postnatal IGF-II levels were within normal values. CONCLUSION: The 11p15 ICR1 epimutation is a major, specific cause of RSS exhibiting failure to thrive. We propose a clinical scoring system (including a BMI < -2 SDS), highly predictive of 11p15 ICR1 LOM, for the diagnosis of RSS.