[Research progress on the pathogenic mechanisms, diagnosis and treatment of McCune-Albright syndrome].

McCune-Albright syndrome is a rare chimeric disorder due to mutations in the postzygotic GNAS gene. It belongs to the group of guanine nucleotide-binding protein diseases, affecting a wide range of individuals. It is characterized by fibrous dysplasia, café-au-lait skin macules, and precocious puberty with other variable clinical manifestations. At present, there are difficulties in the molecular diagnosis of McCune-Albright syndrome, and there is a lack of effective clinical treatments to halt or reverse the course and regression of the disease. This article summarizes the clinical manifestations, diagnosis, pathogenic molecular mechanisms, treatment and relevant fertility guidelines of McCune-Albright syndrome, with a view to further research and therapy of McCune-Albright syndrome.

Novel variants in TNRC6B cause global developmental delay with speech and behavioral abnormalities, short stature, low body weight, café-au-lait spots, and metabolic abnormality.

BACKGROUND: TNRC6B deficiency syndrome, also known as global developmental delay with speech and behavioral abnormalities (MIM 619243), is a rare autosomal dominant genetic disease mainly characterized by facial dysmorphism, developmental delay/intellectual disability (DD/ID), speech and language delay, fine and motor delay, attention deficit and hyperactivity disorder (ADHD), and variable behavioral abnormalities. It is caused by heterozygous variant in the TNRC6B gene (NM_001162501.2, MIM 610740), which encodes the trinucleotide repeat-containing adaptor 6B protein. METHODS: In this study, two Chinese patients with TNRC6B deficiency syndrome were recruited, and genomic DNA extraction from peripheral blood leukocytes of these parents and their family members was extracted for whole-exome sequencing and Sanger sequencing. RESULTS: Here, we report two unrelated Chinese patients diagnosed with TNRC6B deficiency syndrome caused by novel de novo likely pathogenic or pathogenic TNRC6B variants c.335C>T (p.Pro112Leu) and c.1632delC (p.Leu546fs*63), which expands the genetic spectrum of TNRC6B deficiency syndrome. The clinical features of the patients were DD/ID, delayed speech, ADHD, behavioral abnormalities, short stature, low body weight, café-au-lait spots, metabolic abnormalities, and facial dysmorphism including coarse facial features, sparse hair, frontal bossing, hypertelorism, amblyopia, strabismus, and downslanted palpebral fissures, which expands the phenotype spectrum associated with TNRC6B deficiency syndrome. CONCLUSION: This study expands the genotypic and phenotypic spectrum of TNRC6B deficiency syndrome. Our findings indicate that patients with TNRC6B deficiency syndrome should be monitored for growth and metabolic problems and therapeutic strategies should be developed to address these problems. Our report also suggests the clinical diversity of TNRC6B deficiency syndrome.

Genetically confirmed coexistence of neurofibromatosis type 1 and Cherubism in a pediatric patient.

BACKGROUND: Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder typified by various combination of numerous Café-au-lait macules, cutaneous and plexiform neurofibromas, freckling of inguinal or axillary region, optic glioma, Lisch nodules and osseous lesions. Cherubism is a rare genetic syndrome described by progressive swelling of the lower and/or upper jaw due to replacement of bone by fibrous connective tissue. Patients are reported in the literature with NF1 and cherubism-like phenotype due to the NF1 osseous lesions in the jaws. The purpose of this case report is the description of a young male genetically diagnosed with both NF1 and cherubism. METHODS AND RESULTS: A 9 years and six month old patient with clinical findings of NF1 and cherubism in whom both diseases were genetically confirmed, is presented. The patient was evaluated by a pediatrician, a pediatric endocrinologist, an ophthalmologist, and an oral and maxillofacial surgeon. A laboratory and hormonal screening, a histological examination, a chest X-ray, a magnetic resonance imaging (MRI) of the orbit and a digital panoramic radiography were performed. Genetic testing applying Whole Exome Sequencing was conducted. CONCLUSIONS: A novel and an already reported pathogenic variants were detected in NF1 and SH3BP2 genes, respectively. This is the first described patient with coexistence of NF1 and cherubism. The contribution of Next Generation Sequencing (NGS) in gene variant identification as well as the importance of close collaboration between laboratory scientists and clinicians, is highlighted. Both are essential for optimizing the diagnostic approach of patients with a complex phenotype.

Epilepsy in Legius syndrome: Coincidence or causation?

Legius syndrome is a rare genetic disorder, caused by heterozygous SPRED1 pathogenic variants, which shares phenotypic features with neurofibromatosis type 1 (NF1). Both conditions typically involve café-au-lait macules, axillary freckling, and macrocephaly; however, patients with NF1 are also at risk for tumors, such as optic nerve gliomas and neurofibromas. Seizure risk is known to be elevated in NF1, but there has been little study of this aspect of Legius syndrome. The reported epilepsy incidence is 3.3%-5%, well above the general population incidence of ~0.5%-1%, but the few reports in the literature have very little data regarding epilepsy phenotype. We identified two unrelated individuals, both with Legius syndrome and epilepsy, and performed thorough phenotyping. One individual's mother also had Legius syndrome and now-resolved childhood epilepsy, as well as reports of more distant relatives who also had multiple café-au-lait macules and seizures. Both probands had experienced childhood-onset focal seizures, with normal brain MRI. In one patient, EEG later showed apparently generalized epileptiform abnormalities. Based on the data from this small case series and literature review, seizure risk is increased in people with Legius syndrome, but the epilepsy prognosis appears to be generally good, with patients having either self-limited or pharmacoresponsive courses.

[Analysis of clinical features and variants of NF1 gene in 12 patients with Neurofibromatosis type 1].

OBJECTIVE: To explore the types of NF1 gene variants and clinical characteristics among patients with Neurofibromatosis type I (NF1). METHODS: Clinical data of 12 patients diagnosed at Ningbo Women and Children's Hospital between December 2019 and May 2022 were retrospectively analyzed. The probands and their family members were subjected to high-throughput sequencing, and candidate variants were verified by Sanger sequencing and chromosome microarray analysis. RESULTS: The 12 patients had ranged from 4 months to 27 years old, with a male-to-female ratio of 2 : 1. Cafè-au-lait spots were found in all patients. 83.3% of them also had axillary and/or inguinal freckling, 58.3% had neurofibromas, and 16.7% had congenital pseudarthrosis of the tibia. Five types of NF1 gene variants were identified in the patients, including 5 nonsense variants, 4 frameshift variants, 1 missense variant, 1 splice variant, 1 large deletion involving the whole gene. Six patients were found to harbor de novo variants, 2 had inherited the variants from their parents, and 4 were not verified for their parental origin. The c.3379del (p.Thr1127Glnfs*15) and c.6628_6629del (p.Glu2210Thrfs*10) variants were unreported in literature and databases. CONCLUSION: Most NF1 patients may present with Cafè-au-lait spots initially and are due to pathogenic variant of the NF1 gene. High-throughput sequencing can efficiently identify such variants among the patients and enable the definite diagnosis.

[MULTIPLE CAFÉ-AU-LAIT MACULES AND INTERTRIGINOUS FRECKLING: BEYOND THE RASOPATHIES].

INTRODUCTION: Piebaldism is the dominantly inherited skin disorder clinically characterized by congenital stable and well circumscribed patches of leukoderma (depigmented skin) of ventral distribution, involving central forehead, frontal chest and abdomen and central portion of limbs, and by localized poliosis (white hair). Inherited or de novo mutations in proto-oncogene KIT, encoding the transmembrane tyrosine kinase receptor c-kit, underly the majority of piebaldism cases. Piebaldism is a disorder characterized by incomplete penetrance and variable expressivity.

Genetic evaluation of 50 Turkish patients with neurofibromatosis type 1: 2 years experience of a single center.

BACKGROUND/AIM: Neurofibromatosis type 1 is an autosomal dominant neurocutaneous disorder. Clinical diagnosis is difficult in early childhood, and it is possible to miss a critical interval for tumour screening. In this study, we aimed to characterize the mutational spectrum of Turkish patients and discuss the benefits of molecular testing. MATERIAL AND METHODS: Fifty individuals from 35 unrelated families were included. Main referral reasons for genetic testing were as follows: to confirm a clinical diagnosis, to use in differential diagnosis and to evaluate first-degree family member of a known patient. Two-step process consisting of initial next generation sequencing of the NF1 gene and consequent multiplex ligation-dependent probe amplification were performed. RESULTS: We identified a total of 30 variants in 28 individuals. Variant detection rate was 56% in the entire study group and 71.4% within the index patients. Four novel variants were found. Truncating variants constituted 60% of the entire mutation spectrum. A deletion or duplication was not detected. The most common feature was cafe au lait macules in 70% of the patients, followed by focal areas of signal intensity on brain imaging (26%), cutaneous neurofibromas (24%) and axillary freckling (24%). CONCLUSIONS: Early sequencing in all suspected patients followed by deletion/duplication analysis in patients meeting clinical criteria and a case-to-case based consideration for RNA studies seems to be the effective algorithm for NF-1 diagnosis.

Characteristics of Café-au-lait Macules and their Association with the Neurofibromatosis type I Genotype in a Cohort of Greek Children.

Cafe-au-lait macules are the most distinctive clinical finding in neurofibromatosis type I. The aim of this prospective study of Greek children diagnosed with neurofibromatosis type I was to describe the dermatological phenotype and to analyse the characteristics of cafe-au-lait macules and their association with genotype. Pigment intensity and melatonin content of cafe-au-lait macules were measured with a narrowband spectrophotometer. A total of 63 children aged 6 months to 16 years old were studied. Mean melanin content varied, both among patients, and within each patient (p < 0.001). Females had a higher number of cafe-au-lait macules than did males (p = 0.025), and the melanin content of cafe-au-lait macules was lower in females than males (p < 0.001). Patients with protein-truncating variants in the neurofibromatosis type I gene had higher melanin content of cafe-au-lait macules than other types of genetic variants t (55) = 2.196, p = 0.032. Plexiform neurofibromas were also detected in the majority of patients with protein- truncating variants, while juvenile xanthogranulomas were detected equally in patients with protein-truncating and non-protein-truncating variants. In conclusion, cafe-au-lait macules with high melatonin content are associated with patients carrying non-protein-truncating variants. Therefore, measurement of cafe-au-lait macule pigment intensity might provide useful information for initial assessment of patients with neurofibromatosis type I and the severity of their future phenotype.

Piebaldism with café-au-lait macules resulting from a novel mutation of KIT gene in a three-generation Chinese family.

BACKGROUND: Piebaldism is a rare, autosomal dominant, and congenital pigmentary disorder characterized by stable depigmentation of the skin and white forelock. Mutations in KIT or SLUG genes result in piebaldism. Most individuals with piebaldism have a family history of the disorder. METHODS: In this paper, we report a case of piebaldism with café-au-lait macules resulting from a novel mutation of KIT gene c.1982C > T (p.Thr661Ile) in a three-generation Chinese family. The whole-exome sequencing, mitochondrial gene 3000X, and bioinformatics tools were used to identify the mutation in this new-found pedigree. In addition, we searched the databases of "Punmed, Chinese National Knowledge Infrastructure, CMJD, WANFANG MED ONLINE", reviewed 88 cases of piebaldism caused by KIT gene mutation, and summarized the relationship between clinical phenotype and genotype of piebaldism through logistic regression and other statistical methods. RESULTS: The proband and her affected mother carried a heterozygous c.1982C > T missense mutation (p.Thr661Ile) on KIT gene. Bioinformatics analysis hinted that it had potential pathogenicity. The data showed that piebaldism patients with cafè-au-lait macules had KIT mutations almost located in the intracellular tyrosine kinase domain and were mostly related to the severe clinical phenotype of piebaldism. CONCLUSION: The new heterozygous c.1982C > T missense mutation on KIT caused piebaldism with café-au-lait macules in this Chinese family. This study provides a new reference index for clinicians to judge the severity of clinical phenotypes of piebaldism, broadens the understanding of the correlation between clinical phenotypes and genotypes of piebaldism, and provides reference of genetic counseling and prenatal diagnosis for affected families.

McCune-Albright Syndrome: A Case Report and Review of Literature.

McCune-Albright syndrome (MAS) is a rare sporadic condition defined by the classic triad of fibrous dysplasia of bone, café au lait skin macules, and hyperfunctioning endocrinopathies. The molecular basis of MAS has been ascribed to the post-zygotic somatic gain-of-function mutations in the GNAS gene, which encodes the alpha subunit of G proteins, leading to constitutive activation of several G Protein-Coupled Receptors (GPCRs). The co-occurrence of two of the above-mentioned cardinal clinical manifestations sets the diagnosis at the clinical level. In this case report, we describe a 27-month-old girl who presented with gonadotropin-independent precocious puberty secondary to an estrogen-secreting ovarian cyst, a café au lait skin macule and growth hormone, and prolactin excess, and we provide an updated review of the scientific literature on the clinical features, diagnostic work-up, and therapeutic management of MAS.

Novel, heterozygous, de novo pathogenic variant (c.4963delA: p.Thr1656Glnfs*42) of the NF1 gene in a Chinese family with neurofibromatosis type 1.

Neurofibromatosis type 1 (NF1) presents an autosomal dominant, haploinsufficient, and multisystemic disorder with patches of skin café-au-lait spots, lisch nodules in the iris, even tumors in the peripheral nervous system or fibromatous skin. In this study, a Chinese young woman who suffered from NF1 disease with first-trimester spontaneous abortion was recruited. Analysis for whole exome sequencing (WES), Sanger sequencing, short tandem repeat (STR), and co-segregation was carried out. As results, a novel, heterozygous, de novo pathogenic variant (c.4963delA:p.Thr1656Glnfs*42) of the NF1 gene in the proband was identified. This pathogenic variant of the NF1 gene produced a truncated protein that lost more than one-third of the NF1 protein at the C-terminus including half of the CRAL-TRIO lipid-binding domain and nuclear localization signal (NLS), thus leading to pathogenicity (ACMG criteria: PVS1 + PM2 + PM2). Analysis for NF1 conservation in species revealed high conservation in different species. Analysis of NF1 mRNA levels in different human tissues showed low tissue specificity, which may affect multiple organs presenting other symptoms or phenotypes. Moreover, prenatal NF1 gene diagnosis showed both alleles as wild types. Thus, this NF1 novel variant probably underlays the NF1 pathogenesis in this pedigree, which would help for the diagnosis, genetic counseling, and clinical management of this disorder.

Constitutional Mismatch Repair Deficiency Syndromes, a Neurofibromatosis 1 Mimicker That Hinders Timely Management.

BACKGROUND: Constitutional mismatch repair deficiency (CMMRD) is a rare, autosomal recessive disease caused by a biallelic germline mutation in one of the DNA mismatch repair genes ( MLH1 , MSH2 , MSH6 and PMS2 ). In addition to colorectal, brain, and hematological malignancies, many additional premalignant and non-malignant features that can point toward the diagnosis of CMMRD have been reported. The report from the CMMRD consortium revealed that all children with CMMRD have café-au-lait macules (CALMs) but the number of CALMs does not reach > 5 in all CMMRD patients, which is one of the diagnostic criterions of NF1. About half of the patients with CMMRD develop brain tumors and up to 40% develop metachronous second malignancies. METHODS: This is an observational retrospective case series describing five pediatric patients with CMMRD. RESULTS: All the five patients in our cohort developed brain tumors and showed a predilection to the frontal lobe. In our cohort, multiple Mongolian spots, coloboma, obesity, CHD, dysmorphism, and clubfoot were also encountered. In all our patients, NF1 and other tumorigenic predisposing syndromes were initially suspected. CONCLUSION: Increasing awareness of this condition and its shared reminiscent NF1 features, particularly CALMs among child neurologists, oncologists, geneticists, and dermatologists can help uncover the tip of the iceberg of CMMRD that carries an important consequence on management.

Low rates of neurological abnormalities in patients with pigmentary mosaicism: A retrospective cohort study from a tertiary dermatology center.

BACKGROUND: Pigmentary mosaicism (PM) is a descriptive term encompassing a range of hyper- and hypo-pigmented phenotypes in various patterns. Information from the neurology literature initially noted neurological abnormalities (NA) in up to 90% of children with PM. The dermatology literature suggests lower associated rates (15%-30%) of NA. Variations in terminology, inclusion criteria, and small population sizes makes interpreting existing PM literature complicated. We aimed to assess rates of NA in children presenting to dermatology with PM. METHODS: We included patients <19 years, diagnosed with PM, nevus depigmentosus and/or segmental café au lait macules (CALM) seen in our dermatology department between 1 January 2006 and 31 December 2020. Patients with neurofibromatosis, McCune-Albright syndrome, and non-segmental CALM were excluded. Data collected included pigmentation, pattern, site(s) affected, presence of seizures, developmental delay, and microcephaly. RESULTS: One hundred fifty patients were included (49.3% female), with a mean age at diagnosis of 4.27 years. Patterns of mosaicism were ascertained for 149 patients and included blaschkolinear (60/149, 40.3%), blocklike (79/149, 53.0%), or a combination of both patterns (10/149, 6.7%). Patients with a combination of patterns were more likely to have NA (p < .01). Overall, 22/149 (14.8%) had NA. Nine out of twenty-two patients with NA had hypopigmented blaschkolinear lesions (40.9%). Patients with ≥4 body sites affected were more likely to have NA (p < .01). DISCUSSION: Overall, our population had low rates of NA in PM patients. A combination of blaschkolinear and blocklike patterns, or ≥4 body sites involved were associated with higher rates of NA.

Rhabdomyosarcoma as the first presentation in Neurofibromatosis Type 1: case series and review of the literature.

Neurofibromatosis Type 1 (NF1) is a neurocutaneous syndrome characterized by multiple café-au-lait macules, neurofibromas, and predisposition to malignancies, including rhabdomyosarcomas (RMS). Somatic NF1 mutations occur in RMS and other cancers, and ∼1% of patients with RMS have NF1. We describe three patients who presented prior to one year of age with RMS and were subsequently diagnosed with NF1. Compared to sporadic RMS, patients with this cancer predisposition syndrome are diagnosed younger, genitourinary sites are more common, and tumors are almost exclusively the embryonal subtype. Genomic sequencing of the tumor was initiated in one patient, and we identified a second sequence variant in NF1. The identification of molecular drivers in tumors is changing the nature of pediatric oncology by informing therapeutics targeted to specific molecular pathways and selecting patients who are likely to harbor germline variants in cancer predisposition genes who would benefit from a Medical Genetics assessment.

Novel, heterozygous, pathogenic variant (c.4272delA: p.I1426Ffs*2) for the NF1 gene in a large Chinese family with neurofibromatosis type 1.

BACKGROUND: Neurofibromatosis type 1 (NF1) is an autosomal dominant with haploinsufficient, and multisystemic disorder including patches of skin Café-au-lait spots, Lisch nodules in the iris, and tumors in the peripheral nervous systems or fibromatous skin. METHODS: Blood samples were collected and DNA was extracted from a large Chinese pedigree suffering from NF1 disease with three spontaneous abortions or death for proband. Analysis for whole exome sequencing (WES), Sanger sequencing, and co-segregation was carried out. Prenatal gene diagnosis was also carried out in amniotic fluid DNA. The expression of NF1 was conducted by bioinformatics. RESULTS: A large Chinese pedigree with NF1 was recruited and a novel, heterozygous, variant (c.4272delA: p.I1426Ffs*2) for the NF1 gene in the proband was identified. This variant of NF1 produced a truncated protein that losses half of NF1 protein at the C-terminus including the CRAL-TRIO lipid-binding domain, NLS, and a small portion of Ras-GAP domain, thus leading to pathogenicity (ACMG criteria: PVS1 + PM2). NF1 expressions in different human tissues showed low tissue specificity, which may affect multiple organs presenting different phenotypes. Moreover, prenatal gene diagnosis for NF1 showed both alleles as wild types in the fetus of the proband. CONCLUSION: We thus successfully identified a novel, pathogenic, heterozygous variant (c.4272delA:p.I1426Ffs*2) in the NF1 gene of NF1 disorder, expanding the NF1 mutation spectrum, that will help elucidate the molecular pathogenesis of NF1 disease and to contribute to the NF1 diagnosis, genetic counseling, clinical management in this large Chinese family.

[Genetic diagnosis of a child with Café-au-lait macules and juvenile xanthogranuloma].

OBJECTIVE: To explore the genetic basis for a child with café-au-lait macules and juvenile xanthogranuloma. METHODS: Clinical data and peripheral blood samples of the patient and her family members were collected and subjected to targeted capture and high-throughput sequencing. Candidate variant was verified by Sanger sequencing. RESULTS: A deletional variant in exon 23 of the NF1 gene was detected in the proband. Sanger sequencing has verified it as a de novo variant, which was highly correlated with the clinical manifestations of the patient and her mother. The diagnosis of neurofibromatosis 1 (NF1) was established. The variant was unreported previously. CONCLUSION: Targeted capture and next-generation sequencing combined with Sanger sequencing can facilitate early diagnosis of NF1 and provide a basis for the clinical treatment, genetic counseling and prenatal diagnosis.

A novel NF1 mutation in a pediatric patient with renal artery aneurysm.

BACKGROUND: Neurofibromatosis type 1 (NF1) is a neurocutaneous syndrome, due to heterozygous pathogenic variants in NF1 gene. The main clinical manifestations are multiple café au lait spots, axillary and inguinal freckling, cutaneous and plexiform neurofibromas, optic glioma, Lisch nodules and osseous lesions, such as sphenoid and tibial dysplasia. Vasculopathy is another feature of NF1; it consists of stenosis, aneurysms, and arteriovenous malformations, frequently involving renal arteries. CASE PRESENTATION: We report on a 9-year-old girl with a novel mutation in NF1 gene and renal artery aneurysm, treated by coil embolization and complicated with hypertension. CONCLUSION: Vasculopathy is a complication of NF1, affecting from 0.4 to 6.4% of patients with NF1. Among the vascular abnormalities, renal artery aneurysm is a rare manifestation, with only a few cases regarding adult patients and no pediatric reports described in current literature. The finding of a vascular abnormality in a specific site requires the evaluation of the entire vascular system because multiple vessels could be involved at the same time.

Protocolo de diagnóstico y seguimiento de pacientes adultos con neurofibromatosis tipo 1 en una unidad de referencia española / Diagnostic and follow-up protocol for adult patients with neurofibromatosis type 1 in a Spanish reference unit

La neurofibromatosis tipo 1 es uno de los trastornos genéticos neurocutáneos más frecuentes. La característica de esta enfermedad es la afectación cutánea en forma de manchas «café con leche», efélides y los característicos neurofibromas cutáneos. Otras manifestaciones frecuentes incluyen las alteraciones óseas, la «vasculopatía por neurofibromatosis tipo 1» y los problemas neurocognitivos. Además, los pacientes tienen más riesgo de padecer una gran variedad de neoplasias malignas, incluida la transformación maligna de neurofibromas plexiformes. Para ser capaces de brindar una atención óptima a estos pacientes, que presentan una afectación multisistémica y potencialmente grave, es necesario conocer las diversas características clínicas de este trastorno, así como propiciar un seguimiento y abordaje terapéutico precoz y multidisciplinar. En esta revisión, resumimos el diagnóstico, las principales características clínicas y proponemos un protocolo de cribado y seguimiento de pacientes adultos con neurofibromatosis tipo 1 (AU)

Neurofibromatosis type 1 is one of the most common genetic neurocutaneous disorders. The hallmark of this disease is skin lesions in the form of café-au-lait spots, ephelides, and the characteristic cutaneous neurofibromas. Other common manifestations include bone abnormalities, «neurofibromatosis type 1 vasculopathy», and neurocognitive disorders. In addition, patients are at an increased risk for a wide variety of malignant neoplasms, including the malignant transformation of plexiform neurofibromas. It is necessary to know the various clinical characteristics of this disorder and to provide an early, multidisciplinary follow-up and treatment approach in order to provide optimal care to these patients, who present with a multisystemic disease that is potentially severe. This review summarizes the diagnosis and main clinical characteristics and suggests a protocol for screening and follow-up of adult patients with neurofibromatosis type 1 (AU)

Caracterización clínica de pacientes chilenos con displasia fibrosa/síndrome de McCune-Albright / Clinical features of Chilean patients with Fibrous Dysplasia/McCune-Albright Syndrome

BACKGROUND: Fibrous Dysplasia/McCune-Albright Syndrome (FD/MAS) is characterized by a spectrum of manifestations that may include fibrous dysplasia of bone and multiple endocrinopathies. AIM: To describe the clinical spectrum, the study and follow-up of patients with FD/MAS cared at our institution. MATERIAL AND METHODS: Review of medical records of 12 pediatric and adult patients (11 women) who met the clinical and genetic diagnostic criteria for FD/ MAS. RESULTS: The patients' mean age at diagnosis was 4.9 ± 5.5 years. The most common initial clinical manifestation was peripheral precocious puberty (PPP) in 67% of patients and 75% had café-au-lait spots. Fibrous dysplasia was present in 75% of patients and the mean age at diagnosis was 7.9 ± 4.7 years. Ten patients had a bone scintigraphy, with an age at the first examination that varied between 2 and 38 years of age. The most frequent location of dysplasia was craniofacial and appendicular. No patient had a recorded history of cholestasis, hepatitis, or pancreatitis. In four patients, a genetic study was performed that was positive for the pathogenic variant of guanine nucleotide binding protein, alpha stimulating (GNAS). CONCLUSIONS: These patients demonstrate the variable nature of the clinical presentation and study of FD/MAS. It is essential to increase the index of diagnostic suspicion and adherence to international recommendations.