Clinical profiles and genetic spectra of 814 Chinese children with short stature

Context Data of and studies based on exome sequencing for the genetic evaluation of short stature are limited, and more large-scale studies are warranted. Some factors increase the likelihood of a monogenic cause of short stature, including skeletal dysplasia, severe short stature, and small for gestational age (SGA) without catch-up growth. However, whether these factors can serve as predictors of molecular diagnosis remains unknown. Objectives We aimed to explore the diagnostic efficiency of the associated risk factors and their exome sequences for screening. Design, Settings, and Patients We defined and applied factors that increased the likelihood of monogenic causes of short stature in diagnostic genetic tests based on next-generation sequencing (NGS) in 814 patients with short stature and at least one other factor. Results Pathogenic/likely pathogenic (P/LP) variants in genes, copy number variations (CNVs), and chromosomal abnormalities were identified in 361 patients. We found P/LP variants among 111 genes, and RASopathies comprised the most important etiology. Short stature combined with other phenotypes significantly increased the likelihood of monogenic cause, including skeletal dysplasia, facial dysmorphism, and intellectual disability, compared with simple severe short stature (<–3 standard deviation scores). We report novel candidate pathogenic genes, KMT2C for unequivocal growth hormone insensitivity and GATA6 for SGA. Conclusions Our study identified the diagnostic characteristics of NGS in short stature with different risk factor. Our study provides novel insights into the current understanding of the etiology of short stature in patients with different phenotypes.

Laron syndrome in three female siblings with the development of subclinical hypothyroidism and dyslipidemia in one case: first report of a Syrian family

ABSTRACT Laron syndrome (LS) is a rare autosomal recessive disorder characterized by dwarfism and typical facial phenotype. This report is the first to present three cases of Laron syndrome affecting three female siblings from Syria. The index case presented at age of 8.5 years with severe short stature: low level of Insulin-like growth factor 1 (IGF-1), elevated levels of fasting and post-stimulation growth hormone (GH), consistent with the diagnosis of Laron syndrome. At the age of 9.5 years, she developed non-autoimmune subclinical hypothyroidism treated with Levothyroxine, then she developed dyslipidemia at the age of 11.3 years. Later, we identified two female siblings of the patient with Laron syndrome. Laron syndrome is a rare genetic disease, reporting of new cases of this rare syndrome must encourage pediatricians to develop high clinical suspicion if faced with patients with very short stature and typical facial features.

Chondrodysplasias With Multiple Dislocations Caused by Defects in Glycosaminoglycan Synthesis

Chondrodysplasias with multiple dislocations form a group of severe disorders characterized by joint laxity and multiple dislocations, severe short stature of pre- and post-natal onset, hand anomalies, and/or vertebral anomalies. The majority of chondrodysplasias with multiple dislocations have been associated with mutations in genes encoding glycosyltransferases, sulfotransferases, and transporters implicated in the synthesis or sulfation of glycosaminoglycans, long and unbranched polysaccharides composed of repeated disaccharide bond to protein core of proteoglycan. Glycosaminoglycan biosynthesis is a tightly regulated process that occurs mainly in the Golgi and that requires the coordinated action of numerous enzymes and transporters as well as an adequate Golgi environment. Any disturbances of this chain of reactions will lead to the incapacity of a cell to construct correct glycanic chains. This review focuses on genetic and glycobiological studies of chondrodysplasias with multiple dislocations associated with glycosaminoglycan biosynthesis defects and related animal models. Strong comprehension of the molecular mechanisms leading to those disorders, mostly through extensive phenotypic analyses of in vitro and/or in vivo models, is essential for the development of novel biomarkers for clinical screenings and innovative therapeutics for these diseases.

Oligogenic Inheritance of Monoallelic TRIP11, FKBP10, NEK1, TBX5, and NBAS Variants Leading to a Phenotype Similar to Odontochondrodysplasia

Skeletal dysplasias are often well characterized, and only a minority of the cases remain unsolved after a thorough analysis of pathogenic variants in over 400 genes that are presently known to cause monogenic skeletal diseases. Here, we describe an 11-year-old Finnish girl, born to unrelated healthy parents, who had severe short stature and a phenotype similar to odontochondrodysplasia (ODCD), a monogenic skeletal dysplasia caused by biallelic TRIP11 variants. The family had previously lost a fetus due to severe skeletal dysplasia. Exome sequencing and bioinformatic analysis revealed an oligogenic inheritance of a heterozygous nonsense mutation in TRIP11 and four likely pathogenic missense variants in FKBP10, TBX5, NEK1, and NBAS in the index patient. Interestingly, all these genes except TBX5 are known to cause skeletal dysplasia in an autosomal recessive manner. In contrast, the fetus was found homozygous for the TRIP11 mutation, and achondrogenesis type IA diagnosis was, thus, molecularly confirmed, indicating two different skeletal dysplasia forms in the family. To the best of our knowledge, this is the first report of an oligogenic inheritance model of a skeletal dysplasia in a Finnish family. Our findings may have implications for genetic counseling and for understanding the yet unsolved cases of rare skeletal dysplasias.

Etiology of severe short stature below −3 SDS in a screened Finnish population

Objective: To describe the etiology of severe short stature in the Helsinki University Hospital district covering a population of 1.2 million that is subject to frequent growth monitoring and screening rules during childhood. Design: Retrospective cohort study. Methods: We identified all subjects born 1990 or later with a height SD score <−3, after the age of 3 years, from the Helsinki University Hospital district growth database. A total of 785 subjects (376 females and 409 males) fulfilled our inclusion criteria; we reviewed their medical records and growth data and report their underlying diagnoses. Results: A pathological cause for short stature was diagnosed in 76% of the girls and 71% of the boys (P = NS). Syndromes were the most numerous pathological cause (n = 160; 20%), followed by organ disorders (n = 127; 16%), growth hormone deficiency (GHD, n = 94; 12%), SGA without catch-up growth (n = 73; 9%), and skeletal dysplasias (n = 57; 7%). Idiopathic short stature (ISS) was diagnosed in 210 (27%) subjects. The probability of growth-related pathology, particularly of a syndrome or skeletal dysplasia, increased with the shorter height SD score and the greater deviation from the target height. Sitting height to height SDS was increased in subjects with ISS, GHD, and SGA (all P < 0.01). Conclusions: Height <−3 SDS after 3 years of age usually results from a pathological cause and should be thoroughly investigated in specialized health care. The chance of finding a specific etiology increased with the severity of short stature, and the mismatch with target height.

Bloom’s syndrome with growth hormone deficiency: a rare association

We report a case of a 5-year-old boy presenting to us with short stature. He was born of consanguineous parentage and was small for gestational age. He had severe short stature, with height Z score of −6.2 SD Score, markedly delayed skeletal age, low level of insulin-like growth factor 1, unstimulated growth hormone and hypoplastic anterior pituitary gland on MRI. He was advised growth hormone (GH) replacement at 2 years of age, but he did not receive it . Later on, he developed photosensitive telangiectatic lesions over face and required multiple hospital admissions for recurrent systemic infections. Genetic analysis confirmed the diagnosis of Bloom’s syndrome. The present case report illustrates the need for high vigilance for conditions like Bloom’s syndrome in growth hormone deficiency (GHD), in whom GH treatment could potentially be harmful. Bloom’s syndrome with GHD is an exceedingly rare association.

Mutations of uncertain significance in heterozygous variants as a possible cause of severe short stature: a case report

Background Linear bone growth is achieved by the division of chondrocytes at the growth plate and is regulated by endocrine and paracrine factors such as growth hormone. Mutations that negatively affect chondrogenesis can be a contributor to short stature. One such mutation can occur in the ACAN gene, causing short stature and advanced bone age. Similarly, mutations in growth hormone receptors (GHR) can lead to Laron syndrome (LS), one of the several disorders that are collectively called growth hormone insensitivity syndrome (GHI). Another example is Floating-Harbor syndrome (FHS), a rare autosomal dominant due to mutations in the SRCAP gene that can also result in short stature. Case presentation We report the case of a 6-year-old female with concomitant mutations in the three genes mentioned above. The mutations reported here were found on genetic studies and are usually benign, causing a variant of undetermined significance. However, our patient’s phenotype could only be explained by the compounded effects of pathogenic mutations of these genes. Some of the same mutations were also found in the patient’s father and her paternal grandfather. Both also presented with short stature, though not to the same degree as our patient. While these mutations are often reported to be insignificant, they gave rise to severe short stature and a specific phenotype in the patient when presented together. We think that even though the GHI spectrum is inherited through an autosomal recessive pattern, the sum of these heterozygous mutations resulted in severe short stature despite the limited GHI seen in our patient, the father, and the grandfather, through a rare ACAN and SRCAP mutation that, to our knowledge, has not been previously reported as a pathogenic mutation in the literature. Conclusion We investigated the possible synergistic effects of these variations on exacerbation or masking of the signs and symptoms of GHI with the hope of providing a better understanding of these genes and their function through our rare case.

The phosphatase inhibitor LB-100 acts synergistically with the NPR2 agonist BMN-111 to improve bone growth

ABSTRACTActivating mutations in fibroblast growth factor receptor 3 (FGFR3) and inactivating mutations in the natriuretic peptide receptor 2 (NPR2) guanylyl cyclase both result in decreased production of cyclic GMP (cGMP) in chondrocytes and severe short stature, causing achondroplasia (ACH) and acrosomelic dysplasia type Maroteaux, respectively. Previously we showed that an NPR2 agonist BMN-111 (vosoritide) increases bone growth in mice mimicking ACH (Fgfr3Y367C/+), and that in control growth plate chondrocytes, FGFR3 signaling decreases NPR2 activity by dephosphorylating the NPR2 protein. Here we tested whether a phosphatase inhibitor (LB-100) could enhance bone growth in ACH. In ex vivo imaging experiments using a FRET sensor to measure cGMP production in chondrocytes of living tibias from newborn mice, LB-100 counteracts the FGF-induced dephosphorylation and inactivation of NPR2. In ex vivo experiments with Fgfr3Y367C/+ mice, LB-100 in combination with BMN-111 increases the rate of femur growth by ∼25% vs BMN-111 alone, restores chondrocyte terminal differentiation, increases the proliferative growth plate area of the femur, and reduces the activity of the MAP kinase pathway. Our results provide a proof of concept that a phosphatase inhibitor could be used together with an NPR2 agonist to enhance cGMP production as a therapy for ACH.GRAPHICAL ABSTRACT