A Rare Cause of Short Stature: 3M Syndrome in a Patient with Novel Mutation in OBSL1 Gene

Large scale sequence-based screen for recessive variants allows for identification and monitoring of rare deleterious variants in pigs

Most deleterious variants are recessive and segregate at relatively low frequency. Therefore, high sample sizes are required to identify these variants. In this study we report a large-scale sequence based genome-wide association study (GWAS) in pigs, with a total of 120,000 Large White and 80,000 Synthetic breed animals imputed to sequence using a reference population of approximately 1,100 whole genome sequenced pigs. We imputed over 20 million variants with high accuracies (R2>0.9) even for low frequency variants (1-5% minor allele frequency). This sequence-based analysis revealed a total of 14 additive and 9 non-additive significant quantitative trait loci (QTLs) for growth rate and backfat thickness. With the non-additive (recessive) model, we identified a deleterious missense SNP in the CDHR2 gene reducing growth rate and backfat in homozygous Large White animals. For the Synthetic breed, we revealed a QTL on chromosome 15 with a frameshift variant in the OBSL1 gene. This QTL has a major impact on both growth rate and backfat, resembling human 3M-syndrome 2 which is related to the same gene. With the additive model, we confirmed known QTLs on chromosomes 1 and 5 for both breeds, including variants in the MC4R and CCND2 genes. On chromosome 1, we disentangled a complex QTL region with multiple variants affecting both traits, harboring 4 independent QTLs in the span of 5 Mb. Together we present a large scale sequence-based association study that provides a key resource to scan for novel variants at high resolution for breeding and to further reduce the frequency of deleterious alleles at an early stage in the breeding program.

3M syndrome: Evaluating the clinical and laboratory features and the response of the growth hormone treatment: Single center experience

INTRODUCTION & OBJECTIVE

3 M Syndrome is a rarely encountered autosomal recessive syndrome characterized by low birth weight, severe postnatal growth deficiency, and minor dysmorphic abnormalities. 3 M-related short stature has been attributed to the resistance to growth hormone (GH) to a certain extent rather than to GH deficiency. The resistance to GH, on the other hand, has been associated with impaired protein scaffolding, transport, and p53-mediated apoptosis at the IGF-1 post-receptor pathway. In this context, the objective of this study is to evaluate the clinical, laboratory, and genetic characteristics of the patients with 3 M syndrome, detect the mutations frequently observed in these patients, and assess their response to GH treatment.

MATERIAL&METHODS

The sample of this single-center study consisted of patients diagnosed with 3 M syndrome based on genetic tests between 2007 and 2021. Patients' clinic, laboratory, and genetic characteristics pertaining to the time of admission and follow-up were recorded. All patients except one underwent a growth hormone stimulation test (GHST) (Levo-dopa or insulin tolerance test). Insulin-like growth factor (IGF) generation test was performed on those with sufficient GHST results (0.1 mg/kg/day for four days).

RESULTS

The median age of the patients, five females and three males, was 2.8 (0.25-8.12) years at admission. All but one patient were small for gestational age (SGA). The patient with normal birth weight was the baby of a diabetic mother. Obscurin-like 1 (OBSL1) variant was detected in all cases. The median height standard deviation score (SDS) at admission was -4.94 ((-5.63)- (-3.27)) SDS, and the median midparenteral height SDS was -1.27 SDS ((-3.1)- (0.34)). All patients were prepubertal at admission. The GHST response was sufficient in five cases. IGF generation test was performed in three cases. Seven patients received GH therapy (35-57 μg/kg/day). Five of these patients discontinued GH therapy since their growth velocity (GV) fell below normal during treatment. In addition, one case discontinued GH therapy because her IGF-1 value was>2 SDS, and another case received gonadotropin-releasing hormone (GnRH) analogs together with GH therapy. The median age and height SDS of the patients were 10.1 (1.79-18) years and -5.09 SDS ((-7.11)- (2.45)), respectively, as of the last follow-up visit. The height SDS values of the two cases that reached the final height were -7.11 SDS and -3.39 SDS. There were no side effects of GH treatment.

CONCLUSION

The study findings indicated a good GV during the early stages of the long-term GH treatment administered to patients with 3 M syndrome. However, response to GH therapy decreased in the following years, and the desired improvement in height SDS could not be achieved in patients who reached their final heights. Taken together with the literature data, it has been concluded that initiating GH therapy in the prepubertal period provided better outcomes than after puberty.

Expanding OBSL1 Mutation Phenotype: Disproportionate Short Stature, Barrel Chest, Thoracic Kyphoscoliosis, Hypogonadism, and Hypospadias

We present a Pakistani kinship afflicted with a syndrome with features including short stature, reduced sitting height, orofacial symptoms including prominent forehead and thick eyebrows, short and broad thorax, and variable features such as long philtrum, short broad neck, barrel chest, thoracic kyphoscoliosis, hypogonadism, and hypospadias. Phenotypic variation even within different sibships was considerable. The unique combination of the phenotypic characteristics prompted us to determine the shared homozygosity regions in patient genomes and the pathogenic variants by next generation technologies like single nucleotide polymorphism (SNP) genotyping and whole exome sequencing (WES). Through these analyses, we detected homozygous OBSL1 c.848delG (p.Gly283AlafsTer54) as the causal variant. Biallelic variants in OBSL1 are known to cause Three M Syndrome 2 (3M2), a rare disorder of growth retardation with characteristic facial dysmorphism and musculoskeletal abnormalities. Affected members of the family do not have the 3M2 hallmark features of dolichocephaly, hypoplastic midface, anteverted nares, low nasal bridge, pectus excavatum, sacral hyperlordosis, spina bifida occulta, anterior wedging of thoracic vertebrae, prominent heels, and prominent talus. Moreover, they have some variable features not typical for the syndrome such as round face, disproportionate short stature, barrel chest, thoracic kyphoscoliosis, hypogonadism, and hypospadias. Our study facilitated genetic diagnosis in the family, expanded the clinical phenotype for 3M2, and unraveled the considerable clinical variation within the same kinship. We conclude that unbiased molecular analyses such as WES should be more integrated into healthcare, particularly in populations with high parental consanguinity, given the potential of such analyses to facilitate diagnosis.

3-M syndrome - a primordial short stature disorder with novel CUL7 mutation in two Indian patients

OBJECTIVE

To evaluate the cause of short stature in children.

CASE PRESENTATION

Two children with suspected skeletal dysplasia and short stature were evaluated.

CONCLUSIONS

The 3-M syndrome is a primordial growth disorder manifesting severe postnatal growth restriction, skeletal anomalies and prominent fleshy heels. The 3-M syndrome is a genetically heterogeneous disorder and the phenotype is similar. This is a rare autosomal recessive disorder with normal intellect. Two affected children have been identified by whole-exome sequencing. One patient harboured a compound heterozygous variant and the other was a homozygous missense variant. The genetic diagnosis helped in counselling the families and facilitated prenatal diagnosis in one (case 1) family.

A rare cause of syndromic short stature: 3M syndrome in three families

3M syndrome is a rare autosomal recessive genetic disorder characterized by severe growth retardation, dysmorphic facial features, skeletal dysplasia, and normal intelligence. Variants in CUL7, OBSL1, and CCDC8 genes have been reported to be responsible for this syndrome. In this study, the clinical and molecular findings of four 3M syndrome cases from three families are presented. All cases had growth retardation, relative macrocephaly, and typical dysmorphic facial features. Their neurological developments were normal. Sequencing of CUL7, OBSL1, and CCDC8 genes revealed two different novel homozygous variants in CUL7 in Families 1 and 3 and a previously reported homozygous pathogenic variant in OBSL1 in Family 2. In conclusion, a comprehensive dysmorphological evaluation should be obtained in individuals presenting with short stature and in such individuals with typical facial and skeletal findings, 3M syndrome should be considered. Our report expands the genotype of 3M syndrome and emphasizes the importance of thorough physical and dysmorphological examination.

The Effect of Combined Growth Hormone and a Gonadotropin-Releasing Hormone Agonist Therapy on Height in Korean 3-M Syndrome Siblings

3-M syndrome is a rare autosomal recessive growth disorder characterized by severe growth retardation, low birth weight, characteristic facial features, and skeletal anomalies, for which three causative genes (CUL7, OBSL1, and CCDC8) have been identified. We herein report two Korean siblings with 3-M syndrome caused by two novel OBSL1 mutations, and describe the effect of a combined treatment with growth hormone (GH) and a gonadotropin-releasing hormone (GnRH) agonist. A 7-year-old girl with short stature (-3.37 standard deviation score, SDS) and breast budding presented with subtle dysmorphic features, including macrocephaly, frontal bossing, a triangular face, prominent philtrum, full lips, a short neck, and fifth-finger clinodactyly. GnRH stimulation test revealed a pubertal pattern and advanced bone age of 8 years and 10 months. Her older sister, aged 10 years and 9 months, had experienced an early menarche, and had an advanced bone age (13.5 years) and predicted adult height of 142 cm (-4.04 SDS). Targeted exome sequencing identified that the siblings had two heteroallelic mutations in OBSL1. Both siblings underwent a combination therapy with GH and a GnRH agonist. A height gain was noted in both siblings even after short-term treatment. To fully elucidate the effects of the combined therapy, a larger cohort should be analyzed following a longer treatment period. However, such an analysis would be challenging due to the rarity of this disease.

Identification of two CUL7 variants in two Chinese families with 3-M syndrome by whole-exome sequencing

Background

3‐M syndrome is a rare autosomal recessive disorder characterized by primordial growth retardation, large head circumference, characteristic facial features, and mild skeletal changes, which is associated with the exclusive variants in three genes, namely CUL7, OBSL1, and CCDC8. Only a few 3‐M syndrome patients have been reported in Chinese population.

Methods

Children with unexplained severe short stature, facial dysmorphism, and normal intelligence in two Chinese families and their relatives were enrolled. Trio‐whole‐exome sequencing (trio‐WES) and pathogenicity prediction analysis were conducted on the recruited patients. A conservative analysis of the mutant amino acid sequences and function prediction analysis of the wild‐type (WT) and mutant CUL7 protein were performed.

Results

We identified a homozygous missense variant (NM_014780.4: c.4898C > T, p.Thr1633Met) in CUL7 gene in a 6‐month‐old female infant from a non‐consanguineous family, and a homozygous frameshift variant (NM_014780.4: c.3722_3749 dup GGCTGGCACAGCTGCAGCAATGCCTGCA, p. Val1252Glyfs*23) in CUL7 gene in two affected siblings from a consanguinity family. These two variants may affect the properties and structure of CUL7 protein.

Conclusion

These two rare variants were observed in Chinese population for the first time and have not been reported in the literature. Our findings expand the variant spectrum of 3‐M syndrome in Chinese population and provide valuable insights into the early clinical manifestations and pathogenesis of 3‐M syndrome for pediatricians and endocrinologists.

Further expanding the mutational spectrum and investigation of genotype-phenotype correlation in 3M syndrome

3M syndrome is characterized by severe pre- and postnatal growth retardation, typical facial features, and normal intelligence. Homozygous or compound heterozygous mutations in either CUL7, OBSL1, or CCDC8 have been identified in the etiology so far. Clinical and molecular features of 24 patients (23 patients and a fetus) from 19 unrelated families with a clinical diagnosis of 3M syndrome were evaluated and genotype-phenotype correlations were investigated with the use of DNA sequencing, chromosomal microarray, and whole exome sequencing accordingly. A genetic etiology could be established in 20 patients (n = 20/24, 83%). Eleven distinct CUL7 or OBSL1 mutations, among which eight was novel, were identified in 18 patients (n = 18/24, 75%). Ten patients had CUL7 (n = 10/18, 56%) while eight had OBSL1 (n = 8/18, 44%) mutations. Birth weight and height standard deviation scores at admission were significantly (p < 0.05) lower in patients with CUL7 mutation compared to that of patients with OBSL1 mutation. Two patients with a similar phenotype had a de novo 20p13p deletion involving BMP2. No genetic etiology could be established in four patients (n = 4/28, 17%). This study yet represents the largest cohort of 3M syndrome patients from a single center in Turkey. Microdeletions involving BMP2 may cause a phenotype similar to 3M syndrome with some distinctive features. Larger cohort of patients are required to establish genotype-phenotype correlations in 3M syndrome.

Nonclassical GH Insensitivity: Characterization of Mild Abnormalities of GH Action

GH insensitivity (GHI) presents in childhood with growth failure and in its severe form is associated with extreme short stature and dysmorphic and metabolic abnormalities. In recent years, the clinical, biochemical, and genetic characteristics of GHI and other overlapping short stature syndromes have rapidly expanded. This can be attributed to advancing genetic techniques and a greater awareness of this group of disorders. We review this important spectrum of defects, which present with phenotypes at the milder end of the GHI continuum. We discuss their clinical, biochemical, and genetic characteristics. The objective of this review is to clarify the definition, identification, and investigation of this clinically relevant group of growth defects. We also review the therapeutic challenges of mild GHI.

Prenatal and early diagnosis of Chinese 3-M syndrome patients with novel pathogenic variants

BACKGROUND

3-M syndrome is a clinically recognizable yet under-diagnosed primordial growth retardation disorder. Molecular testing for CUL7, OBSL1 or CCDC8 genes can provide confirmed diagnosis for patients at prenatal or early age. So far, the clinical and molecular features of Chinese 3-M syndrome patients have not been reported.

METHODS

In this article, the authors performed prenatal and early diagnosis of Chinese patients with 3-M syndrome by Next-Generation Sequencing.

RESULTS

The authors reported six unrelated Chinese 3-M syndrome patients. Five of the six patients were diagnosed before two years of age including one prenatal case. The authors identified six novel pathogenic variants and five previously reported pathogenic variants. The authors' clinical evaluations indicated that Chinese 3-M syndrome patients share similar recognizable features as those reported in patients of other ethnic background. The authors noticed some uncommon features in this small cohort of Chinese patients such as delayed motor development at early ages, undelayed bone age and presence of lower eyelid fat pads.

CONCLUSION

The authors' study of Chinese 3-M syndrome patients revealed novel mutations and clinical phenotypes.

Recurrence-associated gene signature optimizes recurrence-free survival prediction of colorectal cancer

High throughput gene expression profiling has showed great promise in providing insight into molecular mechanisms. Metastasis‐related mRNAs may potentially enrich genes with the ability to predict cancer recurrence, therefore we attempted to build a recurrence‐associated gene signature to improve prognostic prediction of colorectal cancer (CRC). We identified 2848 differentially expressed mRNAs by analyzing CRC tissues with or without metastasis. For the selection of prognostic genes, a LASSO Cox regression model (least absolute shrinkage and selection operator method) was employed. Using this method, a 13‐mRNA signature was identified and then validated in two independent Gene Expression Omnibus cohorts. This classifier could successfully discriminate the high‐risk patients in discovery cohort [hazard ratio (HR) = 5.27, 95% confidence interval (CI) 2.30–12.08, P < 0.0001). Analysis in two independent cohorts yielded consistent results (GSE14333: HR = 4.55, 95% CI 2.18–9.508, P < 0.0001; GSE33113: HR = 3.26, 95% CI 2.16–9.16, P = 0.0176). Further analysis revealed that the prognostic value of this signature was independent of tumor stage, postoperative chemotherapy and somatic mutation. Receiver operating characteristic (ROC) analysis showed that the area under ROC curve of this signature was 0.8861 and 0.8157 in the discovery and validation cohort, respectively. A nomogram was constructed for clinicians, and did well in the calibration plots. Furthermore, this 13‐mRNA signature outperformed other known gene signatures, including oncotypeDX colon cancer assay. Single‐sample gene‐set enrichment analysis revealed that a group of pathways related to drug resistance, cancer metastasis and stemness were significantly enriched in the high‐risk patients. In conclusion, this 13‐mRNA signature may be a useful tool for prognostic evaluation and will facilitate personalized management of CRC patients.