Children with short-limbed short stature in pediatric endocrinological services in Japan

Radiological characteristics of skeletal growth in neonates and infants with achondroplasia

Achondroplasia (ACH) is the most common form of skeletal dysplasia characterized by a rhizomelic short stature. Radiological skeletal findings in pediatric and adult patients with ACH include short long bones, a relatively longer fibula compared to the tibia, a narrow lumbar interpedicular distance, and a hypoplastic iliac wing. Nonetheless, the characteristics of skeletal growth during the neonatal and infantile periods have scarcely been explored. Therefore, this retrospective study aimed to analyze the radiological skeletal growth during the neonatal and infantile periods in 41 Japanese patients with genetically confirmed ACH. The length of long bones in the upper and lower limbs and the lumbar interpedicular distances at L1 and L4 were measured. These parameters showed significant positive correlations with age. The upper segment-to-lower segment ratio in the lower limbs resembled the data of healthy controls from previous reports. The L1/L4 and fibula/tibia ratios increased with age, suggesting that some representative skeletal phenotypes of ACH were less distinct during the neonatal and infantile periods. In conclusion, for the first time, this study radiologically characterized skeletal growth during the neonatal and infantile periods of patients with genetically confirmed ACH.

Severe Combined Immunodeficiency-Classification, Microbiology Association and Treatment

Severe combined immunodeficiency (SCID) is a primary inherited immunodeficiency disease that presents before the age of three months and can be fatal. It is usually due to opportunistic infections caused by bacteria, viruses, fungi, and protozoa resulting in a decrease in number and impairment in the function of T and B cells. Autosomal, X-linked, and sporadic forms exist. Evidence of recurrent opportunistic infections and lymphopenia very early in life should prompt immunological investigation and suspicion of this rare disorder. Adequate stem cell transplantation is the treatment of choice. This review aimed to provide a comprehensive approach to the microorganisms associated with severe combined immunodeficiency (SCID) and its management. We describe SCID as a syndrome and summarize the different microorganisms that affect children and how they can be investigated and treated.

Molecular genetic analysis and growth hormone response in patients with syndromic short stature

BACKGROUND

Syndromic short stature is a genetic and phenotypic heterogeneous disorder with multiple causes. This study aims to identify genetic causes in patients with syndromic short stature of unknown cause and evaluate the efficacy of the growth hormone response.

METHODS

Trio-whole-exome sequencing was applied to identify pathogenic gene mutations in seven patents with short stature, multiple malformations, and/or intellectual disability. Whole-genome low-coverage sequencing was also performed to identify copy number variants in three patients with concurrent intellectual disability. Recombinant human growth hormone was administered to improve height in patients with an identified cause of syndromic short stature.

RESULTS

Of the seven patients, three pathogenic/likely pathogenic gene mutations, including one FGFR3 mutation (c.1620C>A p.N540K), one novel GNAS mutation (c.2288C>T p.A763V), and one novel TRPS1 mutation (c.2527_c.2528dupTA p.S843fsX72), were identified in three patients. No copy number variants were identified in the three patients with concurrent intellectual disability. The proband with an FGFR3 mutation, a female 4 and 3/12 years of age, was diagnosed with hypochondroplasia. Long-acting growth hormone improved her height from 85.8 cm [- 5.05 standard deviation (SD)] to 100.4 cm (- 4.02 SD), and her increased height SD score (SDS) was 1.03 after 25 months of treatment. The proband with a GNAS mutation, a female 12 and 9/12 years of age, was diagnosed with pseudohypoparathyroidism Ia. After 14 months of treatment with short-acting growth hormone, her height improved from 139.3 cm (- 2.69 SD) to 145.0 cm (- 2.36 SD), and her increased height SDS was 0.33.

CONCLUSIONS

Trio-whole-exome sequencing was an important approach to confirm genetic disorders in patients with syndromic short stature of unknown etiology. Short-term growth hormone was effective in improving height in patients with hypochondroplasia and pseudohypoparathyroidism Ia.

A Review of Three Chinese Cases of Acromicric/Geleophysic Dysplasia with FBN1 Mutations

Objective

This study aims to explore the clinical features and molecular diagnosis of FBN1-related acromelic dysplasia in Chinese patients.

Methods

The clinical and genetic features of three FBN1-related acromicric dysplasia (AD)/geleophysic dysplasia (GD) Chinese patients from two families were reviewed, and comprehensive medical evaluations were performed. Targeted next-generation sequencing was used to detect genetic mutations associated with short statures, including FBN1. Sanger sequencing was used to determine the de novo mutation origin.

Results

Patient 1 presented with short stature, short and stubby hands and feet, mild facial dysmorphism, hepatomegaly, delayed bone age and beak-like femoral heads. Patient 2 and this patient’s father merely presented with short stature, wide and short hands, and beak-like femoral heads. One novel mutation, c.5272G>T(p.D1758Y), and one known mutation, c.5183C>T(p.A1728V), were identified in these patients.

Conclusion

The clinical features varied among these patients. The variant c.5272G>T(p.D1758Y) is a novel mutation.

Three cases of Japanese acromicric/geleophysic dysplasia with FBN1 mutations: a comparison of clinical and radiological features

Acromicric dysplasia (AD) and geleophysic dysplasia (GD) are rare skeletal dysplasias characterized by short stature, acromelia, joint contracture, hepatomegaly, hoarseness and respiratory distress. Compared with GD, AD presents with milder clinical and radiological features. Radiological findings of AD and GD consist of shortened tubular bones of the hands and feet, and deformed capital femoral epiphyses. The genetic cause of AD and some cases of GD was shown to be mutations in the transforming growth factor (TGF) β-binding protein-like domain 5 of the fibrillin 1 gene (FBN1), which is also mutated in Marfan syndrome. In the present study, we report and compare the highly varied clinical and radiological features of three Japanese AD/GD children. Our patients, harboring FBN1 mutations p.Tyr1699Cys, p.Ser1750Arg, and p.Gly1762Ser, shared common clinical symptoms such as severe short stature, acromelia and hepatomegaly. Short tubular bones of hands and deformities of femur heads are common radiological features of our patients.

A pilot study of gene testing of genetic bone dysplasia using targeted next-generation sequencing

Molecular diagnosis of genetic bone dysplasia is challenging for non-expert. A targeted next-generation sequencing technology was applied to identify the underlying molecular mechanism of bone dysplasia and evaluate the contribution of these genes to patients with bone dysplasia encountered in pediatric endocrinology. A group of unrelated patients (n=82), characterized by short stature, dysmorphology and X-ray abnormalities, of which mucopolysacharidoses, GM1 gangliosidosis, mucolipidosis type II/III and achondroplasia owing to FGFR3 G380R mutation had been excluded, were recruited in this study. Probes were designed to 61 genes selected according to the nosology and classification of genetic skeletal disorders of 2010 by Illumina's online DesignStudio software. DNA was hybridized with probes and then a library was established following the standard Illumina protocols. Amplicon library was sequenced on a MiSeq sequencing system and the data were analyzed by MiSeq Reporter. Mutations of 13 different genes were found in 44 of the 82 patients (54%). Mutations of COL2A1 gene and PHEX gene were found in nine patients, respectively (9/44=20%), followed by COMP gene in 8 (18%), TRPV4 gene in 4 (9%), FBN1 gene in 4 (9%), COL1A1 gene in 3 (6%) and COL11A1, TRAPPC2, MATN3, ARSE, TRPS1, SMARCAL1, ENPP1 gene mutations in one patient each (2% each). In conclusion, mutations of COL2A1, PHEX and COMP gene are common for short stature due to bone dysplasia in outpatient clinics in pediatric endocrinology. Targeted next-generation sequencing is an efficient way to identify the underlying molecular mechanism of genetic bone dysplasia.