Clinical charts for surveillance of growth and body proportion development in achondroplasia and examples of their use

Relevance of Extending FGFR3 Gene Analysis in Osteochondrodysplasia to Non-Coding Sequences: A Case Report

Skeletal dysplasia, also called osteochondrodysplasia, is a category of disorders affecting bone development and children's growth. Up to 552 genes, including fibroblast growth factor receptor 3 (FGFR3), have been implicated by pathogenic variations in its genesis. Frequently identified causal mutations in osteochondrodysplasia arise in the coding sequences of the FGFR3 gene: c.1138G>A and c.1138G>C in achondroplasia and c.1620C>A and c.1620C>G in hypochondroplasia. However, in some cases, the diagnostic investigations undertaken thus far have failed to identify the causal anomaly, which strengthens the relevance of the diagnostic strategies being further refined. We observed a Caucasian adult with clinical and radiographic features of achondroplasia, with no common pathogenic variant. Exome sequencing detected an FGFR3(NM_000142.4):c.1075+95C>G heterozygous intronic variation. In vitro studies showed that this variant results in the aberrant exonization of a 90-nucleotide 5' segment of intron 8, resulting in the substitution of the alanine (Ala359) for a glycine (Gly) and the in-frame insertion of 30 amino acids. This change may alter FGFR3's function. Our report provides the first clinical description of an adult carrying this variant, which completes the phenotype description previously provided in children and confirms the recurrence, the autosomal-dominant pathogenicity, and the diagnostic relevance of this FGFR3 intronic variant. We support its inclusion in routinely used diagnostic tests for osteochondrodysplasia. This may increase the detection rate of causal variants and therefore could have a positive impact on patient management. Finally, FGFR3 alteration via non-coding sequence exonization should be considered a recurrent disease mechanism to be taken into account for new drug design and clinical trial strategies.

A scoping review of nutrition issues and management strategies in individuals with skeletal dysplasia

PURPOSE

Skeletal dysplasia are heterogeneous conditions affecting the skeleton. Common nutrition issues include feeding difficulties, obesity, and metabolic complications. This systematic scoping review aimed to identify key nutrition issues, management strategies, and gaps in knowledge regarding nutrition in skeletal dysplasia.

METHODS

The databases Ovid MEDLINE, Ovid EMBASE, Ebsco CINAHL, Scopus, and Cochrane Central Register of Controlled Trials and Database of Systematic Reviews were searched. Reference lists and citing literature for included studies were searched. Eligible studies included participants with skeletal dysplasia and described: anthropometry, body composition, nutrition-related biochemistry, clinical issues, dietary intake, measured energy or nutrition requirements, or nutrition interventions.

RESULTS

The literature search identified 8509 references from which 138 studies were included (130 observational, 3 intervention, 2 systematic reviews, and 3 clinical guidelines). Across 17 diagnoses identified, most studies described osteogenesis imperfecta (n = 50) and achondroplasia or hypochondroplasia (n = 47). Nutrition-related clinical issues, biochemistry, obesity, and metabolic complications were most commonly reported, and few studies measured energy requirements (n = 5).

CONCLUSION

Nutrition-related comorbidities are documented in skeletal dysplasia; yet, evidence to guide management is scarce. Evidence describing nutrition in rarer skeletal dysplasia conditions is lacking. Advances in skeletal dysplasia nutrition knowledge is needed to optimize broader health outcomes.

The past, present, and future of child growth monitoring: A review and primer for clinical genetics

Child growth measurements are critical vital signs to track, with every individual child growth curve potentially revealing a story about a child's health and well-being. Simply put, every baby born requires basic building blocks to grow and thrive: proper nutrition, love and care, and medical health. To ensure that every child who is missing one of these vital aspects is identified, growth is traditionally measured at birth and each well-child visit. While the blue and pink growth curves appear omnipresent in pediatric clinics, it is surprising to realize that their use only became standard of care in 1977 when the National Center for Health Statistics (NCHS) adopted the growth curve as a clinical tool for health. Behind this practice lies a socioeconomically, culturally, and politically complex interplay of individuals and institutions around the world. In this review, we highlight the often forgotten past, current state of practice, and future potential of this powerful clinical tool: the growth reference chart, with a particular focus on clinical genetics practice. The goal of this article is to understand ongoing work in the field of anthropometry (the scientific study of human measurements) and its direct impact on modern pediatric and genetic patient care.

Lifetime impact of achondroplasia study in Europe (LIAISE): findings from a multinational observational study

BACKGROUND

Achondroplasia, caused by a pathogenic variant in the fibroblast growth factor receptor 3 gene, is the most common skeletal dysplasia. The Lifetime Impact of Achondroplasia Study in Europe (LIAISE; NCT03449368) aimed to quantify the burden of achondroplasia among individuals across a broad range of ages, including adults.

METHODS

Demographic, clinical and healthcare resource use data were collected from medical records of achondroplasia patients enrolled in 13 sites across six European countries in this retrospective, observational study. Descriptive statistics or event rates per 100 person-years were calculated and compared across age groups as well as by history of limb lengthening. Patient-reported outcomes (quality of life [QoL], pain, functional independence, work productivity and activity impairments) were evaluated using questionnaires at the time of enrolment. An exploratory analysis investigated correlations between height (z-score or centimetres) and patient-reported outcomes.

RESULTS

Overall, 186 study patients were included, with a mean age of 21.7 ± 17.3 years (range 5.0-84.4). At least one complication or surgery was reported for 94.6% and 72.0% of patients, respectively, at a rate of 66.6 and 21.5 events per 100 person-years. Diverse medical and surgical complications were reported for all ages in a bimodal distribution, occurring more frequently in the youngest and oldest age groups. A total of 40 patients had previously undergone limb lengthening (capped at 20% per the study protocol). The most frequent surgery types varied by age, in line with complication profiles. Healthcare resource use was high across all age groups, especially among the youngest and oldest individuals, and did not differ substantially according to history of limb lengthening. Compared to general population values, patients reported impaired QoL particularly for physical functioning domains. In addition, patients reported difficulty carrying out daily activities independently and pain starting in childhood. Patient height correlated with multiple patient-reported outcomes.

CONCLUSIONS

The findings of this study suggest that, across an individual's lifetime, achondroplasia is associated with multisystem complications, reduced QoL and functionality, and increased pain. These results highlight the large amount of healthcare resources that individuals with achondroplasia require throughout their lifespans and provide novel insights into current achondroplasia management practices across Europe. Trial registration ClinicalTrials.gov, NCT03449368, Submitted 14 December 2017 - prospectively registered, https://clinicaltrials.gov/ct2/show/record/NCT03449368.

Growth Modulation by Tension Band Plate in Achondroplasia With Varus Knee Deformity: Comparison of Gait Analysis Measurements

BACKGROUND

Limited evidence exists concerning growth modulation by tension band plate (TBP) to correct varus deformity in patients with achondroplasia with limited growth due to FGFR3 gene mutation. We evaluated the efficacy of TBP in children with achondroplasia with genu varum and reported the static radiographic and dynamic motion data to determine parameters that impact the rate of deformity correction.

METHODS

Patients with achondroplasia with genu varum who underwent TBP surgery for growth modulation were studied. Those with at least 1 year of follow-up with TBP were included. Radiographic parameters were measured. Growth velocity of femoral/tibial length was calculated separately. Patients were deemed successful or unsuccessful. Spearman correlation analysis and Student t test were used to describe statistical results.

RESULTS

Twenty-two patients (41 limbs; 12 girls) fulfilled our criteria. Mean age at TBP surgery was 7.6±2.4 years. Thirty-six femoral TBP and 41 tibial TBP were in place for 24.5±9.7 months. Mean mechanical axis deviation, mechanical lateral distal femoral angle, and medial proximal tibial angle preoperatively were 30.1±7.6 mm, 97.2±6.4, and 80.3±4.3 degrees, and 11±15.6 mm, 87.4±5.9, and 84.7±5.3 degrees at last follow-up ( P <0.001). Fifteen limbs were successfully straightened; 4 limbs were in more varus than the initial deformity. Twenty-four limbs with TBP were still undergoing correction. In successful limbs, mean age at surgery was 6.5±1.7 years and duration of TBP was 29.9±7.8 months. In 4 unsuccessful limbs, mean age at surgery was 11.7±1.2 years. Analysis in the gait laboratory included physical examination with the measurement of knee varus and kinematic varus based on a posterior view static standing photograph. Photographic measurement of varus was higher than the radiographic measurement.

CONCLUSIONS

Growth modulation by TBP surgery is a reliable and simple technique to correct genu varum in achondroplasia. An early age at TBP implementation (mean: 6.5 y) is crucial to successfully correct the varus knee deformity. Furthermore, we recommend early and regular surveillance of achondroplasia for progressive varus knee deformity.

LEVEL OF EVIDENCE

Level IV-cohort study.

Australian guidelines for the management of children with achondroplasia

Achondroplasia is the most common form of skeletal dysplasia. In addition to altered growth, children and young people with achondroplasia may experience medical complications, develop and function differently to others and require psychosocial support. International, European and American consensus guidelines have been developed for the management of achondroplasia. The Australian focused guidelines presented here are designed to complement those existing guidelines. They aim to provide core care recommendations for families and clinicians, consolidate key resources for the management of children with achondroplasia, facilitate communication between specialist, local teams and families and support delivery of high-quality care regardless of setting and geographical location. The guidelines include a series of consensus statements, developed using a modified Delphi process. These statements are supported by the best available evidence assessed using the National Health and Medicine Research Council's criteria for Level of Evidence and their Grading of Recommendations Assessment, Development and Evaluation (GRADE). Additionally, age specific guides are presented that focus on the key domains of growth, medical, development, psychosocial and community. The guidelines are intended for use by health professionals and children and young people with achondroplasia and their families living in Australia.

Spinal canal stenosis in children with achondroplasia: the role of augmentation laminoplasty-a 15-year single institution experience

PURPOSE

Achondroplasia typically results in compressive spinal canal stenosis in one-third of children, but rare under the age of 15 years. Laminectomy is the mainstay of treatment but this leads to instability and progressive deformity requiring complex fixation. In order to reduce that risk, we developed a novel modified augmented laminoplasty that increases spinal canal diameter while preserving the posterior column stability.

METHODS

All laminoplasty cases for spinal compressive achondroplasia from 2006 to 2020 were included. Ten augmentation laminoplasty procedures were performed in 7 children with regular clinical and radiological post-operative follow-up. Kyphotic deformity and clinical outcomes (neurological and urological) were evaluated.

RESULTS

At presentation, clinical features included radiculopathy, neurogenic claudication or acute cauda equina compression with sphincter dysfunction. The average age at initial surgery was 11.2 (range 5-16) with a mean follow-up of 5 (range 2-8) years. All patients demonstrated improvement in neurogenic claudication symptoms after surgery; however, bladder dysfunction persisted in some children. In one child, cervical and lumbar augmentation laminoplasties were performed for concomitant disease. Augmentation laminoplasty effectively prevented deformity progression over time in all cases except one where a further revision laminoplasty with extension was required for screw loosening. Despite this, progressive symptomatic kyphotic deformity led to a 360° fixation. Minor complications included one dural breach (repaired intraoperatively) and one superficial wound infection.

CONCLUSION

Augmentation laminoplasty is a viable surgical option following laminectomy in achondroplasia patients as an alternative to surgical fixation. Fixation can be reserved for cases where there is progressive deformity and kyphosis.

Achondroplasia: Update on diagnosis, follow-up and treatment

Achondroplasia requieres multidisciplinary follow-up, with the aim of preventing and managing complications, improving the quality of life of people who suffer from it and favoring their independence and social inclusion. This review is justified by the multiple publications generated in recent years that have carried out a change in its management. Different guidelines and recommendations have been developed, among which the one made by the American Academy of Pediatrics in 2005 recently updated (2020), the Japanese guide (2020), the first European Consensus (2021) and the International Consensus on the diagnosis, approach multidisciplinary approach and management of individuals with achondroplasia throughout life (2021). However, and despite these recommendations, there is currently a great worldwide variability in the management of people with achondroplasia, with medical, functional and psychosocial consequences in patients and their families. Therefore, it is essential to integrate these recommendations into daily clinical practice, taking into account the particular situation of each health system.

International Consensus Statement on the diagnosis, multidisciplinary management and lifelong care of individuals with achondroplasia

Achondroplasia, the most common skeletal dysplasia, is characterized by a variety of medical, functional and psychosocial challenges across the lifespan. The condition is caused by a common, recurring, gain-of-function mutation in FGFR3, the gene that encodes fibroblast growth factor receptor 3. This mutation leads to impaired endochondral ossification of the human skeleton. The clinical and radiographic hallmarks of achondroplasia make accurate diagnosis possible in most patients. However, marked variability exists in the clinical care pathways and protocols practised by clinicians who manage children and adults with this condition. A group of 55 international experts from 16 countries and 5 continents have developed consensus statements and recommendations that aim to capture the key challenges and optimal management of achondroplasia across each major life stage and sub-specialty area, using a modified Delphi process. The primary purpose of this first International Consensus Statement is to facilitate the improvement and standardization of care for children and adults with achondroplasia worldwide in order to optimize their clinical outcomes and quality of life.

Simultaneous Bilateral Femoral and Tibial Lengthening in Achondroplasia

Previous studies on lengthening for achondroplasia have reported bilateral extensive femoral lengthening followed by bilateral extensive tibial lengthening. To decrease trauma on soft tissues and joints, we propose bilateral simultaneous moderate femoral lengthening and moderate tibial lengthening followed by a similar repeat lengthening a few years later. Fifty patients with achondroplasia underwent 65 simultaneous bilateral femoral and tibial lengthening procedures. Segment lengthening amount and adverse events were obtained from medical records. Mean follow-up after bone healing was 35.6 months. Mean tibial lengthening was 52 mm; mean femoral lengthening was 72 mm. Average healing index was 1.4 months/cm for the tibia and 1 month/cm for the femur. Mean duration of treatment with external fixation was 6.7 months (range, 4.4-10.5 months). Thirty-eight (76%) of 50 patients experienced one or more adverse events during lengthening. We observed 78 adverse events, 35 (45%) of which required additional surgical procedures. All resolved by the end of treatment. Mechanical axis deviation improved from a mean of 15 mm medially to 8 mm medially. Simultaneous lengthening of four segments in patients with achondroplasia is a feasible strategy. Compared with isolated femoral or tibial lengthening, distributing the lengthening between the femur and tibia decreases total external fixator time.