Diego Vélasquez, don Sebastian de Morra
ACHONDROPLASIA
Geert Mortier, MD, PhD Department of Medical Genetics
Antwerp University Hospital University of Antwerp
GENOMED Centre of Excellence
• autosomal dominant condition • recurrent mutation (p.G380R) in FGFR3 gene • most common form of short limb dwarfism (1/10.000-1/30.000)
• major clinical features: - prenatal onset of disproportionate short stature - macrocephaly, low nasal bridge, frontal bossing - short limbs with redundant skin folds, trident hand - ligamentous laxity in knees, genua vara - normal intelligence - adult height: males 131 ± 5,6 cm females 124 ± 5,9 cm
• major radiographic features:
- shortening of tubular bones (all segments involved) - platyspondyly, bullet-shaped vertebrae, posterior scalloping - interpedicular narrowing - abnormal pelvis with small iliac wings, flat acetabular roofs (trident) - lumbar hyperlordosis
Achondroplasia
FGFR3
cell
mem
bran
e
intracellular extracellular
SP: signal peptide Ig: immunoglobuline-like domain TM: transmembrane domain
Structure of the FGFR3 protein
p.G380R mutation in achondroplasia
Current care and management
• no cure • genetic counseling • growth hormone treatment: effect on adult height?1 • limb lengthening: final height up to + 20 cm • new drugs in the pipeline • now mainly prevention and treatment of complications • lack of evidence-based guidelines • need for multidisciplinary approach!
1 Miccoli M et al. Horm Res Paediatr 2016;86:27-34
• key concerns in the infant and toddler: - ventriculomegaly/true hydrocephaly (very rare) - spinal cord compression at cervicomedullary junction (small foramen magnum)
- sudden infant death (rare) - thoracolumbar kyphosis - middle ear effusions and infections - sleep apnea (obstructive and/or central)
• key concerns in the older child:
- upper airway and ENT infections - sleep apnea - obesity - angular deformities of the lower limb (genua vara)
• key concerns in the adolescent and adult
- lumbar spinal stenosis - back pain - peripheral nerve compression
Areas of concern in achondroplasia
Femoral Lengthening in Achondroplasia
• Correct Coxa vara • Correct FFD hip • Decrease hyperlordosis
• Pharma-ledcurrentstudies– Biomarin901–naturalhistorystudy– Biomarin301–RCTofvosori@de(C-nature@cpep@de)in5-18yearagegroup
– Therachon–TA-46(FGFR3ligandtrap)–phase1started• Pharma-ledindevelopment
– Biomarin205-RCTofvosori@dein2-5yearagegroup– Ascendis–TransConCNP–sustainedreleaseCNP– Ribomic–RBM007–an@-FGF2aptamer
• Inves@gator-ledstudies
– Meclozine(preclinical)
Clinical trials in achondroplasia
Courtesy N Bishop
Natriure@cpep@desystem
cGKII (cGMP dependent kinase II) � Acts downstream of cGMP � cGKII-/- mice
� Dwarfism
� Inhibits the MAPK pathway � Overactivation in achondroplasia
� Caused by gain-of-function mutations in FGFR3 � Short-limb dwarfism
è CNP possible therapeutic target
BMN-111
https://globenewswire.com/news-release/2015/06/17/745424/10138876/en/BMN-111-vosoritide-Improves-Growth-Velocity-in-Children-With-Achondroplasia-in-Phase-2-Study.html
https://globenewswire.com/news-release/2015/06/17/745424/10138876/en/BMN-111-vosoritide-Improves-Growth-Velocity-in-Children-With-Achondroplasia-in-Phase-2-Study.html
Take home messages
• frequent skeletal dysplasia • significant morbidity (more than being short…) • need for close follow-up early on in life • multidisciplinary approach • use of achondroplasia-specific charts (growth and development) • need for good (evidence-based) clinical guidelines • new drugs maybe promising (not only for stature?)