Osteogenesis Imperfecta

Rare coexistence of hypopituitarism with osteogenesis imperfecta - A double-trouble for bone

Osteogenesis imperfecta (OI) commonly involving defects in COL1A1 and COL1A2 is a rare hereditary disease of bone fragility affecting 6-7 per 100,000 population. On the other hand, hypopituitarism is a separate entity that manifests with reduced levels of pituitary hormones. The cooccurrence of these two is seldom reported previously in literature as a deviation from Occam's razor. Here, we reported a case of pathological fracture in a 31-year-old male who had blue sclera and secondary adrenal insufficiency, hypogonadotropic hypogonadism, and growth hormone deficiency along with primary autoimmune hypothyroidism. Diagnosis of OI was suggested by heterozygous missense variant in exon 40 of the COL1A2 gene (chr7: g.94423092G > A; Depth: 99×) that resulted in the amino acid substitution of Serine for Glycine at codon 847. Replacement of glucocorticoid, levothyroxine, and testosterone was started along with antiresorptive therapy for better bone health outcomes.

Current Overview of Osteogenesis Imperfecta

Osteogenesis imperfecta (OI), or brittle bone disease, is a heterogeneous disorder characterised by bone fragility, multiple fractures, bone deformity, and short stature. OI is a heterogeneous disorder primarily caused by mutations in the genes involved in the production of type 1 collagen. Severe OI is perinatally lethal, while mild OI can sometimes not be recognised until adulthood. Severe or lethal OI can usually be diagnosed using antenatal ultrasound and confirmed by various imaging modalities and genetic testing. The combination of imaging parameters obtained by ultrasound, computed tomography (CT), and magnetic resource imaging (MRI) can not only detect OI accurately but also predict lethality before birth. Moreover, genetic testing, either noninvasive or invasive, can further confirm the diagnosis prenatally. Early and precise diagnoses provide parents with more time to decide on reproductive options. The currently available postnatal treatments for OI are not curative, and individuals with severe OI suffer multiple fractures and bone deformities throughout their lives. In utero mesenchymal stem cell transplantation has been drawing attention as a promising therapy for severe OI, and a clinical trial to assess the safety and efficacy of cell therapy is currently ongoing. In the future, early diagnosis followed by in utero stem cell transplantation should be adopted as a new therapeutic option for severe OI.

Mother and child with osteogenesis imperfecta type III. Pregnancy management, delivery, and outcome

Objectives

Thanks to the advances of modern medicine it has become possible to reach a fertile age even in the case of serious illnesses, enabling those patients to realize their desire to have children. This is also the case with the extremely heterogeneous, often autosomal dominantly inherited osteogenesis imperfecta. Due to a disruption in collagen synthesis those patients are faced with multiple fractures, spinal deformities and a decrease in pulmonary capacity throughout the course of their lives, depending on the subtype and severity of the disease. Obstetricians as well as anesthetists face major interdisciplinary challenges in the case of a pregnancy in those patients because of pregnancy-associated risks like uterine rupture, preterm birth and postpartum hemorrhage as well as risks associated with the nature of osteogenesis imperfecta itself, like bone fractures, spinal deformities and decreased mobility in the course of the progressing pregnancy. Mode of delivery should be planned individually in order to minimize maternal morbidity and mortality. In cases in which the fetus is as well affected by the disease, this aspect must be taken into consideration when it comes to supervision of pregnancy and planning of the birth mode.

Case presentation

We report the case of a woman with osteogenesis imperfecta type III who spontaneously conceived a pregnancy with a fetus who was also affected by the genetic disease. This constellation has up to now been reported by only few sources and requires supervision by an experienced perinatal center.

Conclusions

Osteogenesis imperfecta is not an exclusion diagnosis for family planning and a successful delivery. Nevertheless, depending on the form of the disease, mother and child can be severely affected by the disturbed collagen synthesis. Each patient has to be individually advised and cared for with the specific risks due to the type of Osteogenesis imperfecta. In the case of type III, due to extreme scoliosis, pelvic deformity and small growth, only a primary cesarean section can be performed.

Osteogenesis Imperfecta Due to Combined Heterozygous Mutations in Both COL1A1 and COL1A2, Coexisting With Pituitary Stalk Interruption Syndrome

Osteogenesis imperfecta (OI) is a hereditary connective tissue disorder, characterized by reduced bone content, fractures and skeletal malformation due to abnormal synthesis or dysfunction of type I collagen protein. Pituitary stalk interruption syndrome (PSIS) is usually associated with environmental and hereditary factors. Here, we report a rare case of OI and PSIS co-occurrence. A 19-year-old male patient sought treatment for growth delay and absent secondary sexual characteristics. Hormone measurements indicated the presence of hypopituitarism (secondary hypothyroidism, growth hormone deficiency, ACTH-cortisol hormone deficiency, hypogonadotropic hypogonadism). Pituitary magnetic resonance imaging indicated reduced morphology of the anterior lobe, absence of the pituitary stalk, and ectopic displacement of the posterior lobe to the infundibulum, supporting a diagnosis of PSIS. In addition, the patient, his monozygotic twin brother (no evidence of PSIS), and their mother all presented blue sclera and susceptibility to bone fractures before adulthood. Next-generation sequencing demonstrated that the family had compound heterozygous mutations in COL1A1 and COL1A2, with no known mutations related to PSIS, pituitary hormone deficiency (PHD), or holoprosencephaly (HPE). The mother experienced breech and natural delivery of the patient and his brother, respectively. Thus, we deduced that the patient's PSIS might have resulted from breech delivery. Although we cannot exclude the possibility that the proband might have an undetected genetic abnormality causing PSIS or increasing his susceptibility to damage to the hypothalamic-pituitary region due to the limitation of exome sequencing, this rare case suggests that breech delivery in the newborn with OI might be related to PSIS.