The kyphoscoliotic type of the Ehlers-Danlos syndrome (EDS type VIA) is a rare autosomal recessive connective tissue disorder, which in the first years of life mainly affects the musculoskeletal system. Infants affected with EDS type VIA present with moderate to severe generalized muscle hypotonia, and with skeletal findings such as kyphoscoliosis and joint hyperextensibility which are also common to neuromuscular disorders such as congenital myopathies including Bethlem myopathy and Ullrich muscular dystrophy  as well as lower motor neuron diseases, especially when deformities of the feet and joint dislocations coexist. In all patients documented in the literature [2, 11] kyphoscoliosis is usually present at birth, and hypotonia in conjunction with the inability to stabilize the joints, due to laxity of the connective tissue, leads to a delay in gross motor development in the first years of life. The kyphoscoliotic form of EDS can be diagnosed by non invasive biochemical analysis of urinary pyridinolines; molecular analysis of the PLOD1 gene can be added for future prenatal diagnosis. Variability of the clinical phenotype is suspected even though limited data is available about the spectrum of the disease severity; in particular little data is available about the presentation in adulthood. Thus, here we report on the broad clinical spectrum found in 12 index patient and 3 relatives diagnosed between the age of 7 months and 27 years in order to emphasize the clinical features that add insight into the clinical variability of the disease. Furthermore, we focus on biochemical and molecular aspects, as well as electron microscopy findings of relevance for a timely diagnosis.
The newborns with available history and biochemically confirmed EDS type VIA are generally described with hypotonia and delay of motor development in the first few years of life . All but one index case (P2) presented with significant muscular hypotonia that was noted at birth. This patient was first diagnosed at the age of 27 years and his family was not aware of any problems within his first few years of life. We can not exclude however, that this clinical feature was present but further ignored, as it is generally believed that motor development and muscular hypotonia presenting in the neonatal period improve over the course of time even though kyphoscoliosis is usually progressive.
Currently, very little is known about long-term outcome of ambulation in patients with EDS VIA, therefore, we present here for the first time data about the ability of walking in a collective of 15 patients. Notably, one patient was wheel chair bound and never able to walk and two were reported to walk with assistance only. It might be speculated that the absence of neonatal kyphoscoliosis is a positive prognostic factor regarding future ambulation, since all our patients without kyphoscoliosis at birth were able to walk. However, in the light of the small number of affected individuals this assumption might be taken with caution. Based on the results of 3 related individuals from consanguineous parents who shared the mutant PLOD1 genotype, but did not develop the same severity and age of onset of kyphoscoliosis, we conclude that this clinical feature might not correlate with the genotype.
A feature that was present in all patients was smooth velvety skin; it should therefore be included to the specific diseases features/characteristics. In particular, velvety skin texture may help to distinguish EDS, kyphoscolitic form from congenital myopathies.
Kyphoscoliosisis, attributed to muscular hypotonia together with ligamentous laxity, is generally also reported at birth and represents one of the striking hallmarks of this disease; it should prompt clinician to the diagnosis of EDS type VIA as it is usually not found in neuromuscular diseases. Surprisingly, kyphoscoliosis at birth was not reported in 4 of our patients.
However, two of them developed kyphoscoliosis later in life (Table 1), while P2 did not develop any asymmetry of the spine until the age of 27 years. Interestingly, this patient did not present with hypotonia in childhood, in contrast to the other two, suggesting that lack of hypotonia at birth might be a favorable prognostic finding for non developing spine deformity later in life. Indeed, data from PLOD1
mice suggest a direct correlation between lack of kyphosis and absence of muscle hypotonia at birth .
In addition, no association between the presence of kyphoscoliosis at birth and the type of PLOD1 mutation was found in our collective of EDS VIA.
A lack of association between genotype and phenotype has recently been suspected [2, 13] and our findings reflect again the phenomenon of interfamilial and intrafamilial variability of this disorder. The list of disorders where the same mutation presents with a different phenotype is steadily increasing and includes, for example, mutations of COLA1 in osteogenesis imperfecta. Modifying sequence variants within the entire genome, epigenetic factors or environmental factors may be responsible for this observation.
In contrast to other EDS forms such as EDS type VII , hip dislocations at birth seems to be a less common feature, described in only 25% of our patients.
Importantly and adding to the current knowledge of EDS VIA, we noted the occurrence of vascular rupture both, antenatally in one patient (P12) as well as in adulthood as the first clinical symptom (P2). Vascular rupture is by far the major life-threatening complication in this disorder however it is thought to be less frequent than in EDS type IV. Antenatal vascular event was previously reported in two patients with EDS VIA, only . The finding of antenatal vascular events in our EDS VIA collective increases the likelihood of their direct association with EDS VIA. Furthermore, vascular events might be more frequent in EDS VIA than expected. Notably, 15% of PLOD1
mice died at the age of 1-4 months due to aortic dissections, caused most likely by degenerated smooth muscle cells and abnormal collagen fibrils of aortic wall . Thus antenatal vascular events of unknown aetiology should therefore prompt investigations for EDS type VIA, Historically, intellect is reported to be unaffected in kyphoscoliotic type of EDS. Unexpectedly, we found delayed cognitive function in 5 out of 12 index patients, however, except for the patient with antenatal central nervous system vascular event, brain imaging and neurological exam did not reveal an underlying cause for the developmental delay. Whether the impaired cognition is in direct association with EDS VIA or independent and therefore not part of the disease remains to be further investigated. Further, in the context of consanguinity a concomitant disorder must be taken into consideration.
Kyphoscoliotic type of EDS is diagnosed by abnormally elevated ratio of urinary lysyl pyridinolines to hydroxylysyl pyridinoline crosslinks and can be confirmed by mutation analysis of PLOD1. Our results on LP/HP ratios indicate that the ratio is highest in the age group 0-4 year and subsequently decreases, however remains significantly elevated when compared to normal controls. No correlation between LP/HP ratios and genotype were observed. In all but 2 patients molecular analysis of PLOD1 was performed confirming the diagnosis based on pyridinoline ratios in urine (Table 1).
Specific abnormal collagen electron microscopy findings in skin biopsies have been described for classical EDS , EDS VII  and recently also for RIN2-deficient patients . Here we describe typical collagen fibril alterations in skin biopsies of two EDS VIA patients. Abnormal electron microscopy findings (Figure 1) included variable diameters of the collagen fibrils, irregular interfibrillar space in addition to irregular ragged outlines in cross sections. To our knowledge these findings are distinct and have not been described in other subtypes of EDS or other connective tissue disorders. Furthermore, they resemble those described in PLOD1
In summary we present 15 additional individuals with kyphoscoliotic type of EDS. In all but one (sibling of an index case), the diagnosis was made on clinical grounds and subsequently confirmed by analysis of pyridinolines in urine, as well as molecular studies of PLOD1. Determination of urinary pyridinoline cross-links is a fast, non-invasive, simple, and indeed reliable diagnostic test for EDS type VI.
Typical clinical features included muscular hypotonia at birth and smooth velvety skin. However adding to the current knowledge, kyphoscoliosis was not necessary present at birth/diagnosis but was reported to develop later in life in some individuals. In addition, kyphoscoliosis represents a clinical feature of EDS type VIA with a high frequency of inter- and intrafamilial variability regarding severity and age of onset with no obvious association to the PLOD1 gene genotype. Age of onset of kyphoscoliosis might indirectly be of importance for progress or delay of motor developmental milestones and thus might reflect a prognostic factor for achievement of ambulation. In addition, but of utmost importance a less severe clinical phenotype seems to exist, only presenting in adulthood with acute life threatening vascular events and velvety skin, without skeletal involvement. Clinical data of additional patients is required to validate our findings and to investigate possible factors contributing to inter- and intrafamilial variability.