Introduction: Vitamin D-dependent rickets type 1A (VDDR1A) is a rare genetic disease associated with loss-of-function variations in the gene encoding the vitamin D-activating enzyme 1α-hydroxylase (CYP27B1). Phenotype-genotype correlation is unclear. Long-term outcome data are lacking. The objective of this study was to describe characteristics and outcomes to search for a phenotype-genotype correlation.
Methods: We retrospectively collected clinical data, genetic features, and outcomes from 24 genetically confirmed cases from 10 French centers; results are presented as median (min-max).
Results: Clinical symptoms at diagnosis (age, 1.5 [0.5-8.7] years) were mainly bone and neurological abnormalities, and laboratory data showed hypocalcemia (1.97 [1.40-2.40] mmol/L), hypophosphatemia (-3.4 [-13.4 to (-)0.2] SD score for age), low 25OHD and low 1,25(OH)2D3, secondary hyperparathyroidism with PTH at 6.6 (1.3-13.7) times the upper limit for normal (ULN; PTH expressed as ULN to homogenize data presentation), and increased alkaline phosphatase (1968 [521-7000] IU/L). Bone radiographs were abnormal in 83% of patients. We identified 17 variations (11 missense, 3 frameshift, 2 truncating, and 1 acceptor splice site variations) in 19 families (homozygous state in 58% [11/19]). The partial loss-of-function variation p.(Ala129Thr) was associated with a milder phenotype: older age at diagnosis, higher serum calcium (2.26 vs 1.85 mmol/L), lower PTH (4.7 vs 7.5 ULN), and lower alkaline phosphatase (759 vs 2082 IU/L). Patients were treated with alfacalcidol. Clinical (skeletal, neurological), biochemical, and radiological outcomes were satisfactory, and complications occurred if there was bad adherence.
Conclusion: Overall, our findings highlight good outcomes under substitutive treatment and the need of a closer follow-up of eyes, teeth, kidneys, and blood pressure in VDDR1A.
Vitamin D-dependent rickets type 2A (VDDR2A) is a rare cause of infantile-onset alopecia, characterized by severe hypotrichosis, small cutaneous cysts, early-onset treatment-resistant rickets, and hypocalcemia. Alopecia, often starting a few weeks to months after birth, may be the presenting feature. We present three cases of VDDR2A with genetic variants in the vitamin D receptor (VDR) gene, their clinical features and biochemical parameters.
Duan X, et al, report that CYP4A22 loss-of-function causes a new form of vitamin D-dependent rickets. Here we describe the basis for our rejection of their proposal and provide evidence that the CYP4A22 variant that they have identified (c.901del, p.
Neuronal ceroid lipofuscinosis-type 1 (NCL-1) is a neurodegenerative lysosomal storage disorder. Vitamin D-dependent rickets type 1 (VDDR-1) is a rare cause of refractory rickets. Here, we report an unusual association of NCL-1 with VDDR-1.
Vitamin D-dependent rickets type 1A (VDDR1A) is a rare genetic disorder characterized by symptoms like growth failure, rickets, and hypocalcemia, caused by mutations in a specific gene.
A study focused on two Mexican siblings with unusual symptoms including cafe au lait spots and grayish sclera, alongside typical VDDR1A features, leading to genetic testing that identified both a recurrent variant and a novel nonsense variant in the affected gene.
The findings highlight the first documented case of atypical VDDR1A in this family and suggest that certain genetic mutations may influence the severity of the condition, with the younger brother showing a better response to calcitriol treatment.
