Copy number variants that duplicate distal upstream enhancer elements of the SOX9 gene cause 46,XX testicular differences of sex development (DSD) which is characterized by a 46,XX karyotype in an ...individual presenting with either ambiguous genitalia or genitalia with varying degrees of virilization, including those resembling typical male genitalia. Reported duplications in this region range in size from 24 to 780 kilobases (kb). Here we report a family with two affected individuals, the proband and his maternal uncle, harboring a 3.7 kb duplication of a SOX9 enhancer identified by clinical genome sequencing. Prior fluorescence in situ hybridization (FISH) for SRY and a multi-gene panel for ambiguous genitalia were non-diagnostic. The unaffected mother also carries this duplication, consistent with previously described incomplete penetrance. To our knowledge, this is the smallest duplication identified to-date, most of which resides in a 5.2 kb region that has been previously shown to possess enhancer activity that promotes the expression of SOX9. The duplication was confirmed by quantitative-PCR and shown to be in tandem by bidirectional Sanger sequencing breakpoint analysis. This finding highlights the importance of non-coding variant interrogation in suspected genetic disorders.
The Inborn Errors of Metabolism Collaborative (IBEMC) includes clinicians from 29 institutions collecting data to enhance understanding of metabolic conditions diagnosable by newborn screening. Data ...collected includes hospitalizations, test results, services, and long-term outcomes. Through evaluation of this data, we sought to determine how frequently genetic counseling had been provided, how often genetic testing was performed, and also determine the consanguinity rate in this population. A data query was performed with the following elements abstracted/analyzed: current age, metabolic condition, whether genetic counseling was provided (and by whom), whether genetic testing was performed, and consanguinity. Genetic counseling was provided to families 95.8% of the time and in 68.6% of cases by a genetic counselor. Genetic testing was performed on 68.0% of subjects, with usage highest for fatty-acid-oxidation disorders (85.1%). The rate of consanguinity was 2.38%. Within this large national collaborative there is a high frequency of genetic counseling, though in one-third of cases a genetic counselor has not been involved. Additionally, while metabolic conditions have historically been diagnosed biochemically, there is currently high utilization of molecular testing suggesting DNA testing is being incorporated into diagnostic assessments - especially for fatty-acid-oxidation disorders where the underlying genotype helps predict clinical presentation.
Keppen-Lubinsky syndrome (KPLBS) is a rare disease mainly characterized by severe developmental delay and intellectual disability, microcephaly, large prominent eyes, a narrow nasal bridge, a tented ...upper lip, a high palate, an open mouth, tightly adherent skin, an aged appearance, and severe generalized lipodystrophy. We sequenced the exomes of three unrelated individuals affected by KPLBS and found de novo heterozygous mutations in KCNJ6 (GIRK2), which encodes an inwardly rectifying potassium channel and maps to the Down syndrome critical region between DIRK1A and DSCR4. In particular, two individuals shared an in-frame heterozygous deletion of three nucleotides (c.455_457del) leading to the loss of one amino acid (p.Thr152del). The third individual was heterozygous for a missense mutation (c.460G>A) which introduces an amino acid change from glycine to serine (p.Gly154Ser). In agreement with animal models, the present data suggest that these mutations severely impair the correct functioning of this potassium channel. Overall, these results establish KPLBS as a channelopathy and suggest that KCNJ6 (GIRK2) could also be a candidate gene for other lipodystrophies. We hope that these results will prompt investigations in this unexplored class of inwardly rectifying K+ channels.
Adults with PKU have difficulty maintaining plasma phenylalanine (Phe) in the range that is safe for neurologic function. Elevated plasma Phe is a risk factor for congenital anomalies and ...developmental delay in offspring resulting from pregnancies with poor Phe control in women with PKU. Enzyme supplementation with pegvaliase allows adults with PKU to eat an unrestricted diet and have plasma Phe levels in a safe range for pregnancy but pegvaliase has not been approved for use in pregnant females with PKU. We report the results of chart review of 14 living offspring of females affected with PKU who were responsive to pegvaliase and chose to remain on pegvaliase throughout their pregnancy.
Fourteen pregnancies (one triplet pregnancy) and their offspring were identified at eight PKU treatment centers and medical records from pregnancy and birth were submitted for this study. Institutional Review Board approval was obtained. Responses to a dataset were provided to a single center and analyzed.
Six females and eight males were born without congenital anomalies and all offspring had normal growth parameters. While mothers had preexisting comorbidities, no additional comorbidities were reported in the offspring. Four of eleven infants (excluding triplet pregnancies) were delivered preterm (36%), a higher rate than the general population (12%). A single first trimester (eight weeks) miscarriage in a 40y was not counted in this cohort of 14 live born infants. CONCLUSION: This retrospective study suggests that pegvaliase is effective at maintaining safe maternal blood Phe levels during pregnancy without deleterious effects on mother or child. A tendency toward premature birth (4/11; 36%) is higher than expected.
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