A frameshift homozygous germline mutation in BBS7 was detected by WES and identified by Sanger sequencing in affected individuals. This mutation was predicted to result in premature termination of exon5 (c.389_390delAC, p.Asn130ThrfsX3; RefSeq NM_176824.2) and lead to a 133 amino acid truncated protein. The inheritance patterns in the families are consistent with autosomal recessive inheritance, and no such homozygous mutation was found in the other 981 controls.
Case#: Shen_2019_Patient_III-10, female, age 39 years at time of report, national origin reported as Chinese, ethnicity reported as Miao
CasePresentingHPOs: HP:0001513 (Obesity), HP:0000822 (Hypertension), HP:0000107 (Renal cyst), HP:0010442 (Polydactyly), HP:0000750 (Delayed speech and language development), HP:0000678 (Dental crowding), HP:0011342 (Mild global developmental delay), HP:0001156 (Brachydactyly), HP:0000470 (Short neck), HP:0005280 (Depressed nasal bridge), HP:0000140 (Abnormality of the menstrual cycle)
CaseHPOFreeText: The patient has been diagnosed with Bardet-Biedl syndrome.
CaseNotHPOs: HP:0000134 (Female hypogonadism), HP:0002194 (Delayed gross motor development), HP:0000708 (Atypical behavior), HP:0000819 (Diabetes mellitus), HP:0000365 (Hearing impairment), HP:0000518 (Cataract), HP:0000639 (Nystagmus)
CaseNotHPOFreeText: N/A
CasePreviousTesting: Previous genotyping consisted of exome sequencing.
CaseMethod1: exome sequencing
CaseMethod2: Sanger sequencing of the BBS7 locus
CaseGenotypingMethod: Genotyping consisted of exome sequencing, followed by Sanger sequencing of the BBS7 locus.
Variant: The patient harbors the NM_176824.3(BBS7):c.389_390del (p.Asn130fs) variant in the homozygous state.
ClinVar ID: 216138
gnomAD: The NM_176824.3(BBS7):c.389_390del (p.Asn130fs) variant was not found in gnomAD v2.1.1.
VariantEvidence: NM_176824.3(BBS7):c.389_390del (p.Asn130fs) is an out-of-frame deletion variant in exon 5 of 18 that is predicted to trigger nonsense-mediated decay or at least truncation of the C-terminal 82% of the protein product.
CaseAddInfo: Consanguinity in the proband's family is suspected but has not been confirmed. She has two similarly affected cousins who share the same homozygous genotype. The carrier status of her unaffected parents and an unaffected sibling have been confirmed by genotyping.
CasePMIDs: N/A