A rare case of Waardenburg syndrome with unilateral hearing loss caused by nonsense variant c.772C>T (p.Arg259*) in the MITF gene in Yakut patient from the Eastern Siberia (Sakha Republic, Russia)

Figures & data

Figure 1. The case of the WS type 2 with variant c.772C>T (p.Arg259*) in the MITF gene

(a) pedigree of Yakut family with WS type 2. Arrow points on proband (II:4). Filled symbols represent family members with hearing loss: bilateral hearing loss is shown in black, unilateral hearing loss – in grey. (b) Proband II:4: unilateral iris heterochromia (right eye is dark brown, left – diamond blue with some brown pigmentation). Dystopia canthorum index (W) was calculated according to [2] – W = X + Y + a/b; where X = (2a-0,2119c-3,909)/c, Y = (2a-0,249b-3,909)/b; a – the distance between the inner corners of the eyes (mm), b – the distance between the pupils (mm), c – the distance between the outer corners of the eyes (mm). Index W for proband II:4 was calculated as 1.66 (0.47 + 0.69 + 32/64) that indicates the absence of dystopia canthorum (<1.95 cm). (c) Audiograms of proband in range from 0.25 to 8 kHz, AD – on the right, AS – on the left. (d) Partial sequence chromatogram of MITF fragment (exon 8): upper panel – arrow shows the location of heterozygous variant c.772C>T (p.Arg259*) detected in proband II:4, lower panel – normal MITF sequence (Reference sequence: NM_000248.3).

Table 1. Phenotype of observed patient with Waardenburg syndrome

Phenotypic features	Proband II:4
Gender	Male
Age	17 years old
Ethnicity	Yakut
Type of inheritance	AD
Hearing loss	Unilateral
Degree of hearing loss	Profound on the left (>90 dB in speech range), normal hearing on the right
Communication	Speech/Sign language
Eyes	Unilateral iris heterochromia (right eye is dark brown, left – diamond blue with some brown pigmentation
Skin	Normal pigmentation
Hair	Normal pigmentation
W index	1.66 cm
WS type	2

Age is stated as on the moment of examination (May 2015); speech range (0.5, 1.0, 2.0, 4.0 kHz); dB – decibels; AD – autosomal dominant; W index – dystopia canthorum index: value over 1.95 cm signs on presence of dystopia canthorum; WS type – Waardenburg syndrome type.

Reed WB, Stone VM, Boder E, et al. Pigmentary disorders in association with congenital deafness. Arch Dermatol. 1967;95:176–186.

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